First posted 6/2005 R. Kwas, additions on-going,  Comments added in Yellow.

Information for the well informed installer of the SW-EM Alternator Upgrade Kit

Included are also some practical experiences and feedbacks by installers.   


Generator and Alternator Mounting Provisions on B18 and B20s
Special Applications
$40 Alternator Experience
Failure of (modified) Alternator Housing
...just install a "One-Wire Alternator"!
Minor Installation Error
Installing a 100A Alternator
Another $40 Alternator Experience 
Alternator Thermal Considerations

Alternator "R" Terminal
Delco Alt on OE Cast Bosch Pivot
One spacer washer fits between Alt Pivot Boss and Bracket, two don't 
Broken OE Alternator Pivot Bolt
Locking the Alternator Pivot
Failed Non-SW-EM Alternator Bracket
Alt Kit Bracket Interference with FI Manifold Support Arm (and remedy)
Result of loose Alternator
Loose Fanbelt Tensioning Bar Threads in Cylinder Head
Alternator Output Rating Discussion (reposted from FB)  
Squealing Fanbelt
Remote Voltage Sensing Installation Variation
Alt Kit not as shown in Alt Kit Description Page
Stealth Alternator Installation!

Turnbuckle Fanbelt Tensioner

Links not on this page:
Alt Kit Pivot bolt with a "Drunken Thread"!
Failed SW-EM Alternator Kits
Alternator Installation Failure Report and Analysis


Generator and Alternator Mounting Provisions on B18 and B20s
All B18 blocks had the three holes (Yellow) for securing Generator Bracket. 
Late B18s and all B20s added the (Green) Pivot for OE (Bosch and Motorola) Alternators.  This OE pivot is NOT suitable for mounting a Delco Alternator because of differences in the Alternator cases (see also Special Applications below). 

Picture of a B20 with both pivot and bracket holes. 

See also:  Broken OE Alternator Pivot Bolt


Special Applications

Mounting an o.e. Bosch alternator using the SwEm Kit bracket.  This situation has occurred twice - first, when the threaded mounting boss of a B20 block broke off (?), the bracket saved the day because it is secured to the block by the three threaded holes which were used on B18 block castings to mount the generator bracket, and fortunately were retained on B20 castings (although unused); and second , when a new Bosch alternator and (mechanical) regulator were already on hand, and didn't need to be purchased.  Since no mods to bracket were necessary in this case, the option still remains for a future upgrade to a higher output D-R alt. with internal solid state regulator.

The following mechanical differences between D-R and Bosch alternators exist:

1.  The Mounting boss nominal length of the alt. castings.  Bosch is shorter.  See Pictures 1 and 2.  Solution:  Use a spacer (or a stack of washers), sized to take up remaining space, but this spacer must be sized after cutting (Bosch) casting to correct for belt plane offset - See highlight on pic No.1 - once bolt is torqued, everything is locked from movement.
2.  The Pivot bolt sizes.  Bosch used a larger bolt than upgrade kit, so pivot hole in casting is larger.  When using smaller bolt from upgrade kit, this could cause misalignment.  See Picture 3.  Solution:  Use metal tubing or strategically sized and formed piece of sheetmetal to center pivot bolt in larger hole of Bosch alt., again, once bolt is torqued, everything is locked from movement.

3.  Belt Plane.  Different offset of alt cases.  Solution:  To make offset equal to that of D-R alt., and assure pulley alignment, cut away 3/8" of casting as highlighted in Picture 1.

Picture 1, Delco-Remy Alt. on left, Bosch on right.  Offset in mounting boss of Bosch casting which causes pulley misalignment is highlighted.

Picture 2,  Showing mounting differences from another angle (Bosch alt. on top).   Pivot boss length differences are visible.

Picture 3,  Showing mounting differences in castings and pivot bolt holes.


$40 Alternator Experience

posted by timbert on Wed, Dec 11th 2002 at 7:47 PM

I switched over to an alternator on my '66 122 - using the fabulous SWEM kit - several months ago.  [WOW...Thanks!]  The one piece of advise that I didn't heed was to not buy the cheapest AC Delco type alternator I could find ... I bought one for $45 at the local auto parts super store. Everything seem to work okay for a couple months. For a while now, the alternator has been making quite a racket & the alternator pulley/fan looks to be wobbly - but everything seemed to still work & it has been awfully cold & wet & dark to be swapping out the alternator, so I just let it slide.

Today, when driving home at night - in a cold rain with wipers & fan going, the headlights seemed quite dim & then, when I switched into overdrive, the radio cut out momentarily. The amp light, however, never came on.

As I understand it, the amp light will light up if there is a difference between the voltage produced by the alternator and the voltage of the battery charge. So, my WAG (Wild Ass Guess) is that the alternator is not producing enough amperage which caused the problems I experienced tonight.

Am I understanding the situation somewhat correctly? Are excessive noise & low output consistent symptoms of a faulty alternator ?

I realize that this is probably overly simple question, but I am trying to learn as best I can how to keep this thing going.

thanks for the continuing education


posted by
Ron Kwas on Thu, Dec 12th 2002 at 8:26 AM (amended and corrected)


That is totally typical of the $40 "rebuilt specials". If the alt was making serious mechanical noises that soon, it probably means that it didn't get new bearings when they "rebuilt" it...I wonder what else it didn't get...that's why I recommend paying for and installing the official AC Delco rebuilt ones...but it's your call of course.

As to the symptoms, dim lights indicate the alt is probably not putting out (loose belts and/or wires or that sort of thing notwithstanding), and the fact that the AMP light did not come on is somewhat unusual, but not impossible. There are some failure modes which do not result in AMP Indicator coming on...especially if you installed a "unknown" alt.

In the OE gen setup the AMP lite is connected as you state...but after the upgrade it is slightly different...then the AMP lite supplies the field power to start the alt generating power...after that, it "self-excites", so it could be putting out enough voltage to keep the AMP lite OFF, put NOT really putting out power.

Have you performed the "full field test" as described in the instruction? This bypasses the regulator and applies full field...if it doesn't put out then (indicated by system voltage rise - connect Voltmeter to monitor system voltage) that confirms alt is for s**t (which we kinda knew already anyway).

...bottom line is:  Remove alt, take to a competent automotive electrical place, have them check electrically, replace BOTH bearings and other words: Really Rebuild! OR, check paperwork I sent you with kit and buy the recommended alt.

Live and me now or pay me later...I told you so...close cover before striking... etc...etc...etc


... thanks for the kind words!

See also:  Another $40 Alternator Experience below.


 Failure of (modified) Alternator Housing                                                                                                              added 7/2010 

A simple solution is often the best solution, and simple should always be the goal, but beware of oversimplification!  Often, cutting away of part of the housing pivot is recommended as a simple way to allow an alternator to be used with the existing generator bracket.  Maybe some owners have had success with this, and their installation hasn’t failed (yet), but the fact is that removing part of the structure of the alt pivot is BAAAAD, it weakens the housing and cuts into the structural safety margin of the entire mounting system…if this is further combined with a mounting which allows any kind of movement or vibration, you can be fairly certain that the combination will let you down at some point!...and having cut the housing to fit it, surely killed any warrantee which you might need to exercise in the future.  Think twice before going the Quick & Dirty and oversimplified route…that’s really not why we drive these cars!

Shown below is a classic example of a failed Quick & Dirty alternator conversion…the (not so) clever installer simply cut away half of the pivot unceremoniously with what looks like a hacksaw, leaving a horrendous stress riser visible in the pic, (although it is also apparent that the stress riser did not cause this particular case), then used a bolt (which was likely too small in outer diameter), threaded along its entire length, including the part of the bolt which was in the pivot area.  This contributed to allowing vibration which shouldn’t have occurred in the first place, to cut remnants of these threads into the pivot inner wall, before eventually leading to the fracture which broke away what was left of it.  I wonder just how long (or short) of a time this installation lasted before it blew apart. 

The installer who did this work should consider switching careers to one which involves a shovel

WARNING:  Picture of a major hack-job, looking at which may induce vomiting, follows:

FIGURE 4.  Alternator housing, fractured at pivot which has been partially cut away. 
Also visible is evidence of vibration.  Picture credits:  Woodman

I warned you!  


The custom designed and fabricated bracket which the SW-EM Alt Kit is based on, will allow the installation of an unmodified Delco alt with a housing unweakened by cutting.  This means that the alternator housing retains its full strength, as designed, and it remains unmolested, giving the maximum strength to the mounting system, and putting the owner in a solid position for any possible future warrantee claims. 

LINK to “bad workmanship” thread on British Forum


Another Alternator victim of butchery...or "you can just cut half the Alt case away and bolt it to the'll be fine", and what happened a while later. 

Don't do it!  Just remember...the friend or "specialist" who gave that advice will not be there to help, or take responsibility, for any of the damage, when it finally flies apart! 

"One-Wire" Alt (evidenced by the plastic plug at Orange covering the Input Connector) with fractured (actually worn-through) case.  In the poorly lit picture, it is still possible to make out the pivot which has been once again, partially cut away at Red, and in doing so, much of the bearing area for the mount has been lost, so as the Alt vibrated (a secondary issue due to poor mounting!) it eventually wore its way through the side of what was left of the pivot.  The "mechanic" who did this conversion should probably consider changing careers to one which involves a shovel!



"...just install a 'One-Wire' Alternator"!

[ I just had to reprint this answer to an e-mail question I received.]

A recommendation of "just install a 'one-wire' alternator" or similar is someone's quick, off the cuff, unconsidered, and incomplete advice, typically given to make the installation seem as simple as possible...

I can totally understand the appeal of this...I mean its pretty tough to screw up connecting just ONE lonely wire (not that it couldn't be done!)...but I have considered the details:  The AMP Indicator cannot function with a one-wire installation...and there are Alt. housing variations which must be considered given the wiring and alt location right next to the exhaust in the B18/20 kit has been engineered taking all these factors (and then some!), into careful consideration...and it is backed by literally thousands of successful if you're capable of following the explicit instructions included in the kit, and buy one of the specifically recommended, official, quality, Delco rebuilt Alts, and are capable of connecting THREE wires to the Alt., you will end up with a charging system in your vintage Volvo which has lots of electrical and mechanical operating margin, and which is therefore highly reliable...and also, an AMP Indicator which still functions, just like before! 

See more here: Explanation of "One-Wire"

--------------- --------------------------------------------------------

Minor Installation Error:  Occasionally, like when an engine is apart for a while for a rebuild, someone might forget where things go when they put it back together, and get it this installer, who located the engine end of the Belt tensioning bar in the wrong (Red) upper hole in the head...we won't hold it against this installer (let those without sin cast the first stone!)...apparently he quickly realized the error and corrected it, by relocating the Bar securing point in the correct (Green) hole, but I thought it would be interesting to show here...  Funny thing is that the adjustment slot was even long enough to allow the incorrect placement. 

Belt tensioning Bar located in the incorrect upper hole (Red) in head, when it should be located, as before, in lower (Green) hole. 
Also visible is the pivot cast and machined into block for OE Alternators (Yellow) and new pivot (Orange) provided by SW-EM Kit bracket.

Correctly mounted Delco Alternator, including Belt Tensioning Bar...
Beautiful, and ready to render reliable service for a long time!


Excerpt from an e-mail asking about Installing a 100A Alternator:

I recommend not going above ~60A output, even with AC installed.  Track record with ~60A Alts has shown continued very good reliability (zero recorded failures as a function of output current!).  If you insist on putting in a higher power unit instead of one of the ones I recommend, you do this on your own...and YOU are then responsible for the engineering!   The Bracket will certainly take it, but you WILL need to uprate wiring, and definitely Fuseblock...and don't come back complaining to me when your [formed sheetmetal!] Water pump pulley fatigues (from the additional possible cyclic load), blows apart, and possibly launches the Fan into the Radiator! [...because the Fanbelt had to be over-tightened to keep from squealing like a pig when it is transferring all the mechanical energy to make 100A!]  I don't want to be a naysayer, but remember, when strengthening the weakest link in a chain, the next weaker link will be exposed and vulnerable...!

Fatigued WaPu Pulley, possible the result of over-tightening Fanbelt,
but there is a good chance of this happening with a 100A Alt installed! 

See also:  Alternator Output Rating Discussion (reposted from FB)


Another $40 Alternator Experience:

My response to Andrew C 9/11/2016:  Shredding Belts on an Alt installation: 

The alternator is working fine electrically, but it is shredding belts. I have tried 3 so far, and have been very careful to tension them, the first 2 squealed horribly then snapped, the last one just gave up and dropped off somewhere, and the AMP light came on.

The angle of dangle of the pulleys relative to one another seems ok. The pinch bolt is nice and tight, tension seemed OK and the pivot was cinched up too.

What am I doing wrong? What would cause this?  My Response in Blue:  As a rule, Belt should be in a single plane, which obviously means pulleys must also be (it should be noted that Belts can take a LOT of misalignment [they are fiber reinforced, but after all, still a flexible rubber band!]...recall the 90degree turn with 90 degree axial twist of the 60s Corvair installation!), but I suggest you check this critically with a fresh eye again!...triple holes into block for Alt bracket are slightly oversized to allow some minor adjustment... but this is first time I've heard of multiple belts shredding themselves, so something is very wrong indeed!  It may be an possible misalignment of pulleys (although I fail to see how, unless something is assembled wrong, but I can't imagine what might be either!), or that one of the driven pulleys (WaPu, Alt) are sluggish to turn somehow (remove belt, check bearings in each for free turning ability) and at the same time, I'd also check all pulleys for imperfections on the belt running surface which might be damaging the belt (although minor ones of these would normally get polished away after a short while of running), but maybe a significant nick in pulley is insulting the belt every time it touches it, taking a chunk out of it, leading eventually to belt failure.  More likely, a squealing belt is caused by a very high (maximum) electrical load causing belt to slip...if allowed to persist, this will overheat belt and can lead to failure, as it has in your case (multiple times!)...what is State of Charge of Bat? ...have you charged Battery overnight with a line powered Charger? should!...expecting Alt to recharge a completely flat Battery (or a Battery with a shorted cell, which will continuously load the hell out of Alt) will result in a persistent high-Alt load condition which won't be doing the belt any favors, and can lead to these symptoms.  Also, CAREFULLY feel around (or look with an IR temp scanner) for hot spots in the elec system...all that elec energy generated under max load condition would be going somewhere!  That's all I can think of right now...  Again, if you wish to discuss live, you're welcome to call me today at XXXXXXXXX

I am going to take the alternator off tomorrow as it will aid me in removing the manifold, I will have another closer look at the bracket and see if the pivot needs packing or something.  Take and fwd a picture just off the plane of the belt to allow me a look, before removing.  I'd be quite interested in knowing and understanding root cause of this issue, as it is rare and preventative measures might need to be included on SW-EM site, or at least in Alt instruction.  Good Hunting!

The exact cause for the shredded Fanbelts was not initially fed back by this it was, he returned the Alternator to the supplier who replaced it with another...when he installed the replacement, the problem was cured!  It should be noted that this WAS NOT an official Delco rebuilt unit, but one of the second source suppliers, proving once again that you usually get what you pay for!

Update:  This is the feedback from this installer:  "Yes, I did have shredded fan belts. The reason was a “knackered” alternator, i.e. it was almost seized.  It was a very cheap rebuilt one, I should have known better.

Anyway, I got a nice AC Delco one and it has been fine ever since. It was nothing to do with your alternator mount. "  All's well that ends well!



Alternator Thermal Considerations: 


Cooling air is drawn into the rear of Alt, past the electronic components, and is discharged out the front,
by way of the centrifugal impeller.  Green (A) is a threaded hole in Alt Housing.  It can be used to connect an addition Chassis Cable, and possibly to secure a Heat-Shield (see below).  Note the direction of rotation (yellow). 

I haven't had any reports of heat-damage to an Alt upgrade [MAR 2022 Correction:  Limited! update in in the works on this!], so I don't think a Heat-Shield is necessary, but given the above, my recommendation for anyone considering adding such a shield would be to form it as shown here in yellow:

Heat-shield concept for Delco Alt installation:  Heat-shield (Yellow) would block warmer air plus radiation from Headpipe from rear of Alt while directing cooler air (Blue) from the front of Alt into the Cooling Air Intakes.  It could (and must be!) WELL secured by single fastener into threaded hole in Alt case (Green A).  It would be highly advisable to also use two additional securing points (Green B) at the Alt housing bolts). 

Note:  All advantages would be quickly negated if your groovy Heat-shield were to loosen and short the Alt output stud to chassis!

Link to Brickboard Thread:  Alternator Heat Shield:

While on the subject of Heat Shield and Cooling Air flow, here is a reference picture of a Delco Alt installation with an IPD header.  The hot exhaust is not too far away, but there's plenty of Cooling Air available given the general direction of the airstream and the hurricane of turbulent airflow occurring under the hood!   



Alternator "R" Terminal:

From FB thread about installing a Tach originally for a diesel powered vehicle with a W terminal on Alt ("R" terminal on Delco Alts):  

I agree that a Tach originally meant for a diesel (which has no Ignition System from which to take an RPM related signal) cannot be directly used to monitor RPMs on a gasoline powered engine, but understanding how it does work on the diesel, and a bit of engineering, allows using it on a B18/20! 

Calibration:  The only question in operating a former Diesel Tach in a different Alt would be the relationship of the frequency at the W ("R") terminal at a given RPM, on the original engine, versus the frequency from another Alt, and this would clearly be a function of the pulley diameter of the original Alt which the Tach played with vs. pulley Dia of the Delco.   

From those Links:


...and if the Alt does not have a W terminal (R for Relay on Delcos [don't ask me why!] cast into Housing), it can simply be added to one of the output phases as seen above!  Note that the "Bat" terminal (2) should more correctly be named:  Sense, to avoid confusion with Battery (output) terminal. 

Taking the Tach signal from the Alt also reminds one of early mechanical Tach drives, which would be taken by a speedometer-like cable drive from the Generator. 

Reference Link to thesamba thread:  European alternator “W” wire question 1.9 AAZ


Alt Kit Pivot bolt with a "Drunken Thread"!

Discussion on Swedespeed Forum:  "New 1800E owner, longtime Volvo owner - question about alternator options"


Thread about installing a SW-EM Alt Kit:

My posting to that thread


I realize this is an ancient thread, but I ran across it again while doing some research and wanted to chime in with a couple of stupid comments. First, a big THANKS all who recommended the engineered Sw-Em alt kit!

Advice often seen: "simply install a "One-Wire" Alternator..." that's oversimplified advice (it comes from people working on tractors, who apparently have trouble when working with more than ONE wire!), given by those who want to make it sound as easy as possible...what they don't mention is that when doing that, you also loose AMP Indicator function! If you can handle following specific detailed instructions, and connecting up all of THREE whole wires without screwing it up, that's the preferred way...and you'll retain the function of the AMP Indicator...just like before!

A couple of words about installing a 100A Alternator: First, a question: What would you possibly need that much power for in your car? Add up all the Loads (including the intermittent/occasional ones like Window lifts and Rear Window Defroggers) and you'd probably have trouble exceeding 1200W. And if you have a 1000W stereo installed, know that it draws less than 1/10 of that when turned up to make your ears bleed!...the only times it truly draws 1000W is on bass peaks, and they don't last very long (unless your showing off, in which case I probably can't help you!). If you want to supply bass peaks for a killer stereo, install some soup-can capacitors, and be done with it!

Also, those 100A don't come from nowhere!...they come from the engine...more specifically, the Crankshaft, by way of the Crankpulley, Fanbelt and (sheetmetal) [B]Water Pump Pulley[/B]...if you install a 100A Alt, in order to transfer that much mechanical energy through one belt (without squealing like a pig, if it's possible at all), you'll have to tighten up the Belt like that of a high-wire act across Niagara Falls...then you may get this for free: good luck!

...and I haven't even mentioned the wiring yet...remember...when strengthening one part, the next weakest link in the chain will be the one to break! If you simply want a reliable electrical system in your vintage Volvo, vigorous Wipers, WHITE Headlights, and a fully charged Battery with which to get started next time, I recommend and have engineered the kit to install a 60A Alt...then drive it like you hate it, knowing that it will likely be as reliable as thousands of customer miles have shown!



Delco Alt on OE Cast Bosch Pivot: 

Alt kit inquiry from Matt Y.:  (Comments added)

"... the (Delco) alternator that is currently installed on my 122 is using the cast mounting point (I call it the OE Pivot) on the B18 block.  It is out of alignment by 7-10mm, the alternator bracket is at the end of its reach and interfering with the alternator body so I can’t get the belt any tighter (it squeals on start up).  I’m curious if moving to one of your brackets would solve this for me and give me the clearance I need to get on a smaller belt?  The alternator is limited by the coolant hose when moved inwards. I’ve attached a couple of pics for reference." 

Matt's pictures used with his permission.  


Excerpt from my response "...the pictures...they show the misalignment (high, close to exhaust, and toward the rear, as apparent above in comparison of Alt housings), well, (at least installer didn't cut away part of the Alt housing to make it fit, see: Failure of Modified Alt Housing ) and yes the SW-EM Kit would absolutely cure all the issues (Alt position, therefore belt misalignment, adjustment range, interference) because it will relocate the alt a bit lower (as can be seen here:  SW-EM Alternator mounting provisions B18 and B20  )


One Spacer Washer fits between Alt Pivot Boss and Bracket, two don't: 

...from and Alt Kit Washer spacer issue email exchange...: 

From A.D.:  The alternator is loose within the bracket, but there is not enough space for two washers, so I can think of filing the mounting boss to allow for another washer or dismount the bracket and close it a bit, the play between the bracket and the alternator boss is less than 1 mm, but is enough to have it wiggle when the pivot bolt is fully tightened.

Response:  There is typically only room for installing one washer on a nominally sized [2 inch] alternator pivot boss, so its not a problem if there is not enough room for two washers. The remaining gap will be closed when tightening the pivot bolt. The intent of installing a washer is to take up excessive gap.

A.D.:  Unfortunately, the gap does not close after tightening, I guess that the remedy left is to put two washers, which will require a bit of filing on the alternator boss.  I have been following the Tech bulletin to the letter.

Response:  Again, the washer(s) are only present to take up excessive space...that's it!...if one washer fits, but not two, you could simply pry apart the bracket slightly (if possible...I realize the bracket is quite beefy and may not allow this)...or as you suggest, file the mounting boss slightly to make room for the second washer, or even cut another thinner spacer washer, or two, from a thin piece of sheetmetal (like even a soda can) and use that...I realize that coming from the aerospace world, you have been trained to follow instructions to the letter (and that is certainly good!!), as instructions have been authored by highly qualified individuals after much consideration (as have mine!), but in this instance, it's just not critical, and you may make a "judgement call" (you may not have an Airframe and Powerplant (A&P) rating, but in this case, its allowed!)...the important thing in the end when all hardware is fastened to final torque, that Alt is ONE with bracket, and bracket is ONE with engine, in both cases meaning that NO relative motion is possible.  [See below!]  

A.D.:  I filed a bit the alternator boss, added one washer and problem solved. 

Response:  Great! 


Mechanical conditions between Alternator Pivot Boss and SW-EM Bracket. 


Broken OE Alternator Pivot Bolt:  [This is not a failure of the SW-EM conversion, but of the OE arrangement with Bosch Alt, and demonstrates once again how important proper mounting of an(y) Alt is.]

A failed OE Bosch Alt mounting occurred, due to looseness of pivot bolt allowing vibration and failure of the (1/2"!!) pivot bolt.

[As I have noted before, the OE design is an "Overhanging Load" (or "Cantilevered Mass" ), as mass of the OE Alt is supported ONLY on one side of the Alt housing pivot.  This is quite OK when everything is nominal and tight and no movement is possible.  If however the pivot bolt were to loosen for any reason (or not be properly tight in the first place), the system and mount would be subjected to horrendous forces generated in the overhanging mass mode, on mount and pivot bolt, the vibration input, and plenty of it(!), being transferred by the Fanbelt, and in this case sufficient to eventually fatigue and break the beefy 1/2" pivot bolt!! 

Alternately, I have also heard of the mount on the engine block also break off (no picture, sorry)!!  This is much less so the case in designs where support is provided on BOTH sides of the pivot, as with the SW-EM design bracket. A double sided support design is therefore somewhat less susceptible to catastrophic failure, AND also much more failure-tolerant if one were to occur!]

Where loose Delco Alts have caused failures, this shows that a loose OE Bosch can suffer under the same situation! 

Failed OE Bosch Alt mounting due to looseness of pivot bolt allowing vibration and failure of (1/2"!!) pivot bolt.  Note Galling, a sure indication that Alt was vibrating and not securely fastened!

Aftermath of a loose Bosch Alternator!  Even a 1/2" Bolt is no match for cyclic fatigue!
Picture by Vaughn H. and used with his kind permission. 

Link to Thread!&p=7293589#post7293589 

In the picture, circumferential galling is the unmistakable evidence of long-term vibration between two surfaces, and scarring at 4-7 O'Clock likely occurred just after final separation, when jagged edges of bolt vibrated against pivot. 

My comments to thread: 

"Such a failure is a rare occurrence, but not one which hasn't happened before...and galling apparent on the pivot from 1-4 O'Clock is clear evidence that pivot bolt or Fanbelt tensioning bar, or both were loose, allowing movement of the Alt, causing cyclic forces on bolt which caused breakage...there is certainly plenty of vibration input from the belt! Alternator should be checked to be absolutely secured to block and not being able to move in any axis...good practice is to check for secureness of Alt (and tightness of Fanbelt) any time hood is opened for fluid checking or other service.  I would wager that the

On the Alt conversion brackets which I offer, the ONLY failures which have occurred on Alt housing, or bracket or pivot bolt, have occurred for the same reason: Looseness, and the fact that there was relative movement between Alt case and bracket, or bracket and block!  If Pivot bolt is properly torqued, after the Fanbelt has been tensioned, Alt will be securely ONE with block, and will stay that way!...but I include a nylock jamnut in my kit for additionally locking the pivot bolt in place (belt and suspenders...a triple safety feature, just because I can!). "

[I would bet a Hot Fudge Sundae that such a failure was caused by the pivot bolt not being tightened, AFTER fanbelt tensioning!]  


Locking the Alternator Pivot: 

...not to make a big deal of it, but it must be pointed out that installers have gotten it wrong, by not doing the last step (3), which resulted in mechanical failures!  The Pivot must be locked after Fanbelt tensioning!

The proper technique and procedure for securing the Alt in the SW-EM conversion, is to FIRST tension Fanbelt, then, lock the Alt from pivoting (and vibrating!) by securing Pivot Bolt to final Torque. The Torque required can, and should simply be checked before BEFORE tensioning Fanbelt, by tightening Pivot Bolt until it locks Alt from pivoting...and it should be able to lock the Alt in-place by approx 30-35Ft/Lbs, certainly needing no more than 40Ft/Lbs! 

A Torque Gauge is not absolutely necessary for this, but if the Torque required to lock Alt from pivoting seems extraordinarily high, the situation of an undersized Alt Pivot and excessive play between Alt Pivot and Bracket Wings may be occurring, so the Spacing Washer supplied with the kit may be necessary to close the gap (see:  ...Spacer Washer above!).

CRITICAL TIP to Installers:  Installer is NOT done when the Fanbelt Tension has been set, and its securing Bolt tightened!  The Alt Pivot Bolt MUST be torqued and Alt Locked in Place after that also!  


1.  Preperation:  Test tighten Pivot Bolt to assure it will lock Alt from pivoting (if necessary, install spacer Washers supplied with Kit!).  Loosen Pivot Bolt again, to allow Alt to pivot, in preparation for Step 2.

2.  Tighten Fanbelt by pivoting Alt Housing.  A lever between Engine and Alt can help.  Tighten Bolt which secures Fanbelt Tensioning Bar to Threaded Adjustment Lug of Alt Housing.  Do not overtension Fanbelt! 

3.  Lock the Alt from pivoting (or vibrating in service!) in Bracket Pivot by tightening Socket Head Pivot Bolt.  Use 5/16" Hex Wrench.  I installer is not certain Alt is locked from pivoting, simply loosen the bolt securing the Fanbelt Tensioning Bar in Step 2...Alt should not pivot, loosening the Fanbelt...if it does, pivot was not adequately fastened!  Go back to Step 1!  If Alt does not pivot when loosening bolt securing the Fanbelt Tensioning Bar, pivot Bolt is adequately tight to lock Alt in place, and bolt securing the Fanbelt Tensioning Bar can be retightened, and installation can proceed to Step 4.

4.  Finally, Tighten the (optional) Secondary Locking Jamnut (Nylock) to lock the Pivot Bolt in place. 



Failed Non-SW-EM Alternator Bracket: 

Occasionally, someone will make their own bracket to fit a Delco Alt onto a B18/20 engine.  The one below actually looks decent, but without the lower hole on the base, supporting the structure against torquing from Belt tension variations with vibration, and from the unmistakable evidence of galling left at the pivot holes, it clear that the Alt was doing a little dance (NO, a lot of dancing!) which finally lead to a fatigue failure of both pivot tabs.  Allowing MOVEMENT of the Alt is what causes things to fatigue and break!  This broken non-SW-EM bracket has now been replaced by an official SW-EM bracket with that third hole for stability! 

Austen B. picture, used with his kind permission.


Alt Kit Bracket Interference with FI Manifold Support Arm.  

When installing the SW-EM Alt Kit on FI vehicles, it has been observed that the Support Arm for the Intake Manifold will interfere slightly with rear of alternator bracket.  D. Waterman remedied this by trimming 5/16" from the left side of bracket as shown below.  This adjustment results in clearance to the Support Arm, and allows the bracket to mount in place normally and without further problems.  This modification of bracket does not affect the overall mounting system or strength.  David Waterman pictures used with his kind permission. 

SW-EM alternator bracket on a fuel injected engine.  Interference with Manifold Support Arm is apparent at BLUE.

Detail of SW-EM alternator bracket area which needs to be trimmed/removed when installing on an FI equipped engine. 


Result of loose Alternator (mounted on SW Alt Kit bracket):

There is plenty of Vibration being transferred to the Alt by the Fanbelt any time engine is running.  The Alt must be absolutely solidly mounted to not be able to dance to this tune! 

Below is what results when the Alt is not solidly one with the SW-EM bracket, this MUST BE CHECKED FOR at assembly, and must not be allowed!  Often, a loose condition does reveal itself, even if it develops sometime later, as will be associated with vibration or rattling noises.  Note that often, because of the variable nature of resonant conditions occurring due to variable conditions, these vibrations are more pronounced or only occur at certain RPMs.  Friendly warning:  If you don't take note of the associated noises, or take note of them and "just turn the radio up", eventually things will break!

Tip:  Listen for "new noises" and investigate them!  Luckily, Dennis N. caught the condition shown below, before it completely let go, but from the amount to wear evident in the Alt pivot, it was well on its way to that.  [He must have really had the tunes "turned up"] 

He sorted it by replacing separated Motor Mounts, by replacing the worn Alt housing, and by checking for solid mounting on reassembly.    

Result of an Alt, loose on the SW-EM bracket!    
Displacement is approaching being equal to the pivot bolt diameter!! 
Dennis Needham picture posted with permission.


Loose Fanbelt Tensioning Bar Threads in Cylinder Head:

The OE Fanbelt Tensioning Bar is reused when installing the SW-EM Alt kit. It is important for keeping tension of Fanbelt at the adjusted level, and it is subjected to much the same vibrations Fanbelt is imparting to rest of the Alt mounting system.  The securing bolt on one of my Alt installations has twice backed out and been completely missing(!), and noticed at the next under-hood inspection.  I have also had feedback of this occurring on two customer cars. Thankfully, I discovered this on my own car when investigating "new noises", and before any secondary damage resulted.   

Maybe the threads in Cyl Head were loose or sloppy, [I know the bolt was properly tightened!] maybe conditions were just optimum for this loosening to occur, but it certainly must be permanently prevented!  This could be simply done by applying a thread-locking compound...but that is not immediately visible and solution was to drill and safety-wire the bolt.  A safety-wire is obvious and clearly visible!  Ref:      

Delco Alt Installation on SW-EM Kit bracket showing 1/2" "S" bend deviation from straight shown in Yellow,
required in Fanbelt Tensioning Bar to allow good alignment with threaded boss on Alt Housing. 

Richard G. fedback another solution, which I find possibly susceptible for the reason given below...

Richard G. picture posted with his kind permission.

Richard's Fanbelt Tensioning Bar was one of the thicker styles fitted, so instead of trying to make the "S" bend, he spaced the Cyl Head mounting surface out with a stack of washers (he also retained the dual rubber shock-mount) .  I warned him this could exacerbate the self-loosening of the bolt.  

Excerpt of my e-mail exchange with Richard:

"Spaced out like that, you clearly don't need the "S" bend, but beware, I have had two reports of that securing bolt into the Cyl Head loosening, and I have personally experienced this also, finding the bolt missing completely (twice!) when investigating the accompanying noise...I believe the spacer solution would likely exacerbate this possibility of this happening, because of the "overhanging mass" of the bolt and so many washers, so I advise at the very least, to keep an eye on it! 

After loosing the second bolt, I figured the threaded hole in the Cyl Head was loose, or that there was a high concentration of vibration at that location...either way, a more positive help was required...I suppose a chemical threadlocker would have also been an option, but knowing these loose their effectiveness with elevated temperatures, which are certainly present at the Cyl Head, my solution was to safety-wire the replacement in place (which is also immediately inspectable!), for absolute security and peace of mind.  This solution has served without failure in the long-term.


Alternator Output Rating Discussion (reposted from FB): 

This discussion is interesting and informative for anyone considering an Alt conversion, and wondering about the output rating of the Alt.  The intent here is to show questions, answers, and points of discussion. Since these are screenshots (and therefore a snapshot in time), postings by individuals which might have occurred after the screenshot was made, will obviously not be shown.

For reference, 12V X 60A = 720W...and one horsepower is equivalent to 746W, so at maximum electrical output, a 60A Alt puts about 1 HP of mechanical load on the Crankshaft by way of the Fanbelt (we use the term about, because there are no inefficiencies accounted for, in this Rule-of-Thumb). 

My recommendation continues to be against fitting an Alternator with rating more than ~60A, because with a Chaging System rated at this magnitude, existing mechanicals and wiring do not need major uprating.  If someone's elec requirements are that they indeed need more power available, it can certainly be accommodated, but further engineering would be necessary in order to assure safety and reliability of the installation.  I therefore stand by my statements and recommendation made herein, and I presume everyone else posting does also, but if anyone does not like the republishing of their names here, let me know and I'll remove it. 

Link to SW-EM Electrical Ramblings shown here.


Squealing Fanbelt on SW-EM Alt Kit installation after adding Fog Lights

[Excerpt of an e-mail exchange with an installer of the Alt conversion: ]

He asks:  "...never had an issue before I installed aux fog lights. It seems that I get a squeal only when I turn on the fog lights."  

My response:   " ...this is not too much of a surprise! 

A squealing Fanbelt is due to is slipping, and since the additional electrical load of high current loads placed on the elec sys is effectively transferred to the Alt by way of the Fanbelt, it might certainly squeal when turning the ON Fog Lights!  Remember, once engine is started Charging Sys supplies ALL elec requirements, from recharging the recently partially discharged Battery, to ALL elec Loads you have switched ON.  [Battery supplying power while engine is running is an unusual situation and means something is wrong...from Chg Sys output being insufficient, to too many Loads being turned ON and requiring power.]

I wonder, and wouldn't be surprised if it also squealed for a few seconds after engine start even without the Fog Lights ON...the additional load is from the Battery (Starting energy having pulled SOME energy out of the Battery, partly discharging it).  Don't forget Fanbelt tension is a fine dance and compromise between being loose and slipping/squealing under high load circumstances, and being unnecessarily too tight and causing Water Pump bearing wear or even worse, causing the sheetmetal WaPu Pulley to fatigue and fail and this: 

Ideally, the Belt tension should be just tight enough to transfer, without slipping/squealing, the highest elec Load which occurs, and no tighter, which would cause higher wear and tear than necessary...(hence my "fine dance" comment).  [...and yes, I am aware that this is the fourth(!) time this picture is being shown on this page!]

Since you have installed Fog Lights, your Fanbelt must apparently be adjusted a bit tighter!  

I recommend the following (ALL with engine OFF, and NOT running!):  Adjust Tension of Fanbelt just a bit tighter, and possibly inspect and deglaze pulley contact surface of Fanbelt a bit with emery cloth if it looks totally glassy, or even replace/renew the Belt.

To adjust, loosen the Tensioning Bar locking bolt on top, and also Pivot bolt (3/8" Allen) below (it does have a locking nut behind bracket which should also be slightly loosened first, access is from below!), just slightly and just enough to allow pivoting of Alt, and using a long lever between engine block and Alt housing, lever the Alt housing away from engine to tighten (BUT NOT OVER-TIGHTEN!) the Belt (yes, there is some judgment called for here!)...tighten the Belt adjustment bolt on top when at a reasonable belt tension is achieved, and also the lower Pivot bolt.  Recheck tension, and if necessary retighten Pivot if any movement between Alt and Bracket, or Bracket and engine block is noted when giving the Alt a strong tug by hand!  NO MOVEMENT SHOULD BE POSSIBLE AND/OR OBSERVED! 

After assuring engine is safe to start, Start engine and note if any squealing occurs immediately after Start, or when turning ON Fog Lights or other high elec loads. Make adjustments as necessary...remember, Pivot bolt allows pivoting, and Bolt on tension bar locks it in place...BOTH should be loosened to allow adjustment, and MUST bet tightened to prevent ANY kind of movement, including slight, when finished.  Alt MUST NOT BE ABLE TO MOVE...the Fanbelt is the ONLY thing which does any moving!!!  When satisfied with Fanbelt adjustment, tighten Pivotbolt Locknut. 

There is nothing wrong with learning!...everybody learned at some point...and ALL of us should strive to continue to learn! So when doing this work yourself, Work Safely!...especially around moving parts of the running engine!  Also remember that the B+ terminal on the back of Alt is directly connected to Battery, so DO NOT inadvertently connect it to chassis with a metal wrench!  BIG sparks would result!  If necessary, to prevent such an inadvertent excitement, temporarily disconnect Battery while making Alt adjustments. 

Work Safely!  "


Remote Voltage Sensing Installation Variation

The SW-EM Alt kit harness ties the Voltage Sensing input of the Delco Alt VReg (Terminal 2), directly to  Alt B+ output terminal, with a short jumper, because in the typical installation in the Volvo vehicles, the length of the wire between the Alt and vehicle Bat is less than three or four feet (of a heavy gauge cable), so the voltage drop which occurs across this minimal Resistance due to cable length and other currents flowing through this path, is quite small and can practically be ignored.  This implementation is called "Local Voltage Sensing".   

In vehicles where this distance is significantly longer, like a B18/20 installation in a boat, or remotely from engine compartment in a trunk, in order for the VReg to get a more accurate sense of the Battery Voltage (not the voltage some cable length/Resistance/Voltage away, which will be more influenced by other currents), the VSense can be relocated from the Alt B+ terminal, right to the +Battery Clamp with a separate 14ga wire, as shown below.  

Again, "Remote Voltage Sensing" is not necessary in the typical Volvo installation, but I thought I would show and explain the difference.    

 In this excerpt of SW-EM Alt Kit Installation Diagram, the normal Red wire used for Local V Sensing is removed,
and replaced with the Orange connection from Alt Sens (Term 2) to Battery + terminal, to implement Remote V sensing.

See also:


Alt Kit not as shown in Alt Kit Description Page: 

An eagle eyed Chuck S. noticed when he received his Alt Kit, that the Pivot Bolt was different than that shown on the Alt Kit Description Page.

Excerpt from the Alt kit picture in question.


He writes:  "Your website examples show the bracket using a hex head bolt.  It is not the black metal [black oxide finish of the H-K pivot bolt] of the strongest metal available.
Also, the bolt is does not include the nylon lock nut."

My response:   "Chuck; 

Good eye!  The pictures on the site indeed show the Alt secured with a standard Hex bolt and no locking nut.  These are early pictures before I specified the better [superior!] H-K pivot bolt, plus Nylock securing nut.  As a point of information, it was never fed back to me that the earlier configuration bolt had failed, or was not good enough in any way, but by changing to the better, longer H-K bolt, and adding the Nylock nut, my intent was to add even more safety margin, with a goal of ZERO failures!  As it was, there have been several failures, one even of the H-K bolt, but in ABSOLUTELY EVERY CASE, the failures were directly traceable back to improper (loose!) mounting!  See also: 

The kit has been engineered with good practices, lots of margin, and it comes with the knowledge, and actual field experience, that others with installations just like it, have literally THOUSANDS of trouble-free miles behind them, when it was installed per the recommendations, but in the end, particularly if they deviate from recommendations, it goes without saying that the installer is always responsible for the installation in the long-run...  "


Stealth Alternator Installation!: 

Australian John Johnson pictures from Faceplant, Volvo Amazon subpage (pictures are actually of an 1800), used with his kind permission.  

John clearly likes his chrome, but also an otherwise original (looking) configuration, even though he has an Alternator installed (actually, he notes, it is a Generator housing internally modified into an Alternator, so a real "Stealth Alternator Installation", and not a SW-EM Alt Kit!  I have requested details on this!).  Although the wiring is functionally consistent with the SW-EM conversion, his implementation is clearly an expert level modification which would take longer to implement! 


A peek into the shiny VReg shows the original internals have been completely removed and replaced with a simple soldered jumper, which directly connects what was the Generator (now Alt!) Output, D+ terminal, to the Battery, B+ terminal, effectively bypassing the former Cut-out Contact, which is of course, no longer necessary with an Alt. 


Excerpt from 122 Wiring Diagram (Color codes for the 1800 added in Turquoise!), showing Charging System, and associated, also wiring changes which allow a gutted and modified VReg (Charging Control) to stay in place for an original appearance, after an Alt conversion  has been performed.  Even the original sleeved three wire harness (Blue), between VReg and former Gen, can be repurposed and reused.  Red highlighted area, wiring and connections are IN. Yellow highlighted area, wiring and connections are OUT. 

Note that wire jumper inside VReg is carrying the Alt output current, so must have a similar heavy wire gauge as the other conductors in the path:  (6mm2) 10AWG.  See Reference Info below.

Note also that the VSensing (Terminal 2) of the Alt Connector is again directly connected to the B+ output terminal for Local Voltage Sensing



Unusual Alternator installation, using dual-groove Crankpulley By apparently using the cast-in pivot of the B20, with a Delco Alt, a previous owner/installer was able to (at least partially) compensate for the pulley offset, by using a dual-groove Crankpulley and two separate Belts.  [Current owner has not gotten back to me with additional details...I'd love to see a detail of the pivot and mount!]

Nathan Courtright FB picture, permission requested (he said he would get more, better pix):

One Fanbelt for Waterpump, one Fanbelt for Alt...hmmm!

Excerpt of my exchange with new owner:

"In studying your pic further, I see what's happening...and it's pretty interesting, as it is quite unusual!! ...someone has used the outer groove of a double Crankpulley to run just the Alt mounted on OE Alt pivot of engine. They have not done the typical hacking away of the Alt housing to give alignment (good!), however, since the 1/2" pivot bolt must be used in the block, the hole in the Delco Alt had to be enlarged (less than good!), and a separate Fanbelt had to be fitted, only driving the Alt. There still appears to exist some misalignment, so I expect accelerated Fanbelt wear on that one to some extent. what you are trying to do by fitting a double groove WaPu Pulley would allow you to run a single belt, however, it would not address the misalignment still present. Some more pix would still be good...including one showing plane of Belt. 

[And now that I think about it some more, I must ask:  How is the WaPu Belt tension adjusted?...this is normally done by varying the Alt position, but with separate Belts, now there is no provision for it??]  

This is a definite candidate for my "Special Engineering by a PO Page"!


Turnbuckle Fanbelt Tensioner: 

Picture of a Alt installed on the Distributor's not on a SW-EM Alt Kit, but I though I would show it here as it is a nice solution...

Distributor side (Bosch) Alt Mount with Turnbuckle Belt Tensioner...also applicable to the Manifold side mount Delco conversion!  Permission requested. 

My response to posters, most of whom did not like this arrangement, suggesting it was not up to the job.

" Contrary to some posters who think its not strong enough...I like it, and I'm even looking at adding such a feature option to my Alt Kit, because it allows precise and less rustic setting of the Fanbelt more levering between the Alt and engine with a tire-iron or big screwdriver!

To those who don't think it will be strong enough, I remind them that this link only locates the top of Alt for the purpose of setting Fanbelt tension...and AFTER Fanbelt tension has been set, the Pivot below should be tightened and locked to hold the entire mass of Alt in place...point of fact, this link could be removed after pivot is locked (not that this is recommended, but strictly looking at this from a standpoint of mechanical analysis!)...Alt mass is NOT supported by this link normally...only IF the pivot loosens or is not tight for other reasons!  That's why link should obviously be present and its locking nuts is a BACK-UP, but not the primary securing feature! "



Reference info:  

Wire gauge AWG to mm2 chart, excerpt from:


External material sources are attributed.  Otherwise, this article is Copyright © 2005-2023.  Ronald Kwas.   The terms Volvo, Bosch, A-C, Delco, or Delco-Remy, are used for reference only.  I have no affiliation with any of these companies other than to try to keep their products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here.  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, at the reader's discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles and future! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you don’t, you’re just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the odd metaphor and probably wise-a** comment. 


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