Author Topic: '67 429 Belt Drive  (Read 2453 times)

Offline JVA

  • Posts: 104
  • Name: Justin VanAbrahams
'67 429 Belt Drive
« on: February 07, 2014, 11:15:48 PM »
In looking at the service manual for '67 Cadillacs, it appears that El Dorados had a duplex alternator belt - a pair of belts wrapping around the crank, water pump, AC compressor, and alternator - and then a single belt around the crank, water pump, and P/S pump. Is that true? Is there a a feasible way to retrofit that onto a RWD car? Or, alternatively, another interesting way of getting to a duplex alternator belt?

Offline Scot Minesinger

  • Posts: 6004
Re: '67 429 Belt Drive
« Reply #1 on: February 08, 2014, 07:48:37 PM »
In 1968 Cadillac went to dual belts on the a/c and power steering with the 472 engine, which was necessary.  Never seen dual belts on an alternator.  You asked about converting from one to two belts on a 67 RWD for the alternator, and of course anything can be done for a price.  To make such a conversion can be expensive, and parts are likely custom made.  It does not seem worthwhile, one belt is fine for the alternator.  I agree the a/c could use another belt, but you can buy one of those special green belts (paint it black) from NAPA that is heavy duty and will work better on the a/c.  You could do this for the alternator too.  I find myself using them for one belt a/c applications as otherwise the belts often squeal.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline TJ Hopland

  • Posts: 10183
Re: '67 429 Belt Drive
« Reply #2 on: February 08, 2014, 07:57:44 PM »
What made a 67 Eldo different than the other 67's belt driven accessory wise?   

Most of my experience is on the 71-78 where I don't think there was a difference in the belt stuff FWD vs RWD.  Was there something different about the 67-70's belt wise?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline Scot Minesinger

  • Posts: 6004
Re: '67 429 Belt Drive
« Reply #3 on: February 08, 2014, 09:57:33 PM »
I have worked on Eldorados from the 60's and early 70's and never seen a double belt drive alternator
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline The Tassie Devil(le)

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  • CLC Number: 18992
  • Name: Bruce Reynolds
Re: '67 429 Belt Drive
« Reply #4 on: February 08, 2014, 10:22:46 PM »
I have a double belt drive on the Alternator on my '72 Eldo, but only one of the "V"'s is used.

Must have been replaced some time before I purchased the car.   Don't know what it is off.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Offline TJ Hopland

  • Posts: 10183
Re: '67 429 Belt Drive
« Reply #5 on: February 09, 2014, 10:06:26 AM »
Looking at pictures online it kinda looks like the typical 429 setup the alternator belt does not go over the AC.  Looks to be 3 grooves on the crank and water pump so each device gets its own belt?   On the 67 Eldo it looks like the AC compressor is shifted back and maybe lower and then the same belt goes over AC and alt?  Guessing they did this because the Eldo engine sits higher and more forward than the RWD cars so the AC in its typical location was kinda causing clearance issues?   Looking at the angles with that setup there is not much wrap on the alternator pulley so I could see that they did the double belt just to get as much contact area as they could.  It may have been the cheapest fix especially since they knew it was going to be a 1 year only thing.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline JVA

  • Posts: 104
  • Name: Justin VanAbrahams
Re: '67 429 Belt Drive
« Reply #6 on: February 09, 2014, 01:59:51 PM »
TJ, you're exactly right about the difference in the drive. I gotta believe that '67 429 El Dorado is a very rare configuration indeed, being just one year.

Here is the photo from the FSM - the text describes what is seem in the picture:



There is very little wrap on the alternator indeed... but I'm wondering if the effective contact area is less or more than the regular, single-belt setup on other 429s. I was hoping someone might be able to comment.

Offline TJ Hopland

  • Posts: 10183
Re: '67 429 Belt Drive
« Reply #7 on: February 09, 2014, 04:20:41 PM »
Without a car or manual to look at I'm just guessing but it appears to me that the 'regular' setup was the inside belt was crank - water pump - power steering.   Middle groove was crank - water pump - alternator.   Outside was crank - water pump - AC.     Because in this design the alternator belt did not also go up and over the AC there was decent wrap on the alternator pulley.

For what ever reason in the Eldo they changed things, possibly hood or radiator clearance issues?  Assuming nothing else has changed (other pulley spacing) the AC compressor appears to have been moved back one belt width.  Assuming its the same as later ones the inner groove on the dual groove is in the same position as the single grooves so they moved the compressor back to the mid groove.  Running the alternator belt up and over the AC reduced the wrap on the alternator.   I imagine one option would have been to move the alternator forward and let it use its own belt in the forward groove?  But maybe that also caused clearance issues (like the alternator fan hitting the AC belt) not to mention possibly expensive to make new brackets for 1 model 1 year?  Dual groove AC either already existed or was going to exist the next year so that's easy.  Dual alternator pulley if it didn't already exist would have been fairly easy to make.

Just a theory based on me not wanting to actually get off the couch and computer today and get more important things done.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline JVA

  • Posts: 104
  • Name: Justin VanAbrahams
Re: '67 429 Belt Drive
« Reply #8 on: February 09, 2014, 04:50:35 PM »
Without a car or manual to look at I'm just guessing but it appears to me that the 'regular' setup was the inside belt was crank - water pump - power steering.   Middle groove was crank - water pump - alternator.   Outside was crank - water pump - AC.     Because in this design the alternator belt did not also go up and over the AC there was decent wrap on the alternator pulley.

It's actually worse than that. The crank pulley is only two grooves, and drives (1) the water pump and AC, and (2) the water pump and PS. The alternator is driven by a third belt, on a 3rd groove, by the water pump. It's an inane arrangement.

Quote
For what ever reason in the Eldo they changed things, possibly hood or radiator clearance issues?

Yeah, I dunno. I'm not sure what they did or why, but here's what it looks like on the other 429s:



Quote
Just a theory based on me not wanting to actually get off the couch and computer today and get more important things done.

Right there with you. It's wet and nasty outside, and I'm not having it.

Offline TJ Hopland

  • Posts: 10183
Re: '67 429 Belt Drive
« Reply #9 on: February 09, 2014, 05:20:52 PM »
That makes a little more sense that the AC got moved back 2 grooves, 1 you would not think would have made that much difference but two would be at least an inch if not a little more. 

I see you have the 2 groove alt pulley.   Wonder if because of the Eldo they just try to list all 67 Cad's as the same dual?

Not sure why but GM seemed to do the drive the alternator from the water pump but not off the crank a lot.  The 'smog' 472-500-425-368 and I think the 4100's were like that except front groove instead of rear.   Oldsmobile did that on and off.  As long as the cars had AC that gave them 2 belts to drive the water pump so I suppose they figured that was enough to keep the water pump turning.  I wonder if it was because the alt had such a small pulley and they were trying to get more wrap?  Just going around 2 pulleys would get more wrap than hitting 3.   In most cases they would not have been able to clear the water pump if they tried to go alt to crank direct.   With these apparent issues especially with growing alternator capacities its kinda amazing they did not come up with the serp belt idea sooner.   They are a maze but if you look at em they do get a good wrap on all the pulleys. 

« Last Edit: February 09, 2014, 05:22:26 PM by TJ Hopland »
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

 

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