Belts

[Raymond W.]

I'd like to replace the belts on my car, but before I do, there are a couple of questions that I've raised as I begin this search:

1. Who is the best source from where to purchase the most accurate/correctly reproduced GM belts...Quanta?
2. Are these the correct GM Part #'s: Alternator 9433658, Smog Pump 9433611, AC 9433751, Water Pump 3952326...?
3. What would be the correct "quarter" date code for a car with the build date of Jan.11,1974 (4th Qtr 1973 or 1st Qtr 1974?

Are there any other points that I should be aware of...

Thanks.

[Michael W.]

Re: Belts

You might tell us year of car you've got, and what engine transmission/options. I'll guess by the build date of Jan11, 74 that it's a '74.

Unless you're going into Flight Judging, I wouldn't bother with the Quanta repo belts. Modern style cogged belts are much more reliable and tend to stay put in the grooves to a higher degree than the repos.

Regarding date codes, 3rd quarter '73 would be the most credible from the judging standpoint. Expecting all belts to be have been made, delivered, and installed on a Jan. 11th car with a 1Q74 date code is a bit of a stretch. And nobody likes stretched belts.

[Raymond W.]

Re: Belts

Mike,

I have a 1974 Coupe, 454, 4speed, AC, manual steering. My intentions are with Flight Judging in mind.

Thanks,
Ray

[Joe L.]

Re: Belts

Ray-----

I would say that Quanta is probably about the best reproduction source for "authentic" drive belts. However, their products are sold by many other Corvette vendors. 1973 and later Corvettes used belts of "cut" construction, which is functionally prefereable to the "wrapped" type belts used earlier in PRODUCTION.

I agree with your alternator and water pump PRODUCTION belt part numbers. However, I believe that the AIR pump and A/C compressor were driven off the same belt in circuit with the forward groove on the waterpump pulley. I have not been able to find a part number that I feel confident about for this belt. Quanta should know, though.

[Joe L.]

Re: Belts

Ray-----

Another question for you: what is the part number stamped on your waterpump pulley and also the number of grooves and OD of that pulley?

[Raymond W.]

Re: Belts

Joe,

I can't seem to locate a part number on the waterpump pulley. The pulley has 3 grooves and the OD is about 5". The car has no AIR pump. The AC is run on the forward groove, the Alt. is run on the middle groove, and there is a small belt on the rear groove & crank with slight tension being applied to it from an idler pulley wheel (I acquired it like this...not sure of the how's and why's of that set up). Eventually, I do have intentions of installing the AIR pump.

Thanks,
Ray

[Joe L.]

Re: Belts

Ray-----

I don't know if the pulley had a part number stamped on it, or not. However, the 1974 Corvette with LS-4 and C-60 waterpump pulley was unique to that application and for that year only. I'm very curious to know how it differed from the pulley used for non-AC LS-4 applications and all 1971-73 LS-5/LS-4 applications. The other pulley was of 3 grooves and 5-1/2" OD.

So, if you could scutinize the pulley for a possibly lightly stamped part number and get a more-or-less precise measure of OD, that would be of great interest to me.

[Raymond W.]

Re: Belts

Joe,

I'll see what I can do to get a more accurate measurement. The calipers I have can't quite extend far enough to the widest point of the pully. I'll keep trying.

Ray

[Joe L.]

Re: Belts

Ray----

It doesn't have to be precise to the .001". I just didn't know if the 5" dimension you mentioned was an "eye-balling it" sort of thing or if you had otherwise measured it.

[Raymond W.]

Re: Belts

Joe,

It was measured and would fall between 4 7/8" to 5". Hope this helps.

Thanks again...
Ray

[Joe L.]

Re: Belts

Ray-----

That's fine. It establishes that the difference between the 1971-73 all big block/ 1974 big block without A/C pulley from the 1974 big block with A/C pulley is OD-----the former is 5-1/2" OD and the latter is about 4-7/8"-5" OD.

It's amazing to me, though, that GM created a new and distinct pulley for the 1974 with big block and A/C application. That pulley, GM #336097, was used ONLY for the 1974 Corvette with big block and A/C application; it had absolutely no other applications, at all.

For 71-73, as I say, the same waterpump pulley was used for all big blocks, A/C or not. So, there must have been some problem associated with big block A/C applications that prompted the change for 1974. This change would have affected the speed of the waterpump pulley since the crank pulley was not also changed.

It should also affect the length of the captive belt. However, I show that the 71-74 applications used the GM #3952336 belt. I don't understand how this would be possible, though, if the 1974 big block with A/C used a smaller pulley. That should have necessitated a slightly shorter belt. However, thinking more about it, the big block with A/C application also used a belt tensioner. So, the difference may have been taken up by the tensioner.