1962 Corvette 340 Hp Question

[Bruce B.]

What are the correct part numbers for the crankshaft and water pump pulleys for a 340 hp engine.
The correct harmonic balancer should be pn 3817173.
The car is sn 5815.
Thanks.

[Joe L.]

Re: 1962 Corvette 340 Hp Question

What are the correct part numbers for the crankshaft and water pump pulleys for a 340 hp engine.
The correct harmonic balancer should be pn 3817173.
The car is sn 5815.
Thanks.

Bruce-----

I believe the crankshaft pulley was GM #3766987.

As far as the waterpump pulley goes, I think that 2 different ones were used. I believe the early pulley was GM #3724816. The later pulley was GM #3770245. However, I do not know when the change occurred. In fact, I'm not even 100% sure that both were actually used in PRODUCTION.

The GM #3766987 was replaced many years ago by the GM #3858533 which remains available from GM to this very day. The GM #3724816 was discontinued without supercession in October, 1984. The 3770245 survived until just a few years ago but is now discontinued, too.

I believe that all of the original pullies are available in reproduction, though.

[Terry D.]

Re: 1962 Corvette 340 Hp Question

Bruce
As per the Judging manual, Water pump pulley is #3724816 and Crank pulley is #3756328.
Terry

[John D.]

Re: 1962 Corvette 340 Hp Question

Is the 62 crankshaft pulley the same as the 63 HHP pulley. If so the one from GM that has been available forever is incorrect. JD

[Bruce B.]

Re: 1962 Corvette 340 Hp Question

Thanks guys.
I ordered a 3858533 recently from GM and found out that it will not fit on the 3817173 balancer (I tried it on 2 of them). The raised area on the back of it is about 1 1/4" OD and the hole in the balancer is about 1 3/16". In addition it is a double pulley and I think the correct one is a single belt pulley.
Terry, I think the 3756328 you described is a single for a belt.
John, is the 63 340 HP pulley a single or is it double for use with a idler system?
I'm stilled confused but Terrys numbers look good.

[Terry D.]

Re: 1962 Corvette 340 Hp Question

Bruce
Those are the numbers on my pulleys and it is a 340hp. I agree with you that the 63's have got to be different because of the idler pulley and the extra options offered in 63 that were not available in 62.
Terry

[Mike M.]

Re: 1962 Corvette 340 Hp Question

the 62 340 and 360 hp harm bal pulley is a single groove pulley. the 63 360 hp harm bal pulley is a double groove pulley.mike

[Joe L.]

Re: 1962 Corvette 340 Hp Question

Bruce
As per the Judging manual, Water pump pulley is #3724816 and Crank pulley is #3756328.
Terry

Terry------


I believe the 3756328 was the pulley used for 250 and 300 hp applications. I don't think it's a deep groove pulley.

However, the information I'm providing here is strictly GM information; it might not be actually how the cars were built. I have no personal experience with 62 Corvettes.

[Mike M.]

Re: 1962 Corvette 340 Hp Question

the 62 340 and 360 harm bal pulley was not only a single groove, it was also a deep groove. mike

[Joe L.]

Re: 1962 Corvette 340 Hp Question

the 62 340 and 360 hp harm bal pulley is a single groove pulley. the 63 360 hp harm bal pulley is a double groove pulley.mike

Mike------


That being the case, then the 62 340 hp and 360 hp could not have originally used the 3766987 crank pulley since it's a 2 groove pulley.

So, it sounds like the 250/300 hp engines must have used the same pulley system as the 340/360 hp.

[Joe L.]

Re: 1962 Corvette 340 Hp Question

Is the 62 crankshaft pulley the same as the 63 HHP pulley. If so the one from GM that has been available forever is incorrect. JD

John------


There were at least 2 different styles of the 3817173 balancer. The original style had a different "face" design than the later. This may be why the 3858533 will not fit properly with the original style.

From what I can determine, 1962 through, at least, 1964 Corvettes used the original style balancer. 1963-64 (but, apparently, NOT 1962) used pulley GM #3766987. So, apparently, the 3766987 and the original style balancer are compatible.

For 1965 SHP the crank pulley changed to the 3858533. So, if the 3858533 is not compatible with the original style 3817173 balancer, then the style of the balancer face must have changed at that time, too.

Here's the interesting thing here: I THINK the style of the 3817173 balancer face changed at the same time as the style of the rear changed (from "finned" to non-finned). If I'm correct, then the original 65+ 3817173 balancers should have been the non-finned style. Of course, there might have been ANOTHER design of the balancer which incorporated the 65+ face with the 62-64 "finned" rear.

If 65-68 used the same style balancer face as 62-64 and if, as you describe, the 3858533 is not compatible for installation on that design, then I don't see how the 3858533 could have been used for 65-68. However, as far as I know, its use on 65-68 applications is not in question.

Attached are photos of an original design 3817173 balancer (top of photo) and a balancer of the same general configuration as a later design 3817173 balancer (bottom of photo).

[Larry C.]

Re: 1962 Corvette 340 Hp Question

For whatever it's worth, my original 1962 340 hp engine has crankshaft pulley #3756328 and water pump pulley #3724816. Both single groove, of course. This car is mid-June 1962 production.

[John D.]

Re: 1962 Corvette 340 Hp Question

Joe & Mike, etc. The service replacement 63 up crankshaft pulley with the dual groove has at least three minus factors. #1. Either the OD of the pulley or the depth of the grooves is off because if you use a stock fan belt with the SR pulley the adjustment (at the alternator stick) is clear out to the end of the slot.
#2. The SR replacement pulley has a reinforced "bead" close to the grooves. Joe calls this the face of the pulley. A stock OEM pulley does not have this "bead" but is smooth across the face. The original pulley though does not have the guts as the service replacment in that the face part of the pulley is tack welded to the grooved part.
#3. Sharp chassis judges at the big shows are dinging car owners for having the incorrect pulley.
My 63, the LWC has a service replacment pulley on it. Car was judged 3 times. But only dinged one time. Seems a certain MD missed the fake pulley. Real deal is in nice box waiting to go on except with no lift it's too hard for me to do.

[Bruce B.]

Re: 1962 Corvette 340 Hp Question

Thanks to everyone for the great information.
I just checked my old stuff and came up with this information.
I have 2 balancers pn 3817173, they are both of similar configuration but not exact and they are dated G63 (July 1963) and F66 (June 1966). The orange one is the 1966 one in the attached pictures.

The new 3858533 pulley does not fit either balancer.

While looking through my parts I found 2 3756328 pulleys. They are both stamped with the pn, one on the front and one on the back side. They fit the balancer perfectly.
I also found 2 waterpump pulleys pn 3724816 GM with a "Z" stamped on them also.
All 4 pulleys have belt grooves about 0.625" deep and about 0.550" wide at the top inner edge.

I guess today was my lucky day, got the good information and also found 2 sets of the parts.
I guess I will have to look for other stuff at Kissimmee.

[Joe L.]

Re: 1962 Corvette 340 Hp Question

Thanks to everyone for the great information.
I just checked my old stuff and came up with this information.
I have 2 balancers pn 3817173, they are both of similar configuration but not exact and they are dated G63 (July 1963) and F66 (June 1966). The orange one is the 1966 one in the attached pictures.

The new 3858533 pulley does not fit either balancer.

While looking through my parts I found 2 3756328 pulleys. They are both stamped with the pn, one on the front and one on the back side. They fit the balancer perfectly.
I also found 2 waterpump pulleys pn 3724816 GM with a "Z" stamped on them also.
All 4 pulleys have belt grooves about 0.625" deep and about 0.550" wide at the top inner edge.

I guess today was my lucky day, got the good information and also found 2 sets of the parts.
I guess I will have to look for other stuff at Kissimmee.

Bruce------


What creates the problem with the fitment of the 3858533 mounting to the original style 3817173 balancer?