57 WATER PUMP PULLEY

[Bruce B.]

What is the correct waterpump pulley for an early 57, 250HP fuel car with a Powerglide trans?
Thanks in advance.

[Mike M.]

Re: 57 WATER PUMP PULLEY

production (original) pulleys were NOT stamped, whereas the NORS spare i have does contain a part #. otherwise they are identical. judges look for absence of part #. the service replacements were available in the 70's when i got the spare i've got. i'm doing an early 57 250 powerglide, vin 1093. what is your vin? mike

[Roy B.]

Re: 57 WATER PUMP PULLEY

Bell type not step down.

[Bruce B.]

Re: 57 WATER PUMP PULLEY

Mike; My 57 is #809.

[Joe L.]

Re: 57 WATER PUMP PULLEY

Bruce-----

I believe that the pulley originally used was GM #3704172. That pulley was discontinued and replaced by GM #3905995 in April, 1973. The latter pulley was discontinued without supercession a few years ago.

Some confusion on the correct pulley exists because 2 different pullies were used for 1957. The other pulley, GM #3713974, was used for engines with the Duntov cam and either 2 X 4 or FI. However, I believe that the 250 hp with FI used the 3704172.

[Mike M.]

Re: 57 WATER PUMP PULLEY

joe and roy: our 57 pass 250 hp, the engine of which had never been removed or torn down prior to my restoring the old girl, has a stepped pulley without any stamping numerics. i'm 99.9% certain this is the pulley installed on the engine from the git go. i believe all the service replacement stepped pulleys were numeric-stamped. my NORS pulley, # 3827846 whcih the 1978 parts book service replaced the original 57 22x4 and fi step-pulleys, is nearly identical to the original pulley on our 210 post 250hp chevy but the NORS pulley is stamped 3827846. more confusion. regards, mike

[Bruce B.]

Re: 57 WATER PUMP PULLEY

Mike, Joe & Roy;
I have a 3713974 which was with the engine but my concern is that is is a wide deep groove pulley which I thought was used only on the solid lifter engines.
I also have smooth (not stepped, narrow groove) unstamped pulley which lines up correctly.
Thanks for all the info.
Bruce B

[Mike M.]

Re: 57 WATER PUMP PULLEY

bruce et al: i have a nos fan belt, in the old yellow and black GM envelope, part # 3738437. its not a wide v-belt( its 3/8" width) for the narrow groove pulley. on page 208 of the march 1958 parts book, this belt is called for on 57 pass car with FI and it doesn't specify for 250 or 283 HP engines so it gets more confusing..mike

[Roy B.]

Re: 57 WATER PUMP PULLEY

MY all original 57 I had for 32 years I got when it was 10 years old, had the deep (wide belt)pulleys,water pump was the bell type, It was a FI-P/T-P/W-Auto- that no few at the time ever knew they made. I remember people telling my I must have added the power top from JC Whitney. Times have changed!!!

[Joe L.]

Re: 57 WATER PUMP PULLEY

Mike-----

Well, these C1 questions always confound me. A big part of the problem is that I have practically "0" hands-on experience with C1's.

Anyway, GM information on the pullies used for 1957 is somewhat contradictory and confusing. The pulley used for 1957 "except 2X4 and FI" was supposed to be GM #3704172. This later became GM #3905995 for SERVICE. The pulley used for 1957 "with 2X4 and with FI" was supposed to be GM #3713974. This later became GM #3827846 for SERVICE.

However, other references say that the pulley for "except mechanical lifter, hi-lift cam" was the 3704172 and for "with mechanical lifters, hi-lift cam" GM #3713974. Of course, the "with mechanical lifter" engines were the 270 and 283 hp and the "except mechanical lifter, hi-lift cam" were the 220, 245, and 250 hp.

Actually, I believe that the main difference between the 2 pullies is that the 3704172 has a "shallow" belt groove and the 3713974 is "deep groove". I'm not sure about nose configuration.

Other than the above, I believe that the pullies are interchangeable since the offset and diameter are the same. As a matter of fact, the only difference between the belts for the 2 pullies is that the belt used for the pulley system with the 3704172 was 54-3/4" long and the belt for the pulley system with the 3713974 was 54-1/8" long. That's undoubtedly because the belt would ride a little lower in the groove of the "deep groove" pulley system, so a slightly shorter belt was required.

In general, GM used "deep groove" pullies for "high winding" engines. So, it would seem logical, then, that for 1957, they would have used the standard groove pullies for the 220, 245, and 250 hp engines and the "deep groove" for the 270 and 283 hp. However, it may well be that they just used the "deep groove" for all applications except base engine. After all, from 1958-62, I believe that they used deep groove pullies for all Corvette applications.

I can't reach into my parts collection for help on this one; I've never really gotten into buying C1 parts so "my cupboard is nearly bare".