57 Water Pump pulley depth

[Gerry P.]

The water pump pulley on my '57 245hp has a bit of a wobble. I'm hoping it's just the pulley and not the water pump.

I have another pulley but am not sure if it is correct. Before going to the effort to pull off the old one, I would like be sure my replacement is ok to use. The depth of my spare is 2-54/64" (2.84375) as measured sitting on the bench from top to bottom (outside to outside). The diameter is 7 1/8". Does someone have the correct measurements for a '57? Or in the alternative, does someone know of a way to straighten my old pulley?
Thanks
Gerry

[David L.]

Re: 57 Water Pump pulley depth

Gerry,

Is the part number 3713974 as shown in the 1957 Chevrolet Parts Catalog? According to my notes I have (or once had) 3 "stepped" single groove pulleys (GM # 3713974) in my collection. The part number is NOT stamped on the pulley. According to my research done in the 1980's the total width of the pulley is about 2 27/32" +/- or about 2.84"+/- and the diameter is about 7 1/8".

The replacement pulley as of October 1968 is GM # 3827846. This is also "stepped" but has an additional reinforcing piece. I have (or once had) 2 of these pulleys, one stamped "3827846" and one not stamped.

Enclosed are photos of my research.

Dave

[Gary C.]

Re: 57 Water Pump pulley depth

David, nice research. You should write an article for the Restorer about your research and information. Am sure other members would appreciate it. I know Vinnie always appreciates receiving articles for the Restorer. Gary....

[David L.]

Re: 57 Water Pump pulley depth

Gary,

I've thought about writing a few articles in the past about parts that I have researched but I think this technical discussion forum is a quicker and much easier way to give and get information about parts. I have a B.S. degree in Civil Engineering, not English, but I did take a required course in Technical Writing about 42 years ago. I probably have had as many as 100 or more Chevrolet & Corvette pulleys but over the years but I have sold a lot of them.

I assume your spare pulley is GM # 3713974. Did GM have a problem with the 3713974 pulley and that is why they replaced it 11 years later with the very similar "reinforced" 3827848 pulley?

BTW, I don't think I know Vinnie unless it's the Vinnie from Charleston, SC.

Dave

[Gerry P.]

Re: 57 Water Pump pulley depth

Dave - thanks for the measurements and pictures. My spare pulley (which I bought a while back off ebay and listed as a 56-58 corvette fuelie and 409 Impala) looks like the it is correct for my 245 hp. It doesn't have a part number on it so must be a 3713974. Since the pulley on my car has a wobble to it, maybe that's the reason the service replacement has the reinforcement to beef it up a bit.

Gerry

[David L.]

Re: 57 Water Pump pulley depth

Gerry,

It might be a good idea to add the reinforcing piece (GM # 3720616) but it might throw off you pulley alignment by 0.060" depending on how the hub is pressed on to the pump shaft assuming you have a rebuild pump.

The parts catalog had a note after the part number. "Pumps having fan and pulley pressed to .348 dim. must use this reinforcement when replacing pump with pressed dim. of .288."

Dave

[Gerry P.]

Re: 57 Water Pump pulley depth

Dave, I looked at the parts book and the asterisk noting the need for the reinforcement appears to me to be related to 6cyl fan. When I get the old fan off, I'll do a measurement and go from there as to whether I need the spacer. It is also possible there is already a spacer already installed.
Gerry

[David L.]

Re: 57 Water Pump pulley depth

Gerry,

I remember back in 1965 right after I graduated from high school I bought a 1959 Chevrolet Biscayne with a 6 cyl. engine w/ M.T. Shortly thereafter the W/P pulley literally broke right where it was bolted on to the water pump. There was a junk yard not far from where I broke down and luckily I had my too box. Before the end of the summer the car had a 283 and a Hurst Mystery Shifter.

Dave