Need C2 L72 Pulley Help

[Steve Miller #39713]

I have a 1966 coupe with a non original 427 that I am trying to have appear as original as possible on the outside. The only option that matters for this discussion is power steering (N40). I have set up the belt pulley arrangement as noted on page F159 of the AIM with the alternator being driven off the power steering pump. Since the car has not been on the road for almost 20 years, let alone with this engine, we have been checking things out and noticed that the alternator was generating insufficient voltage at low RPM's and bearly enough at 2000 RPM's.

We switched to a smaller pulley on the alternator and the result was about 14.5 volts at an engine speed over 1000 RPM's. That seems fine now. I took the car for a short cruise and noticed I needed a lot of effort in the steering. My thought is that maybe that pulley is also too big. So now I am wondering if all the pulley's are wrong.

I got the part numbers for the alternator and power steering pump pulleys out of the AIM but, was wondering if anyone can give me dimension information on the factory pulleys. Also, similar information would be helpful for the crankshaft and water pump pulleys as well.

Your help is always appreciated.

Steve Miller

[Joe L.]

Re: Need C2 L72 Pulley Help

Steve-----

As far as the power steering pump pulley goes, only one was ever used for 1965 to 1974 Corvette big blocks. It's a 2 groove cast iron pulley of GM #3878245, which is 6-1/2" OD.

The alternator pulley for your application was a piece of GM #3871242. This pulley is a machined steel pulley with an OD of 3-5/8".

The crankshaft pulley should be a 2 groove cast iron pulley of GM #3863108. This pulley is 6-3/4" OD.

The waterpump pulley was a 2 groove pulley of GM #3864480 (later, GM #3906656). It is 7-3/16" OD.

[Steve Miller #39713]

Thanks Joe

Thanks Joe. I will be off to the body shop next week and see what's what.