pulley alignment

[Ray G.]

My friend has a very original 65 coupe with the 365 hp engine. The water pump pulley is back about 1/4 to 3/8 of an inch from lining up with the harmonic balancer pulley. What can he do, just shim it up? Tks

[John H.]

Re: pulley alignment

My friend has a very original 65 coupe with the 365 hp engine. The water pump pulley is back about 1/4 to 3/8 of an inch from lining up with the harmonic balancer pulley. What can he do, just shim it up? Tks

First thing I'd do is to verify that it has the correct pulleys - lots of weird things happen to 44-year-old cars.

[Joe L.]

Re: pulley alignment

My friend has a very original 65 coupe with the 365 hp engine. The water pump pulley is back about 1/4 to 3/8 of an inch from lining up with the harmonic balancer pulley. What can he do, just shim it up? Tks

Ray-----


The first thing to do is as John suggests: check that the pullies are correct.

If they are correct, understand that there were 2 different waterpumps originally used. There was a 1/8" difference in hub spacing between the two. The most common pump (and the only one available today either new or rebuilt) is the one with the 1/4" hub spacing. I believe the 365 hp application used the one with the 3/8" hub spacing. So, if the mis-alignment is actually only 1/8", this may be the problem. If so, I do not recommend trying to adjust the hub on the pump; just use spacers to correct the problem.

Some Corvette applications also originally used a spacer between the hub and the pulley. This spacer was GM #3720616. My recollection is that it's about 3/16" thick. It's still available from GM.

[Doug F.]

Re: pulley alignment

Ray,

Over the years i"ve found a lot of rebuilt water pumps with the hubs pressed on too far or not far enough, the fix is not that hard, but it's not for the faint of heart, require taking the pump off and pulling the back cover off and supporting the impeller then pressing it to the correct height,

We have done a bunch of them over the years and always measure them prior to installation, about 1 in 10 needs to be tweaked.

The spacer Joe speaks of, i believe is more of a reinforcement and can be found between the pulley and the fan on some early models, it's not a good idea to try to shim between the pump and the pulley from a balance/wobble stand point.

[Wayne M.]

Re: pulley alignment

This table might help [for Chev engines up to 1965] (distance from where pump bolts to block, to flange front where matching clutch fan slips on).

Also, his waterpump pulley should look like this (on my L76 air car). Part # 3848904 stamped on one side; diameter 6_9/32". The AIM calls for 3850979, but the Chev parts catalog Rev 1st July '65 calls for the part # first quoted, both for '64 & '65 for the C60/L76 combo.

[Ray G.]

Re: pulley alignment

Thanks to all foe your help! We took Dougs advice and adjusted the impeller. Problem fixed! Again thanks to all, once again the NCRS comes to the reescue. Ray