Put a water pump (casting #3782608) on a 1959 283, the water pump pulley does not match up with the crank shaft pulley. The Water pump pulley sits about an inch too far out from the crank shaft pulley. Several Auto parts stores I have looked at all have this as the correct pump. The casting numbers for an original 59 283 water pump are 3736493. Is there really a difference between the two? Did Chevy make a Short water pump? If there is a diference, then why does zips show the 58-70s as using the same water pump?

 

First off, there should be a 1/8 inch spacer installed behind the harmonic balancer to bring that out. If you have that, AND the Generator pulley lines up, then it is possible your water pump shaft is off. To correct this, remove the rear cover on the pump and using a press (with the shaft and impeller properly supported) move the shaft to where you need it to be. A machine shop can do this for you if you mark the change needed for them. The pump you have IS Not correct, the 493 pump is, but it will still work if that is what you want to use. IMO get the correct pump, and don't fuss with it. Pilot Dan

 

Thanks for the info. I did not know about the spacer behind the harmonic balancer. It did not have one when I took it off to rebuild the engine. I am still confused as to why the 493s' are shorter than all other chevy water pumps. Several auto parts stores list the one I have as "correct". Also Zips list the same water pump for the 58-70.

Is the 493 available at auto parts stores or am I going to have to go on a hunt across the land to try to find one? This rebuild seems to be one problem after another. The last piece to putting this engine together was the pulleys. Nothing has been easy with this project.

 

The 493 pump does NOT have an outlet hole on the top as many replacements do. The 6208 pump came out for use with the 327 motors. Mix and match is never an exact science but with Chevy stuff, you can make most things work.

 

Is there a gap between the pump and the timing chain cover or is it pretty close? If there is gap of about a 3/4 inch you have a long pump instead of the correct short pump.

 

I know this sounds elementary, but are you sure that you have the correct pulley? There are a bunch of different waterpump, generator, and crank pulleys and you can not mix and match them. There are a bunch of different combinations that are out there for many different cars, you have to make sure that the pulleys are compatible. Post some pics of the crank and waterpump pulley and we can probably tell you whether they are correct, but they also should have part numbers stamped into them.
I might be wrong, but I do not believe that a long pump was even available on the 608 casting. It should be a direct replacement with the 493 casting except for the drilled boss in the top of the pump that has to be plugged.

The 1/8" spacer that goes behind the harmonic balancer is meant to compensate for the thickness of the the motor mount plate. The generator pulley is specific to the Corvette as well since it also compensates for the thickness of the plate as well and it is also a different diameter than other pulleys. The diameter of the pulley is very important to assure that the tachometer reads correctly.


Regards, John McGraw

 

FWIW, i ran an engine without the 1/8" spacer for over 30 years with no problems, winding it up to 7K on many many occasions,, never threw a belt or any other damage.

if you can put it in without too much trouble, then do it; if not, it's no big deal. the alternator/generator won't care about an 1/8" that far out.
Bill

 

My 493 measures 5-11/16 from block mount to fan mount

 

I second the "is it the right pulley?" I also second Bill's you can run for 20+ years with 1/8" misalignment. Now I just did shim all my pulleys this spring. If you don't want to pull the balancer they make pulley shims about 20 bucks.

I had cracks in my crank pulley from the bolt holes out to the adjacent holes on each side,every one of them, just like people have shown on here before.

 

That's why you DON'T want to use washers to shim a pulley; they concentrate the shear loads directly on the bolt holes, resulting in fatigue cracks.

 

I didn't have any shims, washers or anything behind my steel chevy pulley. On my new Al pulley I have large shims that cover the complete surface with the hole patterns punched in them.

I guess the fatigue is just from decades of use?

 

Figured it out. It was not the water pump or the 1/8 inch shim, which would not have made a lick of difference since the variation was almost ¾ of inch. It was as couple people had stated….. the pulley. The crankshaft pulley that I bought is for a 1958E. The 1959 pulley, the correct one, is different. I purchased it from a guy who rebuilds Corvettes and he even had it tagged as coming from a 59. He also insisted that it was the correct pulley when I called him back to see if he had the correct one. From what I have gathered from internet research is that the 1958L is the same as the 59, so maybe that is why he thought he gave me the right pulley.