Gents, I just ordered a new water pump for my ‘61 261 that I will need to press into a short shaft pump for clearance.
Does anyone know the correct measurement that I need to press it to? I want to confirm my old one is correct and press the new one before removing the current one.
You might want to check on one thing. There were pumps made by different people and in different ways. About 15 years ago a friend tried this only to discover the long pump's shaft on the one he bought was shouldered...meaning you could only press the mounting flange down so far and it bottomed. We figured it was to make assembly faster and less prone to error. Just a suggestion. Some of them were not shouldered.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Moving the flange back solves one problem and creates two others. The fan blades will hit the balancer unless you run a very small diameter fan, and the fan will be off center on the radiator. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Moving the flange back solves one problem and creates two others. The fan blades will hit the balancer unless you run a very small diameter fan, and the fan will be off center on the radiator. Jerry
All too true! I ended up using a spacer on the pump flange and a non stock fan with minimal blade pitch. I only overheated twice in fifteen years and 80 k miles or so. Both incidents were on long very warm summer trips of 400+ and 300+ miles where traffic was stopped dead. I ended up turning the heater on full with the heater fan on high. I suffered greatly but thankfully traffic moved and the truck and I were somewhat back to normal.
~ Cosmo 1949 Chevy Half Ton Rocinante, like Don Quixote, he is awkward, past his prime, and engaged in a task beyond his capacities. "...my good horse Rocinante, mine eternal and inseparable companion in all my journeys and courses." ...Don Quixote, Cervantes "If you come to a fork in the road, take it."...Yogi Berra "Rudeness is the weak man's imitation of strength." ...Eric Hoffer
I wouldn’t think the “face” of the pulley would be that much thicker. I bought mine already pressed as well, but it seems slightly longer. I think 4” will be a better pulley alignment.
How far you press the flange is entirely dependent on which pulley you use. I have used a factory V8 pulley that has a shorter offset than the factory 6-cylinder pulley. That makes room for a 6-blade truck fan that you can remove without removing the radiator first. You'll find that if you use a 16-inch fan, you'll have to drop the radiator several inches for the fan to clear the lower hose connection.
Later, I added AC and rather than trying to drive the fan, alternator and AC compressor off the one water pump/fan pulley, I got a 2-shiv crank pulley and used a V8 2-shiv water pump pulley for an air-conditioned V8 with short shaft water pump. Whichever V8 pulley you use, you will have to press the flange an additional 1.1 inches onto the pump shaft. Don't use my figures but measure it yourself for your application. The distance that matters is from the block mounting surface to the pump's pulley mounting surface. That dimension has to make the shivs on the crank and water pump line up exactly.
If you are using an after-market short shaft pulley then its offset will determine how far to press. You get one chance to get it right because it's really hard to press it back out with a regular shop press (at least with my 20-ton) and a puller won't move it in my experience. If you go too far you'll have to shim it back out.
1951 3800 1-ton "Earning its keep from the get-go" In the DITY Gallery 1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.
