underdriving water pump

[freak]

The previous owner of my A installed a smaller than stock pulley on the crank which presumably was put there to underdrive the water pump/fan and extend it's life. This is ok with me except that this removes the hand crank cam so I can no longer use it. Does anyone have any opinions about underdriving the pump and whether or not it is a help? I don't have the original pulley but should I get one and put it back on?

[eagle]

As long as the belt is not overtightened the water pump will last just fine. Maybe the owner was scared of "pushing too much water"... Uh Oh, here comes that subject again. Maybe the point of the smaller pulley was to keep the water pump from cavitating?

[BRENT in 10-uh-C]

The Yapp pulley IMO really is not of a benefit for a stock-type, street driven engine. The water pump with a stock-sized lower pulley will not push any more water than your correctly functioning stock radiator can handle ...even at 60-65 mph range. The bigger detriment as I see it is the charging system. The slower speed makes a generator less efficient and an alternator takes much higher speeds to energize. Whether the hassle of changing out the pulley at this point is up to you but if I were in your shoes, I would find the first reasonable opportunity to exchange it out for an original size unit.

[TDO]

I would change back to the original pulley, And if pushing to much water is the problem ,than grind down the impeller. Or you can buy one that's already ground down. Most suppliers have them.

[Purdy Swoft]

My opinion is that the smaller crankshaft pulley would only be of small benefit in racing applications. The faster the water pump turns, the more water out the overflow and the more horsepower consumed. The faster the fan turns, the more horsepower consumed. I would think that grinding the tips off the impeller vanes and shortening and rebalanceing the fan blades would give a similiar benefit while keeping more coolant in the system.

[Timberbeast]

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I don't want to hijack this thread but could someone please post a picture of an impeller that is turned down and a stock impeller. I think seeing how it should be done would be helpful.
Thanks

[Brian T]

Hello Jerry,
Here is the link to Snyders showing the 2 impellers, I tried all of the tricks to stop throwing out water including this one , but inevitably ending up buying a new radiator, wishing you much luck.
Brian T.

http://www.snydersantiqueauto.com/1938

[Brendan]

why not put in a thermostat or put a freeze plug in the water neck and drill a 5/8 hole in it. I put a thermostat in my A and it slows down the water. also I did the freeze plug trick in my 36 21 stud motor and that worked good two

[PC/SR]

I put in a Stipe undersized pulley just because I did not much trust the fan turning that fast on hillclimbs, and a few extra horses as another benefit. It works fine. Also used the stock crank nut to hold it in so the crank works too. Check and see if the prior owner changed the nut or something and if the stock crank nut will fit. It should.