Pulleys what really works best..

I have a set of Factory single groove pulleys work very well but i am considering changing to a smaller crank pulley and a new water pump pulley the new ones would be Aluminum would this change make my car run cooler or hotter and is it worth it..

Yes its a 440 motor

largest crank pulley (might be 7.25") this will give you the fastest alt speed (always needed) and run the smallest pump pulley, just add an anticav plate to stave off cavitation (needed with the faster vane speed) & this will put your pulley ratios spot on

Crank pulley to water pump pulley ratio (crank pulley diameter/pump pulley diameter = ratio) should be about 1.33:1 for a street car.

We run March under drives on 2 BBs and a SB.None run over 180 or so even in the 90s.No charging problems either.My kids BB runs the OE 62 alt with a new style reg to replace the points one.All run stock rads.My rad is all OE from 65 and never been touched.Rocky

I was wondering my buddy has a 572 Stroker hemi and it never gets hot and he runs the small crank pulley and large water pump one..

If the engine is hot rodded a bit both idle speed and redline will be higher than stock. A smaller crank pulley can get accessory speeds back to normal. I run the 6.25" March pulley in place of the 7.25" stock on my "warmed up" BB and figure accessory speeds are pretty close to stock with the higher RPM engine. If you go too far with the smaller pulley and really slow down the accessories, you could get into cooling and charging problems. In my case the 6.25" pulley works great for charging and cooling but each application is different.

Be advised my crank pulley was different( on my stock 67 440) than any other newer pulley. the measurement from flat surface, that mounts to the crank damper, to the belt groove was 1/8" inch different..
My crank pulley was bad ( too rusted to reuse) and I was in a scramble trying to find another.. I was VERY lucky that Randy ( 1wildRT) knew what I was talking about and had one he sent me..

Darn I miss him... Anyways you have been warned...

Many years ago I owned a 71 Corvette, which I still own. It had come equipped with all options including AC, but with the base 350 engine.

At one time I decided to build a destroked 400 small block with an LT 1 forge crank and LT 1 solid lifter cam. Immediately proceeded to blow off the AC belt at 6,000 plus RPM.

Found the reason that Corvette never offered AC with the LT1 engine,,,that is until 1972.

When drag racing I would remove the AC belt because when it blew off it would take out the PS and alternator belts with it.

One day replace all pulley's with March pulleys,,,smaller crank pulley, same size water pump and alt. Problem solved.

Interesting side note how GM solved for 1972 Vette, the only year they offered AC on LT 1 engine. They merely lowered redline on tach from 6,500 to 5,600 RPM on 72 models,,,numbers are correct best I can remember,,,still same solid lifter camshaft and same other specs except for no lead premium compression lowering on 71 and 72 models.

Still own car today.