Pulley/Overheating Question

I have a 283 with 7" pulley on water pump, and 6-3/4" pulley on crank. It overheats.
My other 283 has 6-1/4" pulley on pump with 7-1/4" on crank. It does not overheat. Both have new water pumps/thermostats with good radiators.

I am thinking that the big pulley on crank vs small pulley on pump means pump turns faster, so no overheating. Opposite of smaller crank pulley/larger pump pulley moves fluid slower, creating overheating.

I don't remember my 10 speed bike gear ratio days so well. Am I on the right track?

 

It would be easy to test. Just swap the pulleys from one engine to the other and see what happens.

 

You always want a smaller pulley on the water pump,,moves the water faster,I have been there,done that. HRP

 

The pump is turning too slow for one and because of that so is your fan.

 

There are so many other factors. How about a picture of both engine compartments.
I would like to see what you may be missing.

 

What possibly could be the so many other factors?

This is a simple fix,we all live and learn,,most of us have learned this from having experienced the wrong pulleys in past. HRP

 

do both engines have the same radiator? that could be a big difference in cooling. most likely the pulley ratio though

 

Yeah, both engines are out of the vehicles. I do plan to swap pulleys. The keeper gets small water pump pulley/larger crank pulley. The other 283 is for sale. I figure the larger pump pulley in combo with small crank pulley is bass-ackwards.

 

If you're racing, you wanna do this to the alternator but never to the water pump.

 

been there done that with the pulley's. does make a big difference

 

I agree with BJR that it's easy to just switch the pullys to test your theory. However there can be other issues that create this problem and they should be mentioned. This year I've been asked about four cars that were overheating. My first question was "Is it spitting water or steaming ?". If it isn't then it's not overheating , if negative the answer back was always" Well my guage sayes so!". Results, one bad guage, one bad dash ground, one bad "NEW" themostat, and one bad radiator cap. I always trust my laser heat gun to verify actual temps.

 

could still be the radiator....next time it gets hot...shut it off and feel the center of the radiator and see if its hot, warm or cold.

 

Interesting. If you are turning mega-revs, you would put a mondo big pulley on the alternator to slow it down? You'd use a pulley on the alternator that was larger than the crank pulley. Hadn't thought of that.

 

All else being equal changing pulley is the way to go, do it.

 

Well I wouldn'y necessarily call it a "mondo" pulley or even one that's bigger than the crank pulley, but rather one that is bigger than the stock alternator pulley.

 

Good tips, all. Thanks guys.