Inliners International Forums General Discussion Engines Water pump pulley diameter 250 Chevy

Hi all,
I have had my engine running hot in the past.
My crank pulley is 6 3/4 od & my custom water pump pulley is roughly the same..6 3/4 od.
Do you think I am turning the water pump too slow?
What size pulley is stock & what do you people think on the size I should change to?
Thanks
Hank

I'd have to go dig some of mine out to see whats what. But what size thermo stat u running? and do you have a shroud around the fan blade

I have a 160 thermostat & I do have a fan shroud.
I just think I am turning the pump too slow.
Thanks
Hank

well i think both mine are the same size But like i said I will get them outand a few others that i have and will let you know.

Hank what I have on my motor is the same. I have a bin of other L6 pullys I know are of a smaller size. It is over a friends I'll check those out.

When he looked at pictures of my GMC a couple of weeks ago, Tom Langdon told me that i need a water pump pulley smaller than the drive pulley so that coolant will flow sufficiently through the block. At present my drive pulley and water pump pulley are the same size, so this inquiry is of some interest to me. i'd like to know what the differential between the two pulleys should be.

God's Peace to you.

d
Inliner #1450

Hank sorry it took me so long But the smallest water pump pulley i have is 5 3/8 one groove.

I checked my pulleys and my stock pulley is 7 1/8 and the SBC pulley (that I am using) is the same depth at 6 1/4 Perry