Maybe I'm looking at this backwards but don't you want a smaller waterpump pulley than the crank if you want it to go faster?
There it is... I knew I saw that same page some where.Here is what Chrysler says about pump speed
Maybe I'm looking at this backwards but don't you want a smaller waterpump pulley than the crank if you want it to go faster?
Maybe I'm looking at this backwards but don't you want a smaller waterpump pulley than the crank if you want it to go faster?
You have a 6.75 inch water pump pulley. To get to 20% overdriven, you’ll need a crank pulley that is 5.40 in diameter
I wish I had all the knowledge in your big toe.Thanks for catching that.
If crank is 6.75 you would need a smaller dia WP pulley to spin it faster.
Or a larger dia crank pulley.
I would leave the crank pulley alone as it should be sized for the other accessories and just make the WP pulley smaller in dia to achieve a faster fan and pump speed.
5.5 to 6 would do it.
IIRC my 273 2bbl is 6.75 Crank And 6 WP stock but don't quote me.
1967 fan - WP - pulley - section from FSM (what look like dots I think are "*" based on other pages)
View attachment 1715495141
WOW!!!!! That has the 273 2 and 4 barrel 4 speed stuff at 40% overdriven.
******Edit: that is also with A/C
That is A/C AND CAP combo.
Guess that combo could generate some heat.
Also note the WP impeller is smaller dia and there are fewer vaines and the fan has wider blades. My guess is that are spinning the fan faster with a wider blade moves a **** ton of air. The smaller impeller and fewer vaines seems like it would push less water so maybe that was their way of keeping water flow about the same but increasing airflow.???
I also found it interesting that the majority were underdriven by 5 percent.
Agreed... But 273 4v 10.5 to 1 compression and 235 hp, certainly produced more heat than the 180 hp 2v.My best guess is those were all relatively low performance engines and relatively small displacements
Does anyone sell an 8” crank pulley? I looked and couldn’t find anything.View attachment 1715494996 Here is what Chrysler says about pump speed. They want the water pump turning 20% faster than the crank for maximum cooling. I suggest you get as close to that as possible. I’m only 6% overdriven, but I’m working on getting it to 20%.
You have a 6.75 inch water pump pulley. To get to 20% overdriven, you’ll need a crank pulley that is 8.10 in diameter.
At 10% over you’ll need to be just over or at 7.45 inches.
I don’t run a shroud. Your fan is plenty close enough to the radiator you won’t need one if the pump is turning the correct speed.
Fixed my damn math. Sorry for the confusion.
Does anyone sell an 8” crank pulley? I looked and couldn’t find anything.
Someone said, "no fan shroud needed"?? Wow! I must be old and *** backwards!?
Thank you.I don’t think so. I had a problem finding pulleys to get to 6% over. I have a friend who is going to look into getting some pulleys CNC’d and if we can get it done for even close to reasonable money (Id be willing to pay a hundred bucks for just a smaller water pump pulley to get me to 20% over) I’m going to speed my stuff up. Even though I have zero issues now, I want as much flow as I can get, because I believe that is another way to to reduce localized hot spots. When the flow is moving, you have more turbulence and that is good.
When I had my engine on the run in stand, I didn’t have a thermostat in it. I had to put one in because I couldn’t get any heat in it. Anyway, I took the cap off while it was running and even at just 6% over, the coolant was moving. Faster than I had ever seen before.
The other problem to be aware of is pushing too much pressure thru the heater core. High rpms and an overdriven waterpump could be the death of an older heater core. They sell restrictors to limit the amount of pressure for high rpm applications. Replaces outlet to the heater on the pump.
I am lazy and who needs a heater in SE Texas! So I always just bypass the heater and that way it won't start leaking on me down the road somewhere!!! lol