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?
Is this a fair radiator?
- Thread starter Tad
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There it is... I knew I saw that same page some where.
That page helps resolve a ton of misinformation
yellow rose
Overnight Sensation
yellow rose
Overnight Sensation
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.
Update, I tried to get some measurements crank seems to be about 6. 25, WP I can't get a good measurement
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I wish I had all the knowledge in your big toe.
yellow rose
Overnight Sensation
I went back and corrected my wording so it’s now right.
You are right at 10% overdriven with what you have and that’s pretty good.
I don’t have a service manual for years where a 273 was available, but the principle is the same no matter what year you have.
1967 fan - WP - pulley - section from FSM (what look like dots I think are "*" based on other pages)
yellow rose
Overnight Sensation
WOW!!!!! That has the 273 2 and 4 barrel 4 speed stuff at 40% overdriven.
******Edit: that is also with A/C.
That’s why Chrysler stuff didn’t overheat back in the day when the GM and Ford stuff did.
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.
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I forget the Champion 3 core radiator part number I used, but I think it was CC526. It cools my 68 416 Barracuda really well. I used a 16" single electric fan.
yellow rose
Overnight Sensation
It is interesting. My best guess is those were all relatively low performance engines and relatively small displacements, so overdriving them wasn’t needed. And to speed the pump and fan up does cause more parasitic loss.
Agreed... But 273 4v 10.5 to 1 compression and 235 hp, certainly produced more heat than the 180 hp 2v.
Does anyone sell an 8” crank pulley? I looked and couldn’t find anything.
Look for a smaller dia WP pulley, just watch the ID
Don't know if they would be correct
[FOR SALE] - More Misc. Virus Sale
Don't know if they would be correct
[FOR SALE] - More Misc. Virus Sale
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yellow rose
Overnight Sensation
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.
Someone said, "no fan shroud needed"?? Wow! I must be old and *** backwards!?
yellow rose
Overnight Sensation
I said that. If the fan is within an inch and a half or so, you don’t need it. Some of the aftermarket shrouds are straight junk. The OE’s used them because the fan was too far from the radiator to be effective at idle and low speed.
I can’t remember where I read it, may have been an ASE paper or maybe it was some engineering testing, but a friend let me read this paper and it was about how a fan shroud can cause the air to stack up at the radiator when the road speed was high enough, the RPM was high enough and the shape of the shroud.
IIRC a short, blunt shroud was about useless. It would stack air up very quickly. It never really changed the coolant temp but, it did act like a giant air dam because the air can’t get past the fan and the shroud.
That’s why I get the fan as close to the radiator as I can and skip the shroud. The only real issue without one is getting caught in the fan. I need to fabricate something around the top of the fan for that, but no shroud for me if I can avoid it.
Thank you.
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.
yellow rose
Overnight Sensation
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
yellow rose
Overnight Sensation
LOL I live in a high desert valley and it gets pretty hot here, but the winters are COLD and I drive my junk year around. Otherwise I would have blocked mine off too!!!
The one I used is on page 756.
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