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Author Topic:   heat problems
77k
Member
posted April 04, 2004 03:30 AM
if you run a hose between the heads at the rear of pontiac will it keep it from getting so hot.Was lead the A untill i hit 270.


racer17j
Member
posted April 04, 2004 01:04 PM
what do you have for a cooling system .what size rad ,fan, spacing shroud,carb jets,timing any vacume leaks i used to have troubles with my pont 400 but thats because i had a 2 core radaitor went to a 4 core and fixed it right up


77k
Member
posted April 05, 2004 12:08 AM
4-core rad/no leaks.Four blade steel fan.Good shoud.timing 32 degree, was at 36 but i backed it off a little. geared down tring to keep cool, only turning about 5600.new 22lb cap.new waterpump.1/2 washer last week,went to 3/4 this week.Ran carb with chevy 350,406,377, with no prombles.


dirtbuster
Member
posted April 05, 2004 08:22 AM
gearing down may have hurt some. If it starts pulling the engine harder and lugging it down it will make more heat. What pulley setup do you have, a reduction drive or 1:1?


chad01j
Member
posted April 05, 2004 01:03 PM
i run pontiac also. i have had good luck using a 7- blade fan from the junk yard, think it came off a ford. i dont see how a 4 blade fan can pull enough air. i also do not run a fan clutch.


dirtbuster
Member
posted April 05, 2004 01:45 PM
Think of it this way which pulls more air a solid disk or a 2 bladed propellor. As you increse the number of blades you are getting closer and closer to a solid disk, esecially at high rpms. How many airplanes do you see with more than 4 bladed propellors?

FYI: GM replacemnt fan #405442 is a good 4 blade steep pitched fan.

[This message has been edited by dirtbuster (edited April 05, 2004).]

77k
Member
posted April 05, 2004 11:27 PM
I am running stock pully's. I have ran the old 4 bladed fans for a long time with no trouble.


Ego Racing
Member
posted April 06, 2004 08:18 AM
The airplane prop idea dosent work! Old planes did have multiple blades. the reason they stopped is rotational weight not air movement. Air boat racers use 5 or 6 blade carbon fiber blades. Watch the blades when it is running. Factory fans are not ment to turn the RPM's a racecar engine runs at, I have seen factory and some "race" fans that flatten out at anything over 3500 RPM. When they are flat they are moving no air. Make sure the pulleys are the correct ones, I have also seen factory pulleys where the crank pulley was larger than the fan pulley.
If you cannot find a race pulley set for the engine or rules will not allow then, measure a set of racing pulleys and goto the junkyard and find something in the same ratio.


juliaferrell
Member
posted April 06, 2004 09:58 AM
The 4 and 5 blade plastic fans are the best out there......20 bucks, lite, and won't tear radiator when something goes wrong. Cool 10 times better than steel.

Thought I might help.

dirtbuster
Member
posted April 06, 2004 10:22 AM
We just picked up a new GM 4 blade fan and i would like to see this thing get flattened out. You can watch it as you rev the car it doesnt flex. I know there are some fans that will flex and are designed to flex but I dont see that happening with this one. I know airplanes have multiple propellors but you would rarely see one with more than 4 blades. And you are also talking several times larger in diameter so there is more spacing between blades as well. With a 17" fan and blades that are 3" wide it doesnt leave much room between blades.

All I know is I watched a guy in a hobby stock change from a 6 blade to this same 4 blade fan(that was the only change) and his temp dropped 15-20 degrees just by moving more air.

[This message has been edited by dirtbuster (edited April 06, 2004).]

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