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Author Topic:   Potiac 400 overheat question
Dirt Roller

Total posts: 8
posted August 18, 2005 07:49 PM  
At the end of feature enduro races (70-100 laps) Car temp is 240. TOO hot, at idle after race car cools pretty fast down to 180 or so. Chang the oil after evry race. So far i have replaced water pump,fan,radiator and have repaired fan shroud many times. Timing is 16 degreees advance. Is this too much initial timing? Or my next qustion is about the heater bypass. I ran a hose from the heater outlet of the water pump to the back of the pass side head. old hose went to the heater core than the head. Should i have just pluged both of those ports?? I am at a loss and i dont think the motor can take to much more of the high heat. Any thought or help would be greatly appreciated.

Dirt Full Roller

Total posts: 50
posted August 18, 2005 08:15 PM  
I have a friend that runs pontiacs and i think he had to plug some holes in the heads to get his to cool i will see if i can find out what he had to do.

Dirt Maniac

Total posts: 116
posted August 18, 2005 08:15 PM  
Initial timing isnt what you should be worried about...check your timing at racing speed.

The fan should be about half in and half out of the of the shoud. What kind of fan are you using? Is the replacement rad new or in good shape? Also are you getting ample airflow through the grill?

What do your plugs look like under racing conditions? Are they of the correct heat range?

Try blocking off the heater lines at the pump and head.

Dirt Roller

Total posts: 8
posted August 21, 2005 11:32 AM  
Thanks for the reply, The fan is a factory steel fan, As per rules must have stock steel fan. I am running with a fan clutch. Should i bolt the clutch staight to the fan?? The fan is half in and out of the shroud. Nice call on the radiator, LOL it is a used one but it was boiled out and pressure tested. airflow through the grill is not a problem.I am possibly leaning towards the heater bypass hose that i ran. I think maybe it is taking hot engine water and dumping it right back into the head.? Any other ideas would be great cause we cant keep overheating this motor or we will be building a new one this winter. thanks again.

Dirt Forum Champ
Total posts: 5390
posted August 21, 2005 09:26 PM  
if you have to run a clutch fan weld it up so it doesn't work . get a solid fan if you can not those stock flex junk also how big is the rad? i ran a pont 400 in my old cruiser we didn't have a temp gauge but it would get hot on us all the time and lose power twords the end of the race till one nite we got a hole in the rad durring hot laps borrowed a 4 core rad instead of the stock 2 core we had and never got hot again. we plugged those ports but i don't think thats your problem al,l that is doing is pumping cool water into your head. if you could get by with it get an old heater core and put a small fan on it and use that as a second radiator

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