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Discussion Starter · #1 ·
Just put my new Edelbrock performer heads and Comp cam (and lifters) in. Put a new Edelbrock water pump on to...new thermostat, flushed radiator, new cap, new hoses. Brought RPM's to 2000 to break in the new cam. Within five minutes my engine was very hot and my gauge was almost pegged out. The top radiator hose did have pressure in it. What could it be???? I was thinking faulty edelbrock water pump? but would I still have pressure in top hose? What could make it heat up that fast? Timing or Richness could not do it that fast could it?
Thanks for all the help....
trying to get my everyday driver running again!
 

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I dont know what it would be. But, I had the same thing hapen to me. I replaced the radiator, hoses, water pump, and thermostat on my cleveland before break in. After about 10 minutes mine did the same thing. It was overheating like mad! I think it may have been the timing. What type of fan are you running? Im currently using a flex fan but I will soon be replacing that with electric
 

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Discussion Starter · #3 ·
i am running an elecric fan...never had any problem with it before.....
what did you finally do different to make yours stop overheating? I only cranked it once.....It fired right up and ran good....just got hot really fast!
 

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Discussion Starter · #5 ·
It is part number 8843 for 70-78 302's. I have a 70 mustang. it should not be reverse rotation. If the pulley spins...shouldnt the water pump impeller spin too? How do you know if it is flowing in the right direction....it should be though!
 

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Were you by chance doing this in a garage, or any other area without good airflow? When I broke my truck engine in, I had to keep a hose with a slight trickle goin over the radiator to keep the temps down. Just not enough air to keep it cool. Never had a problem after that, just during break in.
 

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boss302....

Sounds like air in the system!!?? The pump is centrifical and will not pump air....if air bubble reaches it no water will move resulting in a hot engine.

Also check thermostat. Is it in the right way?? Also, drill a small "bleed hole" in the thermostat flange and position it up so as to let air bleed through it while filling the engine. This will help prevent an "air lock"!!

Good Luck,
Cobrajack
 

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After eliminating possible problems with the cooling system, use a shop fan to blow air through the radiator. This should help your temp while breaking in the cam.
 

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Discussion Starter · #12 ·
I filled my radiator before I started....but after i finished, the water level was the same......shouldnt it have went down?
 

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I have two areas to look.

When I started my last 351w up it would get really hot FAST. Fought this for a while, took out t-stat(brand new I might add and tested it w/ boiling water and thermometer, didn't open), put in new t-stat problem solved.

Last week a buddy dropped in his new 351w in place of old 5.0, got real hot, real quick like yours. I told him check jetting and timing. Carb was jetted for 5.0 (#62's,way to small!!) Jetted up to 78's, adjusted timing and the motor is a lot happier.
 
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