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Author Topic:   Engine Overheating-----please help
posted September 30, 2001 10:41 AM
Lose the electric fan first off.

Then go to the basics...

1 - Be sure you are not running too much timing, and the motor is jetted correctly.

2 - Be sure the radiator is not plugged full of mud. Use a hose and rinse thru from the backside until the water coming thru is clear. Add this to your maintenance schedule too.

3 - Be sure the cap is the highest point in the cooling system. If it is not you need to be able to bleed the air out at the highest point. You can get a radiator petcock and mount it in the thermostat housing. Or several companies offer really nice purge tanks that mount to the thermostat area (I sell stuff for Art's Radiator).

4 - Slow down the water pump, if you have A/c pulleys they are spinning the pump way too fast.

5 - Never run without a thermostat or restrictor. If you do water flows to fast and cannot transfer heat properly. Also a restrictor helps build pressure in the system and water under pressure has a higher boiling point.

6 - Make sure the water is circulating thru the rad by removing the cap while the system is cold and start engine.

7 - Check your hoses, and be sure you have a spring or reinforcement in the lower hose. A soft or older lower hose can suck shut at higher rpm and restrict the flow.

8 - Insure that about 1/3 of the fans blades are outside the fan shroud. The fan cannot be completely inside or outside the shroud or it will cavitate the air and not move it through the radiator.

9 - try a chemical solution, either water wetter (about $7-10) or a case of **** for you and the crew while you sit inthe pits and it cools off.

There are many other things you can do, some free some not so free. Check your basics then shout if none of this helps.

posted September 30, 2001 04:45 PM
About five years ago I also had over heating problems and an old timer at the track gave me some good advise. Chevy came out with a really poor design. If you look at the rear of the heads there is a water jacket that goes no where, so when the system gains pressure the water is pumped back there and goes no place. To fix the problem drill and tap an 1/8" pipe thread in the rear of the intake manifold on both sides where the water jacket lines up. Also drill and tap an 1/8" pipe tread in your water neck or thermostat housing. Then in the back of the manifold ***** in 1/8" pipe fittings on both sides, and one 1/8" 3-way tee in the water neck. the old timer who told me about this said it was very important not to go bigger than 3/8" dia. hose and run it from each side in the rear of the manifold to the tee in the water neck and it knocked 15 degrees right off the top. And I have done this on every motor I have built since then. It has always worked for me. Good luck.

posted September 30, 2001 09:26 PM
Some people do say, not to run a restrictor.
I agree with layne, run one. That component is in the cooling circuit for a reason. Your going to have more problems with the temp being too high as a result of the fluid not being in the radiator long enough to transfer the heat, than the fluid being in the block too long. If your willing to give the restrictor a chance and take the time, you can experiment with the diameter and tune the cooling system to suit you needs. Give it a shot.

posted October 01, 2001 12:07 PM
the restrictor acts to slow the water so the heat can exchange from the block to the water and the water to the radiator to the air. I have never had success running without one, with the thermostat removed the water flows too fast to be efficient.

posted October 01, 2001 06:55 PM
Not that it matters much, but wheels....the engine is a 289/302 bored to 40 over.

Hey guys.... as wheels mentioned we are very new to this racing thing. I purchased a Jet Modified on July 16th of this year. The engine was built to be used with alcohol but we are running in a gas class. Some people are telling us that it is bored to much for gas. The walls are too thin. Whats your opinion?

posted October 02, 2001 10:58 AM
wheels, we like to run at least 8 laps at speed (that would be 2 minutes or better on a straitaway) then shut off the engine AND push in the clutch (immediately)before slowing down. I just coast to an open spot in the pits . Without a track to run on it's kind of tough to check your mixture/fuel distribution unless you have access to a chassis dyno & exhaust analyzer(which is really a great way to go).

On the topic of restrictors, while trying to avoid offending anybody, this voodoo is considered by most in the cooling industry to be just that. For those whose radiator cap is on the "high pressure" (input)side of the radiator (do they even make radiators like that anymore?) a restrictor might be in order.
For those truly interested in the cutting edge in cooling technology read Chris Paulen's (of C&R Racing) article in the Nov issue of Speedway Illistrated or log on to:

Good Luck

posted October 03, 2001 07:44 PM
Dirt-Tracker---Thanks for correcting me bud I Stand corrected--lol

C21-- thanks much for the input bud. We will check into this a litle deeper to see if we can get this clean shutoff worked out. Sure wish we had one more race--hehe Thanks agian bud

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