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Author Topic:   overheating
Dirt Newbie

Total posts: 4
posted July 30, 2002 07:56 PM
i have an over heating problem i've tried every trick in the book.We are out of ideas need some help.

Dirt Full Roller

Total posts: 36
posted July 30, 2002 11:42 PM
Are you on gas or alky?
What size motor?
What compression?

* Shroud
* No restictor in the thermostat housing
* Holes in the front nose piece
* If a 400 block, pulling water from the middle cylinders
* Full size radiator
* Good water pump
* Springs taken out of hoses
* Solid steel fan
* Fan about 1-2 inches from radiator
* Running anti-freeze (I know its illegal but it works)
* Fatten motor (jetting)
* check timing


Dirt Newbie

Total posts: 4
posted July 31, 2002 07:05 PM
i'm running a 383 on gas. i have a shroud on and the fan is about 1 1/2 inches from the radaitor.I have a new radiator with holes in the nose piece.We set are timing at 34 to free up the engine{something else we tried this week}.stock water pump but its new and it has good springs in the hoses.and we have a 5/8 restricter in the bottom car will be at 250 by lap 13 or so,sooner if we have a yellow.we even went as far as putting an electric fan on the out side of the radiator to pull air threw it.didn't help at all.we have are cam 4 degrees advanced could that be part of it?i'm running a 750 holley with 75's getting plenty of fuel i think. when i load it and from the shop to the trailer its at 140.

Dirt Full Roller

Total posts: 64
posted July 31, 2002 10:32 PM
Why would you take the springs outta the hoses? Would'nt that cause them to collapse? Maybe I'm missing something here.

Dirt Full Roller

Total posts: 36
posted August 01, 2002 01:20 AM
If you have hoses that don't kink then you can take the springs out. The springs can slow down the water flow. I know there are different theory's on water flow. Some think you need to slow it down to let the water stay in the radiator longer so it cools...WRONG. Let the water flow and flow quickly. Get rid of restictors and thermastats. I have tried it both ways and mine now runs much cooler with high flow.


How far does your fan stick out of the shroud? Half of the fan should be inside the shroud and the other half outside. If the fan is too far in, it will suck ZERO air. I know you probebly already know this but alky will solve all your problems. A alky conversion might be expensive but a DNF from a front position or a blown motor is more...

Dirt Maniac

Total posts: 183
posted August 01, 2002 08:01 AM
You need a spring in the bottom hose! that is what keeps it from getting sucked shut. The 5/8" restrictor goes in the top hose. tis slows the water speed down.

Dirt Full Roller

Total posts: 36
posted August 01, 2002 02:08 PM
Well Gene, I must have those "good hoses". If you have problems with them collapsing, try a hose clamp or two around the outside of the hose...

Like I said before, there are those who believe that you must try to slow the water. All I can say is try it. Take out the restictor and see what happens. You can thank me later.

Dirt Newbie

Total posts: 4
posted August 01, 2002 03:20 PM
i have the fan half out of the shroud.As far as restricters go i have tried it both ways,no restcticter restricter in the top hose,resricter in the bottom hose and one in both.after i come in and get it cooled down we take the cap of and i have to ad water radiator is bran new and i know it don't leak.

Dirt Roller

Total posts: 24
posted August 01, 2002 03:50 PM
If you read the tech tips at the following url:

Stewart is the ultimate authority on cooling. NO RESTRICTOR IN T-stat Housing, NO REDUCTION PULLEYS, QUALITY WATER PUMP THAT WILL NOT CAVITATE AT HIGH SPEED and a good fan and shroud are the answers. If you run alky you can get by with 1/3 the capacity of cooling. You can't be short of cooling on a gasser. Done that battle!

Good Luck

Dirt Roller

Total posts: 14
posted August 01, 2002 09:25 PM
Sounds to me that you hit the nail on the head. I think cavitation is the problem. Stock pumps have a stamped impeller that was not designed for 6500 rpm. 150 bucks for a good water pump should help a ton. Good call 19

Dirt Forum Racer

Total posts: 80
posted August 02, 2002 02:32 AM
what kinda of water pump do u have?
i have heard thier is a certain kinda that flow backwords and thats not good...
try alky...that helps like no other
it will do your trick.

Dirt Roller

Total posts: 24
posted August 02, 2002 03:45 PM
Have someone with experience read your plugs, I run 83 and 86 jets with the power valve functional. You may be fine due to different carb characteristics, but it sounds a bit lean. Also make sure the cap is in excellent shape (it should be a racing 28lb cap). The cap can sometimes see extreme pressure at sustained RPM even before overheating takes place. This could be why you appear to loose coolant. Stick your overflow hose in a bottle to see how much coolant you are puking during each event. My engine is a 14:1 430 on gas. I have had similar problems but I have no problem
cooling since following the tips on the
Stewart page.

Dirt Full Roller

Total posts: 40
posted August 02, 2002 08:00 PM
DS, I also run gas. I have ran a 383, 406, and 358 now. I have never had a hot motor. No fan shroud, no holes in the nose. I use a Stewart water pump, about 6 years old with no trouble, 3/4" restricter in thermo housing, the good green stripe hoses with internal springs. I think one of the most important things is the fan. I only use the old 4 blade Ford type fan about 1" to 1 1/2" from the rad. I also always run 2 bottles of Red Line water wetter. This combo has never ran over 200 deg in summer on gas.

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