NKA Clone Temp

General Thoughts/Ideas, clone is building too much heat on the track. Dynos good, but have to get the temp down, I'm thinking maybe too high on timing?
35 Degrees Timing
CL4 Cam
.038" Main, 2 Hole Emulsion Tube (Went bigger to try and control temp), Like to run a .036"
No O-Ring on Idle Air

Any thoughts/Expertise greatly appreciated.
 

alvin l nunley

Premium User
What's the difference between the 2 engines? Something must be causing the difference in temperature. Swap heads between the 2 engines. Does that help? What about compression ratio? What's the difference in timing between the 2 engines? Swap carburetors and see if that makes a difference. Is there a difference in timing between the 2 engines? Have you checked the head gaskets? Have you checked the carburetor gaskets? Have you checked the float level between the engines?

The point being; there must be some difference between the 2 engines, you need to find what that difference is!
 
Sounds like I'll test some more, I was a bit concerned to put it to use in a big main event. Was pressed for time and didn't get a chance to put a lot of track time on it.
 

Fast 34

Member
375-450 is ideal. Much more than that and for a sustained period and you're in head gasket failure territory. We had the same issue a few years ago and going from a 0.038 to 0.036 main jet fixed the issue. Was able to turn more overall RPM as well. Night and day difference.

However, if you're temps climb throughout the race and never really plateau, you may have too much bite in the tires.
 
375-450 is ideal. Much more than that and for a sustained period and you're in head gasket failure territory. We had the same issue a few years ago and going from a 0.038 to 0.036 main jet fixed the issue. Was able to turn more overall RPM as well. Night and day difference.

However, if you're temps climb throughout the race and never really plateau, you may have too much bite in the tires.
if you went from a 38 to a 36 jet and it ran cooler it is because it made less power and burned less fuel after the jet change. Leaning one out to cool it off is not the way to do it In my opinion. The extra RPM may have allowed the flywheel to move more air and cool it off some.
 
if you went from a 38 to a 36 jet and it ran cooler it is because it made less power and burned less fuel after the jet change. Leaning one out to cool it off is not the way to do it In my opinion. The extra RPM may have allowed the flywheel to move more air and cool it off some.
I always thought leaner = warmer in general as well. Race track was slick, so it was lugging a little, but still turning good at the end of the shoot.
 

Fast 34

Member
if you went from a 38 to a 36 jet and it ran cooler it is because it made less power and burned less fuel after the jet change. Leaning one out to cool it off is not the way to do it In my opinion. The extra RPM may have allowed the flywheel to move more air and cool it off some.
Being too rich can build heat similar to being too lean when the engine is being stressed. Over fueling is not very efficient and doesn't let the engine accelerate off of the corners like it wants to (lugging). Its caused by partial or incomplete burning of the mixture and causes cylinder pressures to rise. Its closely tied to timing. Not saying that's the issue here, but its something to keep in mind.
 
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