Over heating issues with my Briggs

[alvin l nunley]

Running at about 450°, with a 52 jet, and no tape.
Kart is not tight, not leaking fuel
Don't want a bigger jet, as the air is dense at this time of year.
Is this a spark plug issue?
Thoughts in how to get my temp. down?
Thanks

When the air is dense (which I doubt, because warm air "tends" to be less dense) you need more fuel, not less. I don't know what kind of engine you're running, or what carb, or what fuel, but it doesn't matter, when the air is dense, more air is pushed into the engine, and you need to compensate with more fuel. Without an air density gauge, you're just guessing anyway. Don't take this wrong, I'm not putting you down, I'm just trying to help. One other thing, if you go from a .052" jet, to a .053" jet, that's a 3.86% increase in fuel.

 

[FinishLine]

When the air is dense (which I doubt, because warm air "tends" to be less dense) you need more fuel, not less. I don't know what kind of engine you're running, or what carb, or what fuel, but it doesn't matter, when the air is dense, more air is pushed into the engine, and you need to compensate with more fuel. Without an air density gauge, you're just guessing anyway. Don't take this wrong, I'm not putting you down, I'm just trying to help. One other thing, if you go from a .052" jet, to a .053" jet, that's a 3.86% increase in fuel.

Thanks so much for your reply, and clarification of the air density, which I had backwards lol.

 

[FinishLine]

as noted make sure your coil vane is in. what size track and how hard are you turning the engine.. I usually turned my stock heavy engines around 6900 on 1/5 to 1/4 mile tracks. smaller I might turn it a bit harder..

I probably as in the minority but my dyno tests always showed more power around 375 on head temps. I almost never got over 400 degrees and ran a 48-50 jet all year long. these were with I/C engines and the Bu8H plug.. timing was generally a static 29 degrees other than a few engines which liked a lot less.

I'm turning about 7000 RPM. Actually not sure on the size of the track, but I can get around it in about 11 seconds, give or take a few tenths.

 

[CarlsonMotorsports]

From what everyone is telling me, 450° is not sustainable over a period of time, as it well wear out the motor quicker. Furthermore, I'm told the proper range is 410°. to 425° for these flatheads to make the most power.
Can I get a confirmation on this?

One big difference is how much time is on the engine and the clearances that were set when it was machined.
The ex valve/guide will most certainly stick on a fresh engine that runs 450*, while that same engine with 6 or 8 races on it will be just fine at 450* for a lap or two.
Now, if the guide is already loose (ie not replaced or not kept to tighter tolerances,) then it might well be fine at 450* fresh.

Same with your piston and cylinder.
An fresh engine set with .002" cylinder clc. will not like 450* much at all. In fact it won't like much more than 350.*
One set with .0045" clc. will like 450* better than 350.*

Steel bore engines always like more heat than aluminum (cool) bores.
If you've got an aftermarket hardened steel sleeve, it can take even more abuse before it causes problems.

Always consult with your engine builder as far as temperatures that he prefers.


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?Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
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