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Discussion Starter #1
I read about guys putting headers on their engines and running into problems with excessive under-hood temperatures

and so the dumb questions is

why are under-hood temperatures higher with headers that with a manifold

One would think that if the headers moved the hot exhaust gases out fasterf there would be less heat radiating off the exhaust system

I guess you can tell that I am not a hot-rodder
 

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1977 Power Wagon Utiline
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First off there are NO stupid questions only stupid answers. Secondly the underhood heat issue is usually due to the headers not sealing completely to the gaskets or coming loose. Its one of those things you have to pay close attention to.
 

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acton mike said:
I read about guys putting headers on their engines and running into problems with excessive under-hood temperatures

and so the dumb questions is

why are under-hood temperatures higher with headers that with a manifold

One would think that if the headers moved the hot exhaust gases out fasterf there would be less heat radiating off the exhaust system
Not a dumb question at all. You are right about the headers radiating less heat. That is in part due to the decreased mass of a header vs cast iron manifolds.

I believe the "excessive under-hood temperature" thing is a misunderstanding of the problem. Headers often sit closer to the starter area of most vehicles. That proximity of heat to the starter tends to make the starter (actually the relay/solenoid) to go bad. Several easy mods can eliminate those issues - a sheild between the header and starter or an exhaust wrap are a couple.

Also, the tuning of the carb to accomodate the improved breathing exhaust will help with heat issues.

L
 

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Mopar Madness - Get it...
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I believe the "excessive under-hood temperature" thing is a misunderstanding of the problem. Headers often sit closer to the starter area of most vehicles. That proximity of heat to the starter tends to make the starter (actually the relay/solenoid) to go bad. Several easy mods can eliminate those issues - a shield between the header and starter or an exhaust wrap are a couple.

Yup, L5 is talking about what I've run into on a few occasions. In fact, exactly.. It's not really the overall 'under the hood' temp, but the fact that the headers (BB or SB) pretty much 'incase' themselves around the whole starter. There ain't a whole lot of room on that side (And I've found this to be true on truck chassis, "A" bodies and "B" bodies) and the tubing just has to go where it's gotta go... Usually very close to the starter.

Back in 'The Day' I used to just get a sheet of asbestos gasket material, and wrap the starter with it. Always worked pretty good. Of course you can't buy that anymore, but I'm sure someone, somewhere makes shields/wrap for our applications.
 
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