Posted by Brian in Oregon on Friday, September 28, 2001 at 2:21AM :
In Reply to: Re: Cracked exhaust manifold. posted by casebro on Wednesday, September 26, 2001 at 10:22PM :
...this is why you should never fire up an engine without the exhaust manifolds installed. You'd have to jet up several sizes to compensate.
You can also burn exhaust valves merely by unrestricting the exhaust. Example, you have a restrictive single exhaust on your V-8. You cheerfully install headers and a larger diameter dual exhaust. You blissfully drive it for a few thousand miles, until you find a burned exhaust valve(s) because you forgot that a less restrictive exhaust leans out the mixture by scavenging the cylinder more efficiently. The greater the difference between a restrictive and a free flowing exhaust, the more you must jet up the mixture.
BTW, WWII fighters like the Spitfire and Mustang and bombers like the British Lancaster had very short exhaust stacks. Short stacks are the most free flowing exhaust systems of all with almost no backpressure. They got away with it because the mixture was richer to compensate. This also caused unburned fuel to light off outside of the exhaust stack, which is why nightfighters often used flame dampners.
|
Follow Ups:
This board is powered by the Mr. Fong Device from Cyberarmy.com |