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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by RarlyL8 View Post
Keith, headers can glow red at idle if there is a significant balance problem.


I am still learning but my first guess would be glowing headers at idle might be more of a timing issue with a bunch of retard.

That if it was that lean on a cylinder or two it would miss fire. If not at idle it would balk pretty good with any application of throttle when CIS goes more lean for a bit.

My guess is a low compression motor could run as much as 15 deg's advance at idle to achieve peak pressure at 14 ATDC and run a cool exhaust temp.

I think Porsche uses vac retard at idle on most the 930's so they run at almost right at TDC. This was done on purpose to heat up the exhaust for emissions. With this, the air fuel mix might still even be burning when the exhaust valve is opening.

I wonder.

Old 02-07-2010, 02:04 PM
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