Posted by Chriscase [76.212.175.88] on Wednesday, December 09, 2009 at 09:23:06 :
In Reply to: Re: Cracked Exhaust Manifold posted by Allen in CT [24.177.10.191] on Tuesday, December 08, 2009 at 22:14:05 :
There is enough reversion that air can get sucked into the cylinder, causing it to run lean and burn the valve.
Of course, it would be harder to do on a flat head, with the 'no overlap' cam.