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Old 01-26-2020, 09:54 PM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 10,702

Originally Posted by Scott Hersha View Post
...It seems that a slug of fuel still residing in the aft portion of the tilted (taildragger) manifold, including the 18? of hard line upstream of the original valve placement, might be enough residual fuel to trigger a POP in the opposite cylinder in a lost spark EI setup.
Scott, consider the waste spark, arriving at the top of the exhaust stroke, or a little before. Both valves are open, thus it's not possible to generate significant cylinder pressure. Even if a combustible mixture is ignited, absent pressure there can be no kickback. Kickback has a single cause, ignition inside the closed cylinder too far before TDC.

The risk to having a lot of fuel or water or chicken soup in the plenum is hydraulic lock...sucking a big slug of incompressible liquid up the pipe and into the combustion chamber. Which is why, way back in post #16, I said I would be henceforth recommending a sniffle for most installations.

Originally Posted by vic syracuse View Post
As much as I respect you, Dan, I wouldn't really consider one shutdown as a reliable indicator. Perhaps after 100 shutdowns?
I respect you too, so tell me, what do you think might happen during one of those hundred shutdowns with a purge valve?
Dan Horton
Barrett IO-390
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