Calling old

[Farmall MD]

You got me thinkin now old. I always thought that the rain cap bouncin up and down was just gravity. It just does it at idle, not at operating speeds. Since there is not enough exhaust pressure at idle, the gravity would force it down between fires since it's running slow.

What books are you talking about, I'd like to check more into this. I know there is some overlap in valves, but it shouldn't be enough to create any reverse flow. But now that I think about it, marine engines don't have any overlap for fear of drawing water in the engine, correct?
Doug N

 

[old]

The books I'm talking about are the ones that explain how an engine really works. Back years ago there was a lot of thing they did to get more HP out of engines because of the fact an engine runs on cycles of push and pull at both the intake and exhaust. Thats one reason why header help make more HP because they make it so the push and pull is less on the xahust and years ago they made longer intakes for 6 cylinder engine to do the same thning. Same thing with the high riase manifold on the V8s it all has to do with the push/pull of an engine. Years ago I had some book on hot rodding and they expalin it well but I have long since lost them. I think they where peterson but not 100% sure any more. Heres one thing you can try to see what I'm talking about. Dtart up a tractor engine with the air intake tube off and hold your hand about an inch from the carb. You should feel the push/pull if you do that. Its the same at the exhaust but its painful to hold your hand close enough to feel it there. LOL And yes the fast the engine RPM is the less you notice it because it becomes very fast
Hobby farm

 

[Anonymous-0]

Sometimes you can notice it at the air intake into the pre cleaner. I can on my Cat. At first I thought something was wrong. Dave