The Stovebolt Site Forums The Shop Area Engine Shop Engine has rap when not idle

I cant play the video due to me and my equally stupid dialup system here in the dead spot of Texas. I was wanting to hear it first, but from the description, of rapping (meaning ?popping?) Could it comming from the carb? If so I would tend to think that you would have an Exhaust valve that is not opening. And when the explosion goes off, it cant excape when the exhaust valve opens ('cause it wont open) so whats left of the explosion's burnt gas and sound will come out the only place it can, which would be the Intake valve (when it next opens), then through the intake manifold and finally out the carb/aircleaner as a "rap", "pop", or some similar noise, At idle it may not seem to be there, but with some revs it will be very noticible- especially if you could load it in gear. If this is the problem then find out why the exhaust valve wont open. Worn out exhaust cam lobe or lifter, exhaust valve rocker arm set too tight, etc. Wish I could have heard it-this post could then have had more worth. Just find out where the "rap" noise is coming from-maybe a big crack or hole in the exhaust manifold.

Maybe this is why it sat 15 years before you got there?