4100 again, update.

GreenAcre · Sep 30, 2018

Well I got the tire aired up and got it off the stump, and got it back... Played with the new air filter and even took the air filter hose off, and cranked over the pump to advance the timing. The thing runs perfect unless it's at higher rpms. Then it smokes and sounds ragged. I'm out of good guesses. Could weak or broken valve springs let it float the valves at higher rpms?

Bern · Sep 30, 2018

Valves don't float on a diesel engine - this isn't some 8000 RPM gasser you're working on.

If this thing was in my shop, I'd put my diesel timing light on it to verify the operation of the automatic advance unit. Lacking that, you'll either have to keep advancing it, or else live with it.

Have you tried it under a load? A high RPM misfire tends to go away when the engine is under a load.

Fordfarmer · Sep 30, 2018

Bought a 5200 once that the auctioneer described as having "a miss at high rpm". I thought it missed all teh time, but was more noticeable at higher rpm. Turned out to be a couple bent pushrods. Moved teh rocker arm, but not enough... and at higher rpm, the miss was worse.

4100 again, update.

GreenAcre

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Bern

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Fordfarmer

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