Reply To: Lister d sucking exhaust port

[trusty220]

It definitely sounds like a valve problem. The best way to check if the valve timing is correct is to bring the piston up to TDC (Top Dead Centre) between the Exhaust Stroke and the Induction Stroke. The valves should be “on the rock”, where the exhaust valve has just closed and the inlet valve is just about to open. If the valves are doing anything else then move the camshaft around a few teeth until you get this condition.

If they are “on the rock” at TDC then have a look at the valve seatings as the exhaust valve may not be sealing properly and allowing gases to leak past.