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MG MGB Technical - ... still lumpy

electrical problems sorted, she is on the road again. Reasonable tickover at 1000rpm - hesitant underway - stuttering . Plugs in cylinders 2 and 3 sooty - 1 and 4 clean. Plugs new in the Summer - good spark on all four.Finger of suspicion pointing at inlet manifold gasket. Anyone seen this before ?
Roger Walker

Spray the area with WD40 or equivalent with the engine running and see if the engine speed/note changes.
Peter
Peter Burgess Tuning

Peter - thanks - same train of thought.
Roger
PS: Your head (one of two) - both very succesful !
Roger Walker

"Finger of suspicion pointing at inlet manifold gasket"

Would have to be two leaks (not impossible), one at each end, the mixture being richened to try and compensate, which ends up too much for 2 and 3.
paulh4

The most common head gasket failure point is between cylinders 2 and 3. It won't always show up on a standard compression check (values may seem OK) but there may be gasses blowing from cylinder to cylinder under a load.

I had this problem with a Volvo B20 engine once and the mystery was solved once the head was off. The car had overheated briefly due to a broken fan belt with no water loss.
Glenn Mallory

Glenn
You are right - the headgasket is under suspicion too
Roger Walker

This thread was discussed between 14/02/2017 and 26/02/2017

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