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MGB 1800 wont idle smoothly

Jik

Freshman Member
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I've upgraded my Magnette 1500 engine for an MGB 5 bearing 1800. (Refurbed by a reputable machine shop)
All the ancillaries, manifold and H4 carbs literally unbolted and transferred across.
It's great at speed, starts well, but engine wobbles at idle, whereas the 1500 3 bearing was super smooth.
It's an occasional splashy misfire sound from the tailpipe on idle, it's certainly not smooth. Doesn't smell rich.
Engine mounts new. Ignition good. Timing at 10 deg. Plugs light brown..carbs balanced.

All I can think is the carb needles (HB) are making it run weak at idle. (Tried richening the jets, but no change.)

I've checked for air leaks of course.

Any suggestions welcome of course..

Thanks
 
Does it have a lumpy camshaft?
 
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