MQ Petrol missfiring/hunting

[CJ Burns Esq]

A mate has just had an engine rebuild in his MQ petrol. Had 1mm oversize pistons fitted and head decked etc. All valves have been sorted. All vacuum hoses checked for leaks using a can of carby clean sprayed over the hoses (makes the engine run funny if sucked in).
Problem is the engine hunts (Engine RPM rises and falls).
Does anyone have any clues/hints/tips? Any information would be greatly appreciated.
CJ

[matthewK]

could be getting to much or not enough fuel?

maybe not enough charge going through the sparks?

check ya sparks, leads, points anythink else im missing?



matthew

[r0ck_m0nkey]

What condition is the carby in? Mine was in poor condition and was doing all kinds of magical things until i ripped it off and threw it across the yard and replaced it.

[90swbGQ]

I had a fungas growing in my tank & in the carbie also. The mechanic found it & blew it out when he did a tune. Has been ok till recently when it started missing again.

I thought it might have been water in the fuel system & was throwing in a cup full of metho every now & then but no good, changing fuel filter etc & even drained the tank.

The way it was acting I really thought it was electrical. Na, was this fungas in the fuel.

[Screwy]

Doing that can only be an electrical problem or a fuel problem.
The motor is fine.
Dont think vacuum is the issue, besides your can almost always hear vacuum leak in those L28's.
Check points and condensor etc. Maybe the carbi is ready for a rebiuld

screwy

[CJ Burns Esq]

I'm going back to give the guy a hand on Wed so I'll check up on the carby situation. Me thinks a carby kit wentr through it but it could also be a worn butterfly
We have had the dissy apart and installed a new Vacuum advance and pulled apart and cleaned and greased the advance plate it as well. The only thing I didn't check was the slop in the dissy drive which may be a part of it as well.
See what happens on Wed.
CJ