MGB blowback into carb when hot

[sb-1]

My 1977 MGB has this fault,it appears to be blowing back into carb when hot,under load.

Any ideas guys please?


Cheers

Steve

[freddytin]

Valve clearances too tight on the inlet side ?

[Huntsman]

sb-1 said:

My 1977 MGB has this fault,it appears to be blowing back into carb when hot,under load.

Any ideas guys please?


Cheers

Steve

Coil ok? My MGB coil packed up with a few minutes of quite remarkable misfiring from both ends! Sounded like a spitfire running on 11 cylinders.

Are you running points and condensor? When were they last checked/gapped/replaced?

Clean contacts in dizzy cap?

plugs clean?

Stobe the timing?

[sb-1]

Cheers guys,

She is going in for MOT/service tomorrow so will get garage to sort it hopefully.


Steve

[sb-1]

Took the car out for a run this afternoon,it is now much worse,when hot.It was also very reluctant to start when hot,which it has never been before.
I suspect it may be the coil.

[aw51 121565]

Lean fuel mixture causing the engine to run hotter than it should - and as we still get 'winter fuel' (more volatile than the 'summer' stuff) from the pumps until mid-May the 'lean mixture' issues are exacerbated (not an issue with fuel injected cars where the fue is under pressure, but in a carb-equipped car the problem shows ).

Then there's the current hot weather that will make it worse...

If this checks out OK, the timing is mebbe out? I would suggest too advanced. Anyway, check for a spark when trying to start from hot, before condemning the coil .

[sb-1]

I am collecting the car this morning and garage tells me it was the condenser and points!

Nice cheap solution and in my experience it turns out to be electrical 99% of the time.

Steve