back fire

[benson1]

hi all just a Q ive fitted a replacement carb an now can only stop it back firing if i advance the distributer timing 5 degrees any solutions to this[frame][/frame]

[Neil MG]

Leaking exhaust manifold?

Also check the obvious like plug leads to correct plugs, plugs tight etc.

I assume you have tuned the carburettor after fitting?

[benson1]

hi ive tried to tune carb im just getting a rich feed it wont go down to a weaker feed plugs tight leads right all new gaskets manifold tight uneven running ive got burning eyes head ache monoxcide poisening me thinks[frame][/frame]

[Neil MG]

Let's go back to basics. Why did you change the carb?

I assume there were some symptoms that suggested a new carb was needed? SU carbs are pretty bullet proof and once set shouldn't need touching for years.

[bmcecosse]

Don't understand why advancing the timing would stop it backfiring.... But a back fire is caused by unburned fuel being carried into the exhaust where it then ignites! So - I suspect the carb is overflowing into the engine - more fuel than it can cope with on low throttle. Check the float valve - and - where did the carb come from ?? Is the float chamber standing vertical??

[simmitc]

Benson, are you using a standard keyboard? Do the shift and punctuation keys work? Using them would make your posts much easier to read

[bmcecosse]

His head is swimming with the 'monoxcide poisening'...........