Thread: 6cly backfire

I normally associate backfires with bad / incorrect timing settings and /or associated compotents - ie rotor arm, distributor etc.,

Or if the heads need a de-coke - do we still do that - apparently the carbon build up continues to glow and causes pre-ignition - does it run on after switching off ?

Start with the ignition as Ladas said is most likely.

When we were younger a friend's mum's car was backfiring badly and they had their usual mobile mechanic out to look at it, who diagnosed it as definitely a valve problem on number 3 [say that with a Rainman voice], big quote, mum was worried, all the rest. Of course after I convinced her to let me have a quick look over, basically just wanted points tidied.
Point is, start simple... and wary who you pay for work.

Most likely ignition, air leak into intake manifold (carbie or manifold loose or vacuum line off/leaking), possible carburetter problems. (in that order)

But with this engine I would suspect exhaust valve problems and check tappet clearances and run a compression test to rule this out, as continued use with a leaking exhaust valve will get very expensive.

John