Head Gasket? Burnt Valves?

[peppiB]

Car has been running fine. Parked up after a run no problems. 4 days later went to take it out. It started fine but as soon as I asked for power the engine died.
It will start no problem. tick over no problem but as soon as I press accelerator the engine speeds up briefly then dies. I have a clear fuel filter so can see that is flowing OK and the points spark OK. These days I am in a wheelchair so I can't do a compression test til friend is next off, but is there anything else could be causing the problem (the old memory isn't what it used to be)

[bmcecosse]

Well - I doubt it is gasket or valves, assuming the idle is smooth and even?? Probably something very simple such as points/condenser/sticking carb piston - or most likely I would suggest - fuel feed problems. You don't need a filter - there is already one in the pump (which may benefit from cleaning) and a second filter can only add to fuel flow problems in hot weather.

[peppiB]

Many thanks for that. Car doesn't have the original SU fuel pump and the fuel chamber on carb is full. Will check carb piston (I can manage that unaided) and change the condenser

[AndrewSkinner]

Ive just had almost the exact same problem. Mine was the piston in the carb was sticking.

You would accelerate the piston would rise and then get stuck up. It would then flood the engine and die.

Again just like you started fine and idled fine. I guess the stalling/cranking wobbled the piston down again.

[peppiB]

Thanks Andrew

have had the dashpot off and cleaned the inside, and the needle and it made no difference. Started to change points and condenser but pain prevented me from finishing. I should have recovered enough in a couple of days to finish the job and hopefully crack the problem. Distributor is an accuspark 45D where the points and condenser are wired together in 1 unit. There is no post to hook the points onto so scratching head as to how exactly one is supposed to set them! Can find plenty of pictures of the whole unit but none with the cap off showing the inside

[bmcecosse]

email accuspark and ask them. If you post up where you are - maybe someone nearby will pop round and have a go at it for you.

[peppiB]

Fresh set of eyes on the problem and points set

Still no improvement though

Further investigation revealed the fuel pump was drawing in air. Hopefully that will be the cause of the problem. We will see

I am in Newcastle upon Tyne btw

[bmcecosse]

Well done - you should put your location in your profile.....keep it as vague or as accurate as you wish!

[peppiB]

A final update on this. Having tried everything else but car still not running correctly, I took the head off and ....... burnt out exhaust valves on pots 2 and 3. I had a spare head (here's one I made earlier) so fitted that and she fired up and runs fine

[lambrettalad]

well done

[bmcecosse]

Odd that it would be two - probably one let go and then when the second one went - it had insufficient power. A compression check early on would have shown the weakness. IO urge you to set exhaust valves gaps at 15 thou - inlets at 12 thou if you wish - AFTER you retorque (44 ft lbf) the head after the first heat cycle. Valves burn out when the gap closes up - either due to recession - or simply because they get too hot. And the ex valves on 2 and 3 are the hottest - since they share an exhaust port. Slightly larger gap helps to prevent this - and do check/reset initially after 1000 miles - and then again every 3000 miles.