Engine cutting out at low revs and lumpy tickover

[southerly95]

Advice would be very welcome with this please Symptoms as as per heading -when ticking over when warm the engine is missing a beat enough to rock the car. Also on over run the engine is snatching and cuts out coming up to junctions. The car is pulling very well indeed otherwise. Car needs 2/3 attepmts to start from cold when started 1st time before.

Possible contributing factors: unleaded head installed two weeks ago along with new timing chain and camshaft (standard). Has also had new coil, plugs and rotor arm (has something like lumenition) and carb refurb kit - these were done before the head was replaced and shouldn't be a factor. Head has been torqued down for 2nd time and all gaps are correct.

With plugs out engine turns with almost no resistance and there are no high spots. Compression check tonight shows all 4 cylinders equal on 150 psi. I have advanced timing a bit.

Other factors: vacuum pipe is properly fitted now when it must have been leaking before (diaphragm on dizy seems ok). Emission control valve now fitted with CORRECT rocker cover filler plug.

It doesn't seem mechanical in origin and can't find anything else wrong. I guess a sticking valve would have shown up in the compression test? Thanks in anticipation, John

[bmcecosse]

Can only suggest you play about with the ignition timing - swing it back and forth to get best idle, then road test to check NO pinking. And of course - idle mixture setting. Could maybe be fuel level problem - has it been set up properly after the 'carb refurb' - and, is the carb piston free to rise easily and does it fall back with a 'clunk' ?

[DaveC]

Try putting the old coil back on. My old trav used to do that after I replaced the coil. The old one was dented and manky so I thought I'd replace it, but she started to misfire etc when hot. When I switched them back she ran OK so I took the new one back to the shop and found the I had been given the wrong one (a 9Volt).