I believe I know what’s causing the “after-burn” ( to hot in combustion chamber) don’t know how to stop it.
I checked timing, I believe right on, its at second mark on T cover, installed correct heat NGK plugs (BPR5ES-7734)
sprayed carb cleaner around base of carb looking for vac leak. No jump in RPM’s.
the only major thing I removed ALL smog equipment. So now I have no EGR but that’s an emissions thing.
Any ideas would be a huge help in the right direction.
thanks
Not sure about "after burn", I thought they fitted after burners to jet engines
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If you are describing what I would call "running on" where you switch the engine off and it carries on running very lumpy for a few seconds, then may be check for the air leaks/weak mixture direction, possibly after the "de smogging", it can also be caused by local hot spots in the combustion chamber or an engine needing the cylinder head off for a "de coke" get rid of the carbon deposits etc. An engine running too hot will also aggravate the problem.
As a youngster I had a beaten up old 1964 MGB Roadster with over a hundred thousand miles on it, I bought it for £90 and flogged it mercilessly and used to boast I could get out and lock it up whilst it was still "running on" after a hard run! Nowadays it would be a valuable classic worth thousands like most of my old cars I sold too early or ex wife aquired in divorce.
Another thought is "pinking or knocking" often heard when labouring up a steep hill in too high a gear, this can be caused by over advanced ignition timing or being timed for 5* high octane fuel which it was designed for but no longer available.
Two things also to check is the accuracy of the ignition timing marks, as a rough guide starting point 7.5 degrees before TDC static timing and then adjust further or less to compensate for current fuel quality. If in doubt I have taken no1 spark plug out and gradually turned the engine to find TDC and compare it withe the marks on the pulley, even using a protractor as a basic guide from where I found TDC to the advance marks. Often I would check a static timing position and then run the engine with a strobe timing light at different engine speeds to make sure it doesn't over advance.
The second thing is to make sure the automatic advance and retard mechanism in the distributor is not worn or broken springs causing excessive timing advance.
Regarding spark plugs, after a run take the plugs out, keep them in the same order to compare any differences between cylinders ( an air leak on one port of the inlet manifold would show on just one plug possibly) and then compare with an NGK or similar manufacturers chart for engine faults on plugs. The other thing to try is a colder running plug, not quite a "racing" plug , generally the further the center electrode insulation protrudes into the combustion chamber the hotter it runs so making things worse.
