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Discussion Starter #1
Specs:
    • 2.0 Alfetta engine with Weber DCOE139s
    • 11.2mm cams, 280 degree timed at 102, 104.
    • Bosch Blue coil 0 221 119 027 primary resistance 3.6, secondary resistance 7.79k ohms
    • Bosch distributor vacuum advance


      • I suddenly experienced misfiring and spitting from my carb three days ago while driving. Initially there was also quite a bit of gas coming from the large hole above the carb throat on the left. I thought it could be that I suddenly ran too lean, so I turned the idle screws out. No dice, so I changed float level and travel higher, then back to spec. Checked needle functioning and neither were stuck. Then I cleaned the carbs and checked the fuel filter. Fueling seems good.
        My next thought was that the coil was going (ref Alfar7), so I took it off and resistance was measured as above. Seems right for Bosch blue.
        Next suspect was distributor which I swopped out. Now spitting from the carbs disappeared, but still a bad misfire if I try to take it above idle and power is down quite a bit! Changed the points and condenser as well. Advanced ignition timing and still the misfire persists.
        All spark plug leads have been checked.
        Idle is fine, carbs are synched, plugs are fine, but anything off-idle makes the engine shake, with bad misfiring. Swopping floats and jets hasn't helped.
        What should be the next place to look - can it be the rotor, coil to distributor lead or something else that would fail suddenly and make the engine misfire?
 

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Do a compression test to make sure that you don't have a burnt/stuck/broken valve. If an intake valve is stuck open or bad the engine can push compression out through the intake since the air has an outlet through the intake.

Paul
 

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Discussion Starter #4
Yes, one should always recheck the basics! My car fouls plugs considerably quickly - I think it's because I haven't driven her enthusiastically for a long time.
Problem solved with plug and lead swap - bought two new leads and 12 new plugs. I'm running BP6ES, which is hotter and more projected than I ran on the standard engine, but don't foul as easily as the B7ES.
At least I've learnt more about my car and refurbished and reset some old things.
 

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Measuring the winding resistance of the coil tells you very little when you are troubleshooting. Coils fail due to insulation breakdown. The best way to test it is to replace it with a known good one.
 
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