Point gap affect on timing

Reading over the thread I think you can rule out timing for now. Being the plugs are carbon fouled(black) and not oil fouled (oily black) I would be more likely to look at the fuel mixture/internal carb leakage. A too rich condition can allow unspent gases to leave the combustion chamber and ignite in the hot exhaust manifold and/or the exhaust system on decel. Might be worth going through the carb at this point. I assume your vacuum gauge at idle is steady and not pulsing.
 
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I have had some success with my distributor problem. Observe the taper on the offset cam connect. I replaced with another that was rectangular and am now getting a reasonable vacuum 22. A short drive is encouraging. Once I get insurance on I will give it a highway run.
Let you know.
 
retep said:
Still playing around with solving this problem.
I once again tightened down manifold and carb (vac leak)
Cleaned and gaped plugs. Would appear to be running rich (black carbon)
Checked to make sure coil polarity correct using voltmeter
Replaced fuel pump

Could condenser be an issue? I have Dennis Carpenter coil adapter with condenser supplied.

Carb is my next consideration.
Again thanks for any input.
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Did you bypass the ignition resistor under the dash ?
 
I am going along with 51 Merc on this...it may just be too lean a mixture. I had this pbm with an old VW and after changing the carb setting the pbm was solved. No more back firing on deceleration. Terry
 
Just a thought: Could it be as simple as wrong plug wire to wrong cylinder? All the indications match this theory..

Christian
 
Sorry I failed to mention I have returned to original coil and condensor (tested) and resistor is connected.
Carb is 97 and I will be looking at it further as it still seems to be leaking from plunger at times.
Vacuum is steady.
It's raining here today. Probably won't get on the highway until tomorrow.
 
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