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I posted this in the 60s forum as well but here goes.
I have a 300-punched .020, stock CR, comp 252 bump stick, stock 1bbl intake and exhaust, points dizzy W ignitor, true 12V coil.
The problom is I have a random miss occuring on all cylinders at varrious times. Not all dead at once or in sequence just randomly. sometimes 1 cyl sometimes 2. Sometimes it will spin for a minuite or more with nothing and other times it occurs non stop. All speeds and loads.
What I have done.
Re set timing 5 times. Changed plugs, tightened intake and exhaust, Tested for vaccum leaks with ether 3 times. Disconected all vaccum accesories at manifold, tightened carb, tightened all valve rockers slightly, Used timing light on all 6 holes to verify randomness of miss. It misses at the coil or earlier as it will stop the light on the coil lead. The coil is not hot.
Is my ignitor burnt? I would think that it would not run if that were the case. I intend to install points to test that tomorrow. I aint an idiot but this dragon is giving me a hell of a chase.
Assuming from where you said you posted originaly, you have a point style distributor. Check the shaft for movement from side to side. Could be bouncing the points. Only the tinyest of movement is allowed. You could go to the parts house and check a new/reman unit out to get a comparison.OBCB
While the air gap on the ignitor module isn't real critical, I could see where a worn distributor shaft could cause your problem. Especially since it seemingly affects all cylinders.
Is the dwell OK? If not check for wear in the dist./cam gears and the timing gears. Recheck the connections clean and tighten them all. Try spraying water from a squirt bottle around the ignition system and see if it gets worse. I think I have heard of someone using WD-40 like the water but checking to see if it gets better. Someone please correct me if this is not OK to do. I have never tried it. If all is good... swap the coil with a known good one. Does the coil have oil in it?
I will try gapping the plugs to 45 tomorow harte3.
I have had it in there for nearly two years so I dout it but maby it will help.
Today I........ Ohm tested the coil, wires. all were good. The coil wire was slightly high so I bought and changed the wires. No change was noticed.
Pulled the ignitor out and threw points in. Miss was softened, but was still there.
Tomorrow I will gap to .045. I am at .038 now but will try the larger gap.
If no change I think it is time for a compression test. Might be a burnt valve.
Burnt valve isn't going to make the miss move from cyl to cyl. Has to be common to all. Reason I say check voltage to coil for intermittent readings is it's possible your coil feed wire could have a bad place in it, loose connector, clean back to ignition switch.
Voltage was good. I agree with you on the burnt valve thing. When I wake up in the morning I am going to......
Gap plugs to .045
Take carb off and make sure there are no tears in the mounting gaskets.
Pray to god, allah, yawah, budda, shiva, the kwanza guy and preform a rain-dance.
I hope this works as we are supposed to get slammed with a three day blizzard starting tomorrow, and I am three peoples storm ride to work.
I was going to regap my old plugs at .045 and found my old gap to be .042. Also while gapping I found one plug to be cracked from the top of the insulator to the base of the electrode. I thik I found my original miss.
Then when I installed my other set of old plugs, (I am a little cheep you know.) at .038 I caused a miss due to excessive voltage and insuffecent gap.
I am going to spend the $10 and get a set of new 45's.