Electrical issue in engine circuit

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Coils and condensers can have intermittent and heat related failures. I would start with them. A cracked cap, or one that is oily/dirty inside, can cause misfiring. Double check the point gap (preferably by dwell). Check the pivot bushing on the breaker plate. As the engine warms up the gap can change slightly and if the gap is on the edge of causing problems the heat related changes can be enough to push it over the edge.
 
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I checked the dwell with an engine analyzer. It was a solid 23.

Kcmash
 
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I have had a lot of good fortune. But none ought not overlook the persistence behind that good fortune. If did not just happen. Oh, the things I have learned when doggedly pursuing problems and solutions relentlessly.
There is an old saying in Spanish that says that "luck (or good fortune) was invented by those that did not want to work hard to achieve their goals". There was no good fortune or luck involved, it was just a TON of hard work and persistence.
 
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If you still have the resistance wire in the ignition circuit any conventional 1.5 ohm primary resistance coil will work. The NGK coil at NAPA is fine or the Pertronics Flamethrower I coil is fine also. I hope you get it sorted out easily. Chuck

Edit: single diaphragm, single points, 24-29 degrees dwell.
dual diaphragm, single points, 26-31 degrees dwell.
 
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71 conv,429cj, 4spd 3.5 N-case, it's not an original but the running gear is correct.

69 Fastback, it's a project. going to be a built BBF with a Lenco 5spd. Looking to get the car in the mid 8 to low 9 sec and still be streetable. I just hope I get it done before I am too old to drive it. lol.
Have you checked the voltage to the plus side of the coil? Check when cold and again when hot. The wiring is a resistance wire in the harness under the dashboard and it’s 50 years old. Your coil being just as old could be suspect as well.
Check your spark plugs, are they clean like new, or are they wet with fuel? This is your clue as to where to look.
 
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1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
Talked to a points/condenser guru yesterday. He said to be sure to go with a blue wire condenser versus a black wire. I had never heard of this, so I bought the Standard Ignition FD77. It was amazing how much larger, heavier, and more robust it appeared than the black wire condenser. I also picked up a Standard Ignition Blue Streak coil, since I think my coil may be part of the issue.

Have not installed the coil or fired it up yet, but I hope I am on the right track here.

kcmash
 
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Well, the coil and condensor have resolved my backfire problem. So that one is past me.
I have crappy power assist right now on the brakes. I also have the power fluctuation when trying to maintain any speed. Acceleration, is fine with no bogging, but any attempt to hold a steady speed has fluctuations in the power. (I plan to try 65 Jets in the primaries versus the stock 63 Jets)

Anyone know what vacuum I should be seeing at Idle on this thing? 351C, 4V quench heads, Boss 351 cam grind on a roller cam. Not sure if I have a bad brake booster or if I have a vacuum leak.

Advice/suggestions are appreciated.
kcmash
 
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Well, the coil and condensor have resolved my backfire problem. So that one is past me.
I have crappy power assist right now on the brakes. I also have the power fluctuation when trying to maintain any speed. Acceleration, is fine with no bogging, but any attempt to hold a steady speed has fluctuations in the power. (I plan to try 65 Jets in the primaries versus the stock 63 Jets)

Anyone know what vacuum I should be seeing at Idle on this thing? 351C, 4V quench heads, Boss 351 cam grind on a roller cam. Not sure if I have a bad brake booster or if I have a vacuum leak.

Advice/suggestions are appreciated.
kcmash
KCMASH, sorry you are going through so many issues now but I am following this thread closely. After going through my brakes and purging all of the air in the bleeding process, after the car is running, my new power brakes seem to go a lot lower and have less firmness to them as well. Good luck and hopefully you figure this one out.

Tom
 
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