engine backfire and popping in the headers

[neilbyrd]

Just for "grins"....
Park the Jeep in a DARK garage and with hood up spray the ing wires with a VERY soapy water AFTER the eng. is running and warmed up and look for blue arcs of light.
Go back to OEM stock Champion spark plugs and set the gap at .045".
Respectfully,
LG

I tried stock plugs with .045 gap before and it ran bad on the street. Then again the plugs were getting black and wet then(it was before I rejetted).
The plug wires are brand wew and they dont even shock me when I touch them so I dont thing the will shoot sparks but I will try (the soap that is).

[Lumpy Grits]

Go back to the OEM plugs and see what happens, you got nut'n to lose and they may give you some type of base line.
Respectfully,
LG

[Jeeperator]

WELL.......MSD does.

Thats funny! Why does every msd coil I have ever bought come with a resistor??? If your using a msd6al system I am pretty sure the resistors built into the box. IIRC msd instruction also say they only require ~9volts. Sure it will run fine with 12 volts until that coil gets too hot. Neil since you installed the coil what do the instructions say? Do you have a constant 12volts going straight to the coil with out a resistor?. I am pretty sure .045 plug gap is way to big for a points style ignition. Btw what is the gap on the points or did you check it with a dwell meter?

[Lumpy Grits]

You do not use any resistor with the MSD "red" bx.
The resistor that comes with that coil is for use IF you don't have one already in use. You do not use two resistors........
ALL Jeep CJ-7's came with a resistor wire in the OEM loom for the coil in "run" mode.
Yes dwell would be a good thing to know and when did you last change the condenser
Cheers,
LG

[Jeeperator]

First off LG you need to reread what I and neil wrote. I have installed multiple MSD ignitions in many applications and I never said you have to use a resistor with a red msd box. I said its "probably built into the box". I never said to "install two resistors" I just said you need "ONE" wether its in the factory loom or not. Neil clearly says he wired the ignition and there is "NO RESISTOR". Well with most points "YOU NEED A RESISTOR" not 2 but 1. Neil is the wire loom out of a cj-7 If so I dont recall you saying it was. Neil I have a msd resistor somewhere around here if you want it its yours. Either pick it up or pm me your address and i will drop it in the mail.

[Lumpy Grits]

Neil, best of luck with your fix.
Respectfully,
LG

[aw12345]

Anybody thought of actually measuring voltage at the coil when it's running? Also no squabling kids. To get it hot run it balls to the wall in first gear should heat it up quick otherwise block part of the radiator, just to see if it will just mishehave when it gets over 210 degrees. I like to narrow problems down to the point where I can recreate them at will

[neilbyrd]

Go back to the OEM plugs and see what happens, you got nut'n to lose and they may give you some type of base line.
Respectfully,
LG

I had the oem plugs in there yesterday it was poppimg with them.

[Jeeperator]

No hard feelings maybe he just misread. LG definatly hit on alot of good points and its obvious he also has the experience to figure it out. Its just abit harder to diagnose when the vehicle is not sitting in front of you or you cant drive it around. I do know with points type ignition there should be some sort of resistor on the positive side of the coil. I remember a buddy of mine burnt his coil up in his boat because he forgot the ballast resistor. I also know after this is figured out throw those points in the trash and get a pertronix replacment magnetic pickup.

[neilbyrd]

I will try to answer all the question.

1.The gap on the points is .019 and I dont have a dwell meter to check

2.I have the coil ran off a switched 12 volt source

3.I last changed the condenser when I changed everything else within the last 2 months

4.I rewired the entire Jeep from scratch with a generic harness I got off of ebay it did not have a resistor wire

5.I have tested the voltage while it is running and it was above 12 volts at the coil


I am thinking that it might be the lack of a resistor. I forgot all about the resistance caused by heat and it kind of fits with what has been going on. I drive up the hill with my foot in it pretty good, it runs bad I turn around runs bad down to the street, I put it in high range and keep driving trying to get home and it starts getting better with the cool air pushing across the coil. Kinda fits like a puzzle.

[neilbyrd]

Thanks for the offer Beau but I am going to order the timing tape and I might as well get the ballast resistor to from Summit. Does anyone know what rated resistor I need for the 302. The accel coil didn't come with any directions.

[neilbyrd]

I just wanted to thank all of you for you help so far I know its not easy to troubleshoot something you cant see or touch, but if you guys want your more than welcome to come over and fix it for me (joking and not).

[aw12345]

Why not just get a whole electronic ignition setup from a 302 Ford and be done with all the ignition trouble Their older electronic ignition system is pretty reliable. Also I do not care much for any aftermarket racer brown add on stuff a lot of it never lives up to the reliability of the original OEM parts.

[neilbyrd]

Why not just get a whole electronic ignition setup from a 302 Ford and be done with all the ignition trouble Their older electronic ignition system is pretty reliable. Also I do not care much for any aftermarket racer brown add on stuff a lot of it never lives up to the reliability of the original OEM parts.

I have a 318 mpi that is sitting in my ramcharger and I am thinking of pulling it getting a sm435 and running that. I just want to run this until I get everything ready for that. I need to build a gantry so I can get the motor in and out. Both vehicles are to big to use a cherrypicker.

[aw12345]

My cherry picker will get it out, it was originally made to get engines out of lifted 4x4 trucks.