[mopar56]

hi guys, my sons truck has a slight miss under load we have tried to track down for some time now, all the basics are done compression, spark, etc, we have narrowed it down to either the coil or distributer, before he purchased the truck some one had installed an after market accell coil, (big square yellow one), the suspicious part is there is two ballest resisters on this truck, it is a 1980 318 auto, the stock one is in front of the driver on the firewall and then there is a second one mounted beside the coil, it has three wire going to the coil, one from one side of the ballest resistor and the other two go into the taped wire harness along the firewall then the other wire from the ballest resister goes to the factory wire harness along the intake, is there a possiblity the second ballest resistor is causing havoc?, thanks

 

[dana44]

The ballast resistors simply prevent higher voltage from one place to another, reducing it to the electronic ignition which runs on 9.7v instead of 12v, so that one is OK. On the other side, wires going into a wiring harness doesn't give any indication of where they terminate or go to, so the wiring needs to be tracked down. I don't think it it can really do any harm reducing the voltage, but you could get a wiring diagram and rewire the coil properly, the Accel super coils are pretty good units.

 

[mopar56]

ok thanks, I am going to check the wireing against the manual, I suspect that the origanal ballast resistor wires go over the coil then the other resistor was added and the wire in the harness by the intake goes to the auto choke?, I will ohmn these out some time this week and get back, also has anyone had any issues with the stock distributor pick ups?, I cant think of one I have ever chnaged. this truck has new plugs, we did this three times over two years, new wires, cap, rotor, new mopar performance ignition box, the carb was changed a while ago as the throttle shaft was a bit worn, (thgis one is two but not much and I find it highly unlikely that the same problem would be there), it has aluminium intake no egr etc, this thing is pretty simple not much left?

 

[dana44]

A high speed miss can be a ton of things, but check for powder in the distributor around the parts, it can cause high speed spark jump (or shorting), to which it could also be the carb, and being a 1980, with all the sensors in the intake manifold, there would be a flow interference thing going on. If it is the manifold I believe it is, look at all the pipe plugs in the runners, the angles of some of the doglegs in it, and if you can understand anything about flow, picture where there may be hiccups through the runners and that may be your answer.

 

[mopar56]

thanks, just to clarify on your last comment, this has a edlebrock performer intake, just a temp sensor and vacuum tree and all the lines off it look good, just a brake booster line and vacuum advance as the air cleaner door line is disconnected at the time, so last night I stripped back some of the wire harness to see what was going on, one of the existing wires from the origanal ballest resistor now goes to the bottom of the new ballest resistor instead of the coil like it origanally did then a new short wire off the top of the new ballest resistor goes to the positive side of the coil, this wire is red or maybe pink, on the negitive side of the coil there is a black and yellow wire which according to my manual should go to the control module on the dash and exiting the engine harness on that side there is the same color wire going into the brain box or module, lastly there is a blue wire, ( i think aftermarket ) comming off the neg side of the coil going to the tach in the truck, the other side of the origanal ballest resistor seems correct with one wire going to the start relay and the other,(two wire on one pin) spawns off to many other positive things such as fues box etc, so it seems I could eliminate the second ballest resistor quite easily just by connecting the origanal wire from the origanal ballest resistor direct to the positive terminal on the coil and disconnecting the second wire on the second ballest resistor, at the same time I thought I might try a different coil suitable for use with external resistor, my only thought was dose anyone know if the excell super coil requires a second ballest resistor in line and thats why it is there? I cant think of why, also I have looked in the distributor and see nothing unusual, thanks again for all the help.

 

[dana44]

From the sounds of it, the original ballast resistor was one of the double plug ones and this is how they rewired it. You can remove the second resistor without a problem, get a wiring diagram and wire it properly. I have used several of the Accel coils and no, it doesn't need to have a ballast resistor at all. As far as the miss goes, can you give a more specific time it happens, or under what conditions it happens?

 

[mountainrich]

I've had problems w/ ballast resistors occasionally. You may not even need them if you upgrade the ignition; but, I have never used the Mopar ignition box.

 

[Bob Lincoln]

Is the reluctor gap on the distributor pickup set to .006" with a brass feeler gauge? Does the gap stay consistent as the distributor shaft is rotated?

http://books.google.com/books?id=rtkDAAAAMBAJ&pg=PA38&lpg=PA38&dq=reluctor+gap+pickup&source=bl&ots=MZ8O6qJeeX&sig=bC3kbM-TwzBEYSicmGpDzx9pfhI&hl=en&sa=X&ei=3OdhUOqiM6zK0AHdyIHIBw&ved=0CD4Q6AEwAg#v=onepage&q=reluctor%20gap%20pickup&f=false

 

[mopar56]

thanks again, I do have a wireing diagram and I am going to go back to origanal spec, I will check the .006 gap as I do have a brass feeler gauge, both ballest resistors are the two prong style but the origanal one has two wires coming from one stud, according to the manual this is correct, as far as the miss goes it is always under acceleration, it could be mild acceleration as you are suttley climbing a hill or full out acceleration from a stop it feels like a bad plug there is no back fireing just a miss like it is not hitting on one cly, all plugs have an even burn and last time I checked compression it was all around 145-150 lbs if I remember correctly, thanks again

 

[mopar56]

well I eliminated the second ballest resistor and swapped out the accell with a stock coil, went for a short drive and the missed seemed to be gone, came back from the road test and swapped out the coil back to the accell but left out the second balllest resistor, truck ran fine at idle but didnt road test then it ran out of insurance and as many upgrades are planned for the winter we are not sure when we are going to re-insure it so it may be a while before I know for sure, thanks for your help