Engine popping under a load with HEI

[Towers21]

Im asking for troubleshooting help with an engine that the second its under a load after pulled into high gear starts popping and banging at full throttle and doesnt quit. At idle motor doesnt skip a beat, revs up and immediately back to idle no problem. Its a 358 steel bowtie head, roller. Valves are at 18 n 20 spec to cam, 750 BG 76 jets square no power valves, brand new wiring, battery, 50k volt coil and module in HEI, new 135's gapped at .035 and timing at 34*. Any help would be great. Thanks

[57m]

Hi we had the exact problem when we ran a limited late model with a hei ingnition idle it sounded great under load it would pop an bang we ran 360 13.1 compression with steel heads we tryed everything. The last thing we tryed was a different ignition system we installed a msd ignition box and coil and it was all fixed good luck.

[Towers21]

Yeah thats one option but not a legal one in this case. So lookin for a solution as is. Thanks

[let-r-eat]

Pinch the plug gap down to .015 would be my first move.

[monster777]

Msd p/n 83647 hei heat module. Best $100. Ever spent for an hei setup.

[JJ128]

The module is bad, no question about it.

[Towers21]

Both module and 50k volt coil are a brand new matched set. The same distributor ran once upon a time in a different car, not mine, same engine, ran with an Accel high volt coil but wasnt high enough. Ran up to 6000 rpm and basically like hitting the rev limiter. The original coil had gone bad but like I said its new.

[monster777]

Don't matter. I.d still bet that would cure your problem. We had same issue. Check to make sure cap isn't cracked also.

[TS3g]

It is probably the pick up coil. I've had this problem on my own car and seen it on others. Could also be a ground problem

[softshoe72]

Your distributor wires are proably backwards

[Towers21]

TS3g What are you refering to as the "pick up coil"? Wires are not on backwards. Thanks for replies Anyone else please read the original post Thanks

[TS3g]

Its what actually triggers the ignition to fire. Google HEI pickup coil testing to see how to determine if yours may be bad. They are pretty cheap from auto parts stores and are easy to replace as well. I can't for certain say that is the problem, but both myself and my dad have had the exact issue you described and that was the problem.

[Racer63]

Let me ask this. I had same problem but it would clear up after a lap or two in warmups. Replaced plug wires, cap with new coil, new module, and new rotor. First night out it ran fine. Since then it pops for about a half a lap in warmups and then is good for the night????? Moisture?

[Bubstr]

Electricity follows the path of least resistance. High compression and standard plug gaps, put resistance in your ignition system, but we want them. So we have to optimize the rest of the system to make the electricity go there. This includes a good module, good water tight cap, good plug wires and connectors and a good coil. Now if you want to find your weak link, Start car, Hang a blanket or tarp around hood to make it dark. Put someone in the drivers seat applying power and brake, to simulate load and start spraying water on plugs working your way back to distributor and when you sprat the weak ling, it will light up showing the weak spot. If none, it;s probably the module. This may be old school, but still works. Look for the light show.

Most times it's cheap wires or unsoddered ends or long stretch of unsupported wires that vibrate and crack the insulation.

[ALF401]

We had run the power wire from the battery to a toggle switch then to the Hei distributer. Had the same problem for two weeks changed everything including the distributer. Finally change the toggle switch and it was that. Poor connection but not a problem until we put a load on it.

[RACR_73s]

Try the toggle switch for the ignition next to the push button for the start. Happened to me a few years back and I chased it for several weeks at the end of the year and through all next years practices. Lots of frustration for a $5 part.

[Bubstr]

Try the misting from the windex sprayer. It makes them shorts show up. If it's popping, you have a spark jumping. You can't ride on the fender under load, so you help the short show you where it is. If it's popping, that indicates a wrong cylinder getting spark at the wrong time. Look to spark jumping from wire to wire or cap or coil.

This method does two things. It puts some load on the engine by revving and braking, even if it don't pop and bang and it helps conduct that spark jumping that causes it. Try it, you'll like it.

Last thing use good wires with soldered ends and never pull wire off a plug with the wire.

[LimitedLM06]

had a buddy have the same problem last year. Bad toggle switch was the problem.

[LimitedLM06]

remember that an HEI MUST have 12 volts to run properly. any less and you have problems.