I have a weird ignition problem. I have brand new MSD superconductor wires, a flamethrower HEI coil, I cleaned up my cap and rotor with a little wire brush on my rotary tool, and all the spark plugs are connected nice and tight. When I give it more than half gas and dip into the secondaries the car starts popping and sounding like total ****! Seems to only happen past 4,000 rpms. Car drove PERFECT last week, now this. I didnt' change a thing. Its not the wires. Its not the carburetor ( I tested three different carburetors just to be sure), and I don't think it could be the cap/rotor cuz I just cleaned those up. Does a bad HEI module make problems like this? The module is somewhat old....but not really that old. Timing is set dead on, and I varied the timing just to check anyways, its not the timing. Car drives perfect unless I stomp on the gas and go past 4K rpms, then it sounds like total crap. It still goes....but it just kidda pops and farts out the exhaust, it doesn't like TOTALLY bog and backfire..nothing like that...but it makes little popping noises and is MOST definitely much slower than last week.
Chris

 

What you can do is make a run to a local autostore and get a new module, install it, and if its not it then you can still return it cause they will never know it was used. Did you check the timing? There also might not be enough contact between the rotor and the distributor points if you cleaned them up too well. That's all i can think of, good luck.

 

Timing is good...I did notice this: cap has a lot of play in it, its an accel cap, and we all know how crappy accel HEI products are. But I dont see why it would start acting funny all the sudden, its always been kinda loose like that. Not LOOSE, just has a tad bit of play in it even when the cap is bolted down. I'll try the module and new cap/rotor jsut for the hell of it.

 

Nothing has fixed it! Need some more advice...car has to be fast again for Friday night darnit!

 

I think i know what the problem might be. You said that the cap has been tightened pretty good to the distributor and it still has play in it. That would mean that the distributor is loose, not the cap. There is only one bolt holding the distributor down tight against the manifold, so its pretty common for it to get loose (happened to me once). You might need to use a distributor wrench to get to it if you have a lot of accessories. If that's not it then i would get your coil tested, and get a new cap too. Did you gap your spark plugs too much by the way? I've heard somewhere that MSD's are known to cut out at higher rpm's if the gap on the plugs is too big, but that's just something i heard.
p.s. did you install a new cap?

 

I had exactly the same problem New coil didn't solve it, so I replaced plugs and leads and it went away.... Since then I have also changed the pick up coil, rotor arm and distributor. It was exactly the same mis fire, I would only notice it at full throttle at about 4000rpm upwards.

I have a HEI set up with Accel super coil (that mounts on the cap) I used spiral wound 8mm MOROSO wires (very good) Make sure your leads are well seperated too, especially 5 & 7.

Hope this helps, I know how annoying it is, I lost to a Porsche becuase of this

 

is the vaccuum advance hooked up and functioning????? Also check the "button in the cap that contacts the rotor. Sometimes this gets carboned up....

 

ZZ42fast...this is prolly a dumb question...but what is "leads"? Did the problem fix cuz of the plugs or "leads?" I'll changing the plugs I guess.
Chris

 

Plug leads or wires, connect the plugs to the distributor... It made a difference to me

Good luck!

 

Make sure th gaps are right on the new plugs and get the new plug wires or leads, it should sort you out.

 

I have had this exact same problem for months. I have spent hundreds, maybe even a grand total replacing everything I could think of because I was convinced it was a fuel problem.

I have a S10 obviously with a mild 350, after reading this post, for ***** n giggles I just walked out to the lot on my lunch break and unplugged my tach.

Truck wouldnt even idle after doing so, had to retune the carb really quick, then went up to the store to get a sandwich for lunch.


Holy **** I'm still shaking. 2500lb truck and fully spooled 4.11's that I have been able to actually use for the first time. I'm in love all over again.