Exhaust pop

[wjsan]

My 413 is having a new issue. It has a pertronix conversion including their coil. Worked fine last year and until a week ago, no problems. The ballast resistor is bypassed with a soldered wire. Runs fine when cold, as it reaches operating temp, it starts to exhaust pop and lose power. I thought it was a vacuum leak at the carb base, so I tightened it down. A couple of the bolts needed tightened a turn or two. I took it out again today and when it reached operating temperature it did it again. This time shaking at a stop light while idling. I am thinking of changing the coil. Any advice?

Thanks

Bill

 

[Belle66]

Over the years, I've had several ignition coils give the problem you're experiencing. They start to go bad when they get hot.

 

[wjsan]

Over the years, I've had several ignition coils give the problem you're experiencing. They start to go bad when they get hot.

Thanks, I will change it that is what I thought.

 

[Mike67]

Are you sure it's not detonation?

 

[wjsan]

Are you sure it's not detonation?

I run premium fuel and add Lucas oil octane booster. I also use lead substitute, fwiw. Again it only does it when I am moving and up to operating temperature. Right now when it idles or is revved it does not pop.

 

[vance.dykes]

moisture under dizzy cap ? crack in dizzy cap ?

 

[440Coronet500]

Watch using the lead substitute, that stuff will make your rings stick in the piston grooves! If you're heads have hardened seats there's no reason to use it! 440'

 

[wjsan]

moisture under dizzy cap ? crack in dizzy cap ?

I will check that again, too. I checked it the other day and it didn't look wet or cracked. Thanks.

 

[Mike67]

Are you sure it's not detonation?

Was just curious since it only happens once up to temp. Did not know if you possibly changed the timing when converting over to the Petronix diz...

 

[wjsan]

Watch using the lead substitute, that stuff will make your rings stick in the piston grooves! If you're heads have hardened seats there's no reason to use it! 440'

440, The heads do not have hardened seats. I am using the redline lead substitute.

 

[wjsan]

Was just curious since it only happens once up to temp. Did not know if you possibly changed the timing when converting over to the Petronix diz...

I did not change the timing.

 

[oldbee]

Sounds like coil. Heat riser not stuck shut?

 

[Don Frelier]

Unless you checked and corrected the timing, it could be different following a conversion.

 

[Moparnocar]

I had that same thing kind of happen on a 383 years ago. Tried and adjusted everything. Seemed like it was popping out of a few cylinders and I could hear it in a couple of header tubes.

called the machine shop to talk to The Machinist who rebuilt the heads and he was no longer there, he was fired... turned out he was doing shoddy work and I had to have the heads redone some reason the exhaust valves were leaking after awhile

 

[wjsan]

Sounds like coil. Heat riser not stuck shut?

No heat riser on it. I am running stock 440HP exhaust manifolds.

 

[wjsan]

Unless you checked and corrected the timing, it could be different following a conversion.

I reset the timing after I converted from points to the ignitor.

 

[wjsan]

I had that same thing kind of happen on a 383 years ago. Tried and adjusted everything. Seemed like it was popping out of a few cylinders and I could hear it in a couple of header tubes.

called the machine shop to talk to The Machinist who rebuilt the heads and he was no longer there, he was fired... turned out he was doing shoddy work and I had to have the heads redone some reason the exhaust valves were leaking after awhile

I hope this isn't the case but I shall find out after I change the coil and a couple other things. Thanks for the reply.

 

[coloradodave]

Rather than throw parts at it, how about diagnosing the coil with a multimeter? Google is your friend...

 

[Moparnocar]

I hope this isn't the case but I shall find out after I change the coil and a couple other things. Thanks for the reply.

No prob, if coil doesn't do it, do a leak down test, cold and hot