Exshaust

[Steven Smith]

My problem is this. I'm running a 440 six pack with 292 cam and it's popping through the exshaust at idle. While driving its pops when accelerateing but if you do it slow it's fine when you let off its fine , Out on the road at speed you can drive the piss out of it no problem. Has new cap and button, plug wires, plugs, coil.

 

[Kern Dog]

A few things could be to blame. There may be a few tiny pinholes in the exhaust system allowing fresh air to be drawn in. These mix with the exhaust and may burn IN the exhaust stream, causing the popping.
Also, retarded ignition timing can cause late combustion....which allows more unburned fuel to pass through the exhaust and actually combust in the mufflers.
That 292 cam...Is that the 292/509 MP cam? If so, it really needs a LOT of initial timing to run right. I'm talking at least 15 to 18 degrees of initial timing or the symptoms that you describe are almost guaranteed to happen.

 

[Kern Dog]

One more thing:
Any performance cam you use will likely need MORE initial timing but the drawback with that is that with a stock type distributor, this moves the total timing to a "waaaay too high" 40-45 degree setting when the advance curve is factored in. This means you need to modify the distributor to "narrow" the advance curve. The MSD systems (And some others) allow this mod easily but the factory distributors require more work to get this done. Post up more specs of what you have and you'll get some results here. There are some pretty sharp engine guys on this message board. Good luck.

 

[Steven Smith]

I'm running 18 degrees advance with a aftermarket electronic distribitor the cam is 292/509

 

[moparnation74]

Any crossed plug wires?

Need more engine specifics......

My initial thought was the lash being out of adjustment......but I dont know all your specifics...

 

[khryslerkid]

Make sure your plug wires haven't backed off of any plugs. I was using msd wires and they would back off the plug after a couple of heat cycles. Looked like they were still on until I grabbed one and noticed it wasn't attached by the wire end, just the boot. That makes a popping sound in the exhaust.

 

[Steven Smith]

I've cked the wires and I'm running accel 8.8 300+ ferro-spiral race wires it's just gotten above my knowledge.

 

[khryslerkid]

I've cked the wires and I'm running accel 8.8 300+ ferro-spiral race wires it's just gotten above my knowledge.

So has this popping just started or has it always been there?

Solid lifters?

 

[Steven Smith]

I had it did a complete tune on the car and it went away and when it came back it was worse and I've been unable to to find the problem. I'm not running solid lifters.

 

[khryslerkid]

I had it did a complete tune on the car and it went away and when it came back it was worse and I've been unable to to find the problem. I'm not running solid lifters.

Are you running points or electronic distributor?

 

[Steven Smith]

Electronic

 

[khryslerkid]

Electronic

Timing without vacuum advance hooked up around 16*-18*

 

[Steven Smith]

18 advance

 

[Steven Smith]

thats with everything hooked up that's with everything hooked up

 

[khryslerkid]

thats with everything hooked up that's with everything hooked up

You need to set the initial timing 16*-18* without the vacuum advance hooked up, and plugged off at the carb. 18* with the advance hooked up will probably not be enough timing causing the popping.

 

[HEMI-ITIS]

Check that it's not a lean spike!

 

[Steven Smith]

Will do thanks