Need help guys, I have a 70 350/300 4 speed . I have an intermitent pop out of my passenger side exhaust at idle. I have changed Carb, wires, plugs,switched to Petronix ignition.The tcs works fine. I even disconnect the main vacum to the vacum tank no, difference  Heat riser wired open,timing is perfect,compression test perfect. It has 44000 orginal miles, the car runs perfect.Everything is stock except for the ignition.Any sugestions besides turning up the radio .  Thanks

Hmmmm....
Ear plugs?
sorry...it couldn't be helped...)

Couple of things I can think of...
The EGR valve could be causing this, but perhaps not at idle.
An exhaust leak at, or very near the ex. manifold could do it, too.

How intermittent is it? Does it pop when decelerating, too?
A sticky valve, even with good compression, will cause a pop if it happens to stick at the right time. Sticky valve, lifter pumped up too tight, or even weak valve springs...any of these can cause it.
At 44,000 miles, I wouldn't expect a valve guide to be that worn, but that's another possibility...(it could cause the valve to not seat properly)

Just a quick story. My father, between machinist jobs, worked as a service manager for a local GM dealer in the 70s and 80s. There is a community near us called Green Valley, its a retirement community. For some reason, these older ladies would always but prerformance cars as their daily drivers. Corvettes, Nova SS, Chevelle SS, Impala SS, Camaor RS, SS, etc. They always came to my dad when the crsa stopped running right, it seemed to be about once or twice a week (not the same cars, mind you, just different ladies). They always LOVED the cars after he did his special tweeking.

Are you, sir, suggesting that Tom's car might just need a wee bit of "pressure testing" on the hi-way?



Shoot...I have to do that every time I get into Mama's Cadderack...just needs a little cleaning out....

Also check you plug gaps. I once had plug with a closed gap that happened accidentally when it fell to the ground during install. Stupid me for not checking the plug but - when decelerating the cylinder would load up and pop from all the fuel not igniting and eventually blowing from the cylinder pressure and heat....

Thank you for your suggestions.I have tweeked the carb a liitle bit and found 2 exhaust manifold bolts not really tight. On the last ride it didn't do it, but it still may this time. It seems to do it more when its cold.Just the passenger side though.I am going to take Mikes advice also and take it for THRILLING RIDE.  Thank Again,   Tom