Popping out the tail pipe

70 Challenger 410 stroker is popping out the tail pipe when first started (cold). Then goes away when warmed up. I thought exhaust leak but can't find one, very thorough can't find any leak Any thoughts

Not sure but I'm wondering if a particular cyls' (one or several) mixture ain't being from either too rich or too lean (I'd think too rich) then it is being ignited further down at the tailpipe and that is the popping. Just thinking out loud & here's a BTT for ya.

How does it run when you hear it popping ? Does it feel like a miss when it pops ? Ron

I had that problem when I had a Holley,, got rid of that problem gone!!!