K5 blazer 305 popping sound

Hey all
I have a crazy problem with a 1986 k5. I just bought this truck and I am getting a popping sound out the exhaust. The guy I bought it from said the heads were redone not to long ago and it had a bad carb and a exhaust leak. It didn't have the popping sound then. I got the truck home and put new plugs dist. and wires, running ok no popping. I changed the oil and filter flushed rad and changed thermostate, still no popping. Next time I started the truck (about 3 hours later from changing oil) I came out to go to work got around the block and the truck started popping like crazy puffing black smoke and putting, made it to work. The next day pulled off the quadrajunk and put on a new edlbrock 1406.(all emmisons and computer has been disconnected) after the carb replacement the truck ran good but still has a intermitten popping mostly at idle. Well I thought maybe the distributor put new one in still popping. This truck runs great down the road but at idle it pops but not a miss. I need a answer
Thanks Mike

Check your timing.

Well When I put in new distributor I brought #1 to TDC but I can't locate the timing indicator tofinre tune the timing. I looked all over and only found mark on harmonic balancer. Where is it or should it be I believe its a bolt on right
mike

Well When I put in new distributor I brought #1 to TDC but I can't locate the timing indicator tofinre tune the timing. I looked all over and only found mark on harmonic balancer. Where is it or should it be I believe its a bolt on right
mike

There should be the timing marks on the crank.

sounds like you timing is way off.