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

 

Sounds like you're getting too much gas. Blowing black smoke is a sure sign of running rich. Even though it's not blowing smoke anymore, I'd still lean towards it running rich.

Stupid question, but is the air filter clean?

You may still have a small exhaust leak somewhere as well.

 

Check the timing with a timing light.
Is the distriburator a vacuum actuated one? Make sure its hooked up and the hose is in good shape.

I am thinking you have a timing issue. Maybe a sticky valve, however valve work should have corrected that. Do the valves tick at all?


How many miles on the engine? Stretched timing chain?

Too me it sounds like your not getting enough spark, at least not at the right time.

It could be the plugs your using require more juice then your electrical is pushing. Popping out the exhaust almost sounds like your detonating on the exhaust stroke. Check the spark to each plug.