Exhaust Popping After Plug Swap

[ruckusz28]

Ok so here's a little history. 350 crate engine in the car from the PO - I don't have lots of info on the specs. Anyhoo, over the winter i swapped the holley for an edelbrock 650. When driving last week, the engine was jumpy when held around 3 grand. I checked the plugs and they were all burned and nasty. I replaced them with delco platinum. Gapped to .040. I inspected the wires and there was no damage.

I started the car and it runs great.. BUT now there's a popping sound coming from the exhaust about every 5-10 seconds. The pop is only there at idle.

So far i've changed the wires and adjusted the carb. Today i'm going to play with the timing.

Super confused here.. What could it be?

[DETROITMUSCLE]

did you drop any plugs while in the box or out during the install? The porcelain can develop very fine cracks.

[ruckusz28]

now that you mention it, i did drop one. thought i had it threaded on the back side of the header and i was wrong.

[WMCCjames]

Jeff is right, you cracked a plug. You should see a fine black line on the porcelain where the crack is.

[ruckusz28]

I'm pretty sure i remember which one I dropped. It was luckily one of the easier ones to get at. I'm going to hate it if i have to pull and check each one. It was a big pain in the ace.

[ruckusz28]

So I went through the plugs and didn't find a crack. Found a little brown on some of the white porcelain and changed those plugs. Same issue. Any other thoughts?

[ruckusz28]

Figured it out. Previous owner had the firing order wrong. Re set the timing. Set cylinder 1 to tdc, ran the wires accordingly and she runs better than ever.