Bad miss - could use some thoughts from y'all

[BigT]

My 350 developed a very bad miss a couple days ago, like it dropped 1 or 2 cylinders. HEI, mild cam, bought it used last fall, ran great until this issue, though it has been dieseling a bit when I shut it down hot. Plugs are new, wires and cap are all attached and in good shape, so I do not suspect and ignition issue - though I suppose it could be a bad module. My next course of diagnostic action is to check compression and go from there. Any other thoughts or things to look for?

BigT

 

[fast 99]

Can remove plug wires one at a time running to possibly isolate cylinder.

Checking compression might narrow it down.

A vacuum gauge is a good diagnostic tool for misfires, faster and easier. Many times will show a mechanical fault.

Check for vacuum leaks.

Dieseling suggests a vacuum leak or high idle.

Disregard the line.

 

[77Dmax]

Get an infrared thermometer and check temps at the exhaust ports. Your cold cylinders are the dead ones. Start diagnosing from there.

 

[Ricko1966]

Get an infrared thermometer and check temps at the exhaust ports. Your cold cylinders are the dead ones. Start diagnosing from there.

I do the same with my fingers have for like 30 years wet your fingers touch the manifold,use common sense. Some ports will sizzle,some won't.

 

[77Dmax]

That works too.

 

[Ricko1966]

That works too.

Only mentioned it because infrared thermometers didn't use to be cheap,and not everyone has one. But absolutely, checking exhaust temperature no matter how, is a fantastic diagnostic tool.