I've posted previously about a hesitation my car has (1985 Camaro with a 383, HSR and Dyno Don's headers, among other things) at partial throttle. I also just had a rocker arm nut come loose and the rocker arm fell off while driving. I put it back on and readjusted it, haven't driven the car since that happened last weekend.

I haven't had any luck diagnosing it up to this point, I was doing some searching and there was a suggestion to try and find a cold cylinder, that maybe one wasn't firing properly.

I have an infrared heat gun, I took the car for a long ride and got it nice and hot, then parked it with the engine running and checked the temperature on each runner of the head, about 1" from the flange on each one. The temperatures are all over the place, I have no idea what this means (if anything):

1: 180 F
2: 160 F
3: 175 F
4: 235 F
5: 340 F
6: 260 F
7: 250 F
8: 290 F

Cylinder 3 is the one where my rocker arm (exhaust valve) fell off. Seems like I have 3 that are low, 4 that are pretty normal and 1 that is really high. These weren't the high temps I recorded but rather a rough average after checking each one for 5-10 seconds.

Do these numbers mean anything? How should I proceed?

 

Cylinder 1-4 colder than 5-8. Doesnt surprise me , there sometimes can be air fuel distribution issues with hsr or any front fed intake

What is the timing you are seeing at idle? How big is the cam? Could also be some reversion effects making some cylinders colder or hotter. Self egr effect

How do all the plugs look?

 

I can't remember where the timing is at idle, I'm going to have to check. I think I set the base timing at 8.

I'll have to look up my cam, but it's pretty mild.

I haven't pulled any of the plugs yet, that is going to be my goal for tomorrow.