Jeep Strokers

Hello all,

Haven’t been around here in a while and lost access to my old email address so I had to create a new account. I currently am working on my MJ that has a built 4.0. Bore .060 stage, 1.5 cam (505), adjustable roller rockers, Edelbrock head, 99+ intake, 24lb injectors (I don’t remember the brand since I got them years ago) etc. Running 91 obd1 electronics and recoated iat sensor to stock air box. Having some issues with cooling. Before I throw the kitchen sink at the cooling system I’d like to get your input on these spark plugs. They have probably 5k miles in them and I just pulled them today. I’m getting a sneaking suspicion that I’m running a bit lean and that is the root of the problem but not sure yet. To start, can you give me your feedback on these plugs? I have them laid out from left to right starting cylinder 1-6. I flipped them over so you can see both sides of the ground strip. Uploaded in full resolution so you can zoom in. Thanks!

After 5000 miles it’s really hard to get an accurate plug reading.
To properly read plugs you need to put a new set in.

On race engines to get an accurate reading we put a fresh set of plugs in and look at it after 1 run.
With all of that said I suspect you have some lean cylinders.
Looks like you have pepper marks on the porcelain that would indicate detonation.

My .02