Curious to know if most people have oil on plug threads when they chnage plugs or inspect them?

I am pretty sure most of my plugs have oil on the threads. I am just trying to diagnose 2 cylinders that are fouling the plugs.

I have been using NGK BP4FS plugs but now I am thinking of changing to the AC Delco R45TS and see if they are any better.

Cylinders 5&7 are the ones that are fouling.

I have done a compression test all cylinders checked out fine 200 PSI +- 10 PSI so overall very close.

 

200psi for a compression test is a little too high. Should be like 170-185 all around.

But then again, what compression ratio are you at and what cam are you running?

 

I am pretty sure the engine is to stock specs for an 86. I don't know 100% as the engine in the car now is a rebuilt one and I presume they built it to specs becuase the used a 305 again when they could have put in a 350 for the same price.

So basically stock 305 with peanut CAM etc.... All I have done is headers, PROM tuning, Air foil, MAP conversion, ECM change.

If I remember correctly some PSI values where above 200 like 210 but nothing was lower then 190.

I just found the actual numbers from the compression test here they are.

LHD side head (from back of engine to front)

4. 210PSI
3. 210PSI
2. 200PSI
1. 200PSI

So numbers 3&4 are the cylinders that are founling up. The buildup on the plug looks like soot. Almost like little black stones.

RHD side head(from back of engine to front)

4. 190PSI
3. 192.5PSI
2. 198PSI
1.198PSI

 

Can I put in 2 hotter plugs in those 2 cylinders only and leave the colder plugs in the rest of the cylinders or is this no good to mix and match plugs?

 

doesn't hurt to mix plugs as long as they work. your engine is really a combination of 8 differant cylinders working together.