If your car is running with a lot of KR when under WOT because you have to much boost, or your using low grade gas. chipping a piston is a possibility. This is why we say over and over again not to run a 3.4" pulley unless your scanning for KR.

You engine will run really bad, trust me, you will know something is wrong. The first thing we suggest is pulling all the spark plugs and inspect them. When a piston chips the spark plug is the first thing that goes. nothing else will do this, short of having the wrong plugs.


If you see a smashed plug, this is what you have.


Time for a new lower end, or a rebuild.

I am guessing that something just got added to the Todo List de Danthurs?

And what is that stringy stuff all over the end of the spark plug? Has the motor been sitting a while?

I little dirt. I'm parting out the top and rebuilding the lower.

I'm new to the L67 thing. I've had the L27 in my car from when I bought it with 61k and till a week ago when it had 217k.

I'm now swapping an L67. I'm getting headers put in (speed daddy) with a 3" exhaust all the way back, Autolite 104'*, 180 t-stat, and a CAI. I'm having the guy doing the swap tune it for me as well.

I'm planning a 3.4" pulley. With the headers and the CAI, do you think I'll have much of a problem with KR?

Like I said, scan for KR. Your engine with headers and a 3.4" might be OK, or it might not. Only a scan will say for sure. The biggest killer of engines is a 3.4" pulley on a stock engine with no scan.

Usually you won't know until you scan it.

With a smashed plug you will know. That cylinder wont be firing right.

Sounds good. The guy that will be tuning will be also do the scanning. I was hoping the headers would be enough to get me from 3.5 to 3.4.

It was mentioned in the "in what order should I mod my engine" thread that a shift kit is recommended. Is there a correlation to the shift kit and KR, or is it just a recommended mod in general?

I'm planning on doing some light SC and LIM porting when the car comes home from Ohio in July. I've heard that it helps significantly in reducing heat and thereby reducing KR. I have a decent amount of experience porting.

X..the steps you are taking are in the right direction. Although 104'* are a bit cold for the mods. I'd think 605'* should work well for you.

I had a "chipped" piston in a Regal I picked up. Ran decent, but blowing smoke etc. I went to test compression, #4 had 0psi.

The plugs 2, 4, 6


The head


The chipped piston. (I stood there laughing when I pulled the head off)


The piston rod and pushrod


Found the chip that came off the piston.


There was nothing but a wrist pin left in the cylinder. Which is odd because they should be free floating once the retaining ring is out of the piston ....or the piston is totally missing lol

On a side note.. if you take a little off a spare engine lift bracket, you can bolt it up for the win on connecting the leveler to the fourth corner.

Wow now thats bad. It just ate the entire piston lol