Thumpn

I have a 5.3 with twin HX35 holset turbos and custom forged 30cc dish pistons, now my question is got me baffled and I was looking for some input.

I thought something didn't feel right in the gut so I did a comp check on my cyl's and they all check out with the same comp test psi (dry), I checked my plugs and wires and all check out good, I even tested my coil to make sure it was firing with a good spark, so I pulled out the borra-scope to take a look at the pistons, but for some reason I have 1 cyl (#3) that the top of the piston is clean, but the other 7 have a thin consistent layer of carbon build up on them in the dish of the piston. Have any of you seen this at all? or Know what might be the cause of this?

I can tell you that I have a wide band on both sides of the motor and they have been very consistent in the reading at a solid 11.5-11.7.

Any suggestions would be helpful?

Thumpn

oh and one thing I forgot to mention was I am running a blow thru carb.

Thumpn

Bump, Anyone?

stevieturbo

Clean piston/chamber can often be a sign of water ingress. It basically steam cleans things.

87silverbullet

iTrader: (11)

What did that plug look like on that one cylinder compared to the rest?

Thumpn

it had a slight golden brown coloring but just a hint lighter than all the others. I have been thinking that it might be getting more fuel than the rest and is washing the cyl.

87silverbullet

iTrader: (11)

If it was getting more fuel than the rest it wouldn't be lighter brown. Especially since the rest were darker. Like stevieturbo said you might be getting water in that cylinder that is steam cleaning things.