Black Deposit On Top Of Pistons

[Shovelrick]

I have a 3 yr old very low mile but lots of idle running, adjusting things time BBC, 10.8:1 comp. Holley 850 & HP 1,000 (on it now and during dyno) and I have what looks like either black carbon or oil on the piston tops, what can I use to clean this off WO taking the heads off? Techron in the gas? I use mostly 91 oct, sometimes 93 and always Sunoco Non Eth

 

[Nashville Cat]

I'd put 2 to 3 bottles of Techron in a 1/4 tank of 93 or higher octane. Take it on the interstate and drive at 3000+ rpm for 30 minutes minimum.
Are you looking at the pistons with a scope through the spark plug hole ?

 

[77cruiser]

Get going on those long smokey burnout vids, that should do it.

 

[Shovelrick]

I'd put 2 to 3 bottles of Techron in a 1/4 tank of 93 or higher octane. Take it on the interstate and drive at 3000+ rpm for 30 minutes minimum.
Are you looking at the pistons with a scope through the spark plug hole ?

Yes with a Bore/Endoscope in a spark plug hole, I might have a pic

 

[JohnC]

I know nothing about it but would running some Seafoam help? I think there are two ways so do it, in the gas tank or gently sucking through a vacuum port on your engine. I did this once on my old Accord and it was laying down a smoke screen for 20-30 minutes. I’ve also heard of people sucking hot water into the engine and as they described it, “steam cleaning” the engine.

I’m curious too because I have a low mile small block and was surprised that the tops of the pistons and valves and combustion chambers had some black coating. Most of it scrubbed off pretty easy with a scotchbrite pad and a little water, so it’s not like it’s super adherent.

 

[JohnC]

 

[JohnC]

This guy does several lawn mower videos related to decombonizing combustion chambers with various methods.

 

[Molly's 70]

I've always used BG44k or Techron.