Combustion Chamber Buildup

[HDBD]

Have a look at this chamber. Customer stated he runs 5 gal of premium and 1 gal 110 octane per fill. Comments?

[HDBD]

One more

[Schurkey]

What's the quench/squish distance?

[Frankshaft]

That's generally oil contamination. Figure out why it's oiling the chamber so much. Rings, guides?

[Calypso]

Looks like a wet flow problem. Fuel collecting to the port walls being pulled into the chamber. More towards quench pad side, where velocity is higher (pressure lower). Improving atomization and balancing pressure differential across the port could help.
Seen similar thing in one side quench 2v hemi head and and did a flow and a crude wet flow test, which seemed to agree with carbon formation. In the pad side the carbon reached the rings and that's where most of the pooled liquid was going.

[Warp Speed]

Oiling bad IMO.

[user-30257]

Oiling bad IMO.

Oh no. Clearly a wet flow problem, not thinning all the oil in the chamber to burn.

[hoodeng]

Bore condition/rings , the oil coming past has dissolved the carbon around the o/d of the piston crown.

I take it this is a 110 or 113? Have you determined why it is wet under the rear ex port?

Cheers,

[Dutchman]

Appears to have a lot of oil in front of the oil return by the exhust port .if it's leaking out it's leaking into the chamber as well.

[hoodeng]

It has MLS gaskets which seal as good as you get but the head surface has been turned in a lathe and looks to have a track in the finish.
This would not normally leak into the chamber , and as pointed out before the carbon is dissolved nearly 360° of the piston crown o/d which is oil passing rings territory.

Cheers.

[slo-svt]

Any details on the engine. I take apart oe engines fairly often and modern day pump fuels leave behind some pretty nasty deposits. I have seen tightening the quench go a long way for cleaning the deposits off the piston and chamber.

[HDBD]

This is a 4.165 bore twin cam. Pistons are Diamond Racing set at .003" Total Seal conventional rings, 1.5 x 1.5 x 3mm. The quench is .030. Not much of a shelf with these heads. Lost a head gasket due to improper torque. It is fixed and back on the road but I am recommending a refresh this winter. Will hone it in plates and use Line2Line with about a .002 buildup. Already have new file fit total seal rings. Went with higher than standard oil pack ring tension. This is an 11.5 motor and the guy puts miles on it. Oil control from the top is not the issue. Thanks for the comments.

[Calypso]

Chamber and valves look pretty clean for an oil burner.

[user-23911]

The headgasket is leaking where the oil feed is.


Loose bolts?


You didn't check?
As you pulled it apart?

[mag2555]

It's also signs of Exh reversion !
I bet if you flow test the Exh port it flows nearly as good in reverse as it does in the normal direction!!