Cylinder Galling - Why?

[Brktracer]

Jr. Dragster engine, ZR3 block, basic 8.90 combo. Complete brand new package, 1 yr. old.

I pulled the head and the cylinder is galled on the thrust side, actually both sides. It has been like that since about 35 runs but we ran it anyway to finish the season. Long story as to why I had the head off after only 35 runs! It is smoking a little and shows signs of oil consumption on top of the piston and in the combustion chamber. Based on some carb modifications I made late in the year and significant improvements in ET, it has been running lean.

I pulled the piston fully expecting to find a galled piston and stuck rings. That was not the case! The piston skirt looks perfect. No wear at all. It does show sign of excess heat as there is some straw coloring. The rings are not stuck and the rings look fine, surprisingly. Piston is only compression and oil ring design.

I'm not sure why the cylinder galled but the rings and piston are not affected. Some possible causes?: 1. Lubrication - too much alcohol/water in the oil. I do change it after each race. I would think lubrication issue would damage the piston? 2. Material incompatibility between the rings and cylinder material. It appears the top ring is chromed, but I'm really not sure. 3. Insufficient ring gap - usually this breaks the piston, but this piston has a rather large area above the top ring.

I was told, "They all do that." I'm not buying that. (pun intended)

I've learned one very important thing in this entire experience - I'm building my own engines from this point forward! There have been multiple issues. Next time it will be my fault!

Thanks!

[mag2555]

Does the galling only follow the path that the rings travel?

[mag2555]

Does the galling only follow the path that the rings travel?

[FuelieNova]

Any pics?
Tom

[Brktracer]

Does the galling only follow the path that the rings travel?

That's a great question! From picture it looks some galling above the ring path. Maybe just the crown of the piston expanded due to running lean? Pics below.

[Brktracer]

After looking closer at these pics, probably lean caused top of piston to grow oversize.

And..OMG is that porosity in that rod?!?!

[Kevin Johnson]

...
And..OMG is that porosity in that rod?!?!

...

Powerpost beetles.

[englertracing]

The ring lands shouldn't be touching the bore.

Also check the ring back clearance
The ring should be able to to completely recede into the piston groove.

[mag2555]

Yes lean, but also the burn pattern has the valve side of the chamber running a heck of a lot cooler so the piston is not even expanding evenly !

[hoodeng]

That does not look like galling, galling is metal transfer between two working surfaces, you have no evidence of this on the piston.

That looks more like oil contamination, the bulk of the marking starts right at the travel point of the lower oil ring rail and drags down the bore.

There looks to be contaminant in the piston skirt.

Cheers.

[SchmidtMotorWorks]

About that rod, talk to Nick Woods, he has some amazing looking rods for the engines he builds.

[Brktracer]

Rod looks great. I don’t know why the picture looks like that! It’s had me concerned all day.

There is wear all the way to the bottom of the cylinder and some signs past the top ring travel.

It’s got to be from lean and water/alky in the oil.

Top ring does not bottom in the piston.

End gap is too tight. It’s only about .008.

I think we’ll do next bore size (~.020”)piston, rings, rod. Gap ring to .014”. Wiseco minimum is .012”.

[Kevin Johnson]

That does not look like galling, galling is metal transfer between two working surfaces, you have no evidence of this on the piston.

That looks more like oil contamination, the bulk of the marking starts right at the travel point of the lower oil ring rail and drags down the bore.

There looks to be contaminant in the piston skirt.

Cheers.

I downloaded the pic and resampled it -- going from 300 dpi to 900 dpi -- and it looks like there is a very thin layer of melted/smoothed aluminium. You can see the other bits of contamination in the oil speckled around.

[Nut124]

FYI, the cyber security SW in my two PCs block and alert of the OP's pictures in this thread at www dot minpic dot net. My work computer does the same.

Make what you want of this. All I can tell is that this is highly unusual in my experience. I have never seen this before with speed-talk posts.

If I google the site www dot minpic dot net, it is blocked as unsafe.

Beware. And keep your AV SW up to date.

[Brktracer]

Thanks. Just tried to find a quick site. Please recommend a photo hosting site and I will change them.