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[x-rad]

Just picked up some very lightly used 3.0 liners, Venolia pistons, and Carillo rods.

Cost was very reasonable, but the tradeoff is that two intake valves touched two piston tops. On one, only the carbon was pressed down a little.

Pics here of the worst piston. No play at wrist pin and big end bearings look OK. Problem is that piston canted a little in the cylinder.

Here is a pic of a little curvilinear worn spot on piston crown ..very minimal but visible. rest of piston looks fine. On piston top, the carbon and about 0.5mm aluminum is smooshed down. Looks worse than it is because pistons were recessed on top for valves (good thing , too!!)


All other pistons OK. All liners OK.

What do you guys think...don't worry about it??

[5yearplan]

As long as the liners and pins are fine, I wouldn't worry about it. There was a girl I worked with once that had a Daewoo (econobox POS)... While on a road trip with her mom, the timing belt broke and they proceeded to drive probably 1000 ft or so, without realizing there was a problem, until all 16 valves were broken and the engine quit running (for obvious reasons). From what I have hear the valves get the short end of that exchange, leaving the pistons dented, but otherwise unharmed. Otherwise, have the top of the pistons ceramic coated, and they should be better than new.

[Mats]

Ceramic coating of the piston crown sounds like a bad idea, it's usually followed by problems with pre-ignition and death of the pistons.
Never coat stuff without knowing exactly what it will do and why.

Clean the pistons thoroughly, after that you can assess the damages, not always as bad as it first appears.

[brookstroutr]

x-rad,

For the deal, the slight dings are nothing. I'd simply call it "battle scars"!!! I'm going to start looking for the same or similar set up for my Verde motor for my 3.0 ltr swap. Engine's been here since last November.

Hey, did you guys see my comment to your post about radiator cooling fans and what I came up with?

[KingDom]

x-rad,
When a valve comes in contact with a piston the valve usually bends. But thats not all. To bend the valve does take some force which is easy for the crank to turn as the crank reaches TDC and the conrod straghtens. The valve comes in contact on the side of the piston with great pressure trying to cock the piston in its bore resulting in piston skirt damage, or some engine buiders use the term "piston skirt collapse". You can see if piston skirt damage has resulted by comparing skirt dimmensions from the piston that has made contact and one that has not. If no piston skirt damage has occured just smooth out with emery cloth the damage to the piston valve releifs.
Mechanics discover this after a top end overhaul to replace the damaged valves only to find the engine has horrible piston slap when the engine is started after the head is replaced.

[x-rad]

thanks for the comments everyone
will clean up and measure roundness

Probably won't coat tops though

The liner this piston came out of had a tiny groove which matched the little nick in the piston crown...will replace with a spare liner

I read that some early Venolia pistons are lightweight , the sacrifice being piston top not very thick...and these failed sometimes

that was my concern with the area of valve contact

[Greg Gordon]

I suspect they are fine. Those pistons are very strong.