Piston skirt damage
Posted: Tue May 14, 2019 4:14 pm
The damage that is done to the skirt on the piston going to have any effect on how it will seal,and is it usable or can it be cleaned up and used.
Don Terrill’s Speed-Talk
Home of Racing's Best and Brightest
https://www.speed-talk.com/forum/
Piston skirt damage
Page 1 of 2
Re: Piston skirt damage
Posted: Tue May 14, 2019 4:17 pm
How does it measure ? That is probably the most important thing.
Re: Piston skirt damage
Posted: Tue May 14, 2019 5:43 pm
I'd turn the tangs off, measure it and run it.
What's the black stripe?
What's the black stripe?
Re: Piston skirt damage
Posted: Tue May 14, 2019 6:18 pm
That black strip is just the shadow of the oil ring groove,and measure the same as the rest of the pistons.
Re: Piston skirt damage
Posted: Tue May 14, 2019 7:03 pm
Is that a ding in the top of the second ring groove at ~ 5:30?
Re: Piston skirt damage
Posted: Tue May 14, 2019 7:27 pm
Ring lands look to be pretty beat up
Re: Piston skirt damage
Posted: Tue May 14, 2019 10:42 pm
Nope’the rod across from it broke and some little fragments bounced around and hit it,I have gotten another piston for the engine I just thought I would see if you all thought this one may have been ok.
Re: Piston skirt damage
Posted: Tue May 14, 2019 10:52 pm
i wouldnt use it
Re: Piston skirt damage
Posted: Tue May 14, 2019 11:44 pm
I figured he meant the vertical stripe. What's with that one? It's the one that obviously looks out of place and could not be mistaken for a harmless shadow. If that vertical stripe is also a shadow, there's issues there, either way. We all know it wasn't manufactured that way, whereas it's pretty easy to figure out that's a shadow on the ringland at the "bottom".
Re: Piston skirt damage
Posted: Wed May 15, 2019 6:17 am
If the ring grooves measure consistent and the rings can spin freely I would give the skirts a light polish with 600 grit paper and ATF to lube the polish work it and then run it.
What did the rod go south though?
What did the rod go south though?
Re: Piston skirt damage
Posted: Wed May 15, 2019 1:18 pm
mag2555 wrote: ↑Wed May 15, 2019 6:17 am If the ring grooves measure consistent and the rings can spin freely I would give the skirts a light polish with 600 grit paper and ATF to lube the polish work it and then run it.
I am with this. Depends on whether it is a bracket car or something that is run harder. Personally, I probably have run worse.
Re: Piston skirt damage
Posted: Thu May 16, 2019 11:52 am
When you've polished off the skirt's high spots, the few grooves don't matter(a little extra lube reserve 
), what's the clearance? Decide what's looks/cosmetic & what's necessary for ring seal and the skirt's load against the wall.
), what's the clearance? Decide what's looks/cosmetic & what's necessary for ring seal and the skirt's load against the wall.Re: Piston skirt damage
Posted: Thu May 16, 2019 12:24 pm
If they're a little loose but otherwise okay, you could have the skirts abradably coated by Line2Line or a similar process: https://www.line2linecoatings.com/
The circa 1970 TRW pistons in my 495" BBC had 0.008"-0.010" clearance after torque plate honing. L2L built them up to ~0.000". Haven't run it yet, but I have every confidence they'll be good..
The circa 1970 TRW pistons in my 495" BBC had 0.008"-0.010" clearance after torque plate honing. L2L built them up to ~0.000". Haven't run it yet, but I have every confidence they'll be good..
Re: Piston skirt damage
Posted: Mon May 20, 2019 7:25 pm
Measure the piston. With the lower skirt dinged up like it looks, most likely the skirt is collapsed.
Re: Piston skirt damage
Posted: Mon May 20, 2019 7:59 pm
The guys promoting measuring the piston are on the money, that bottom third of skirt band i have found in the past to be a sure sigh of a collapsed skirt to the point in worst cases the piston taper has been inverted.
CP can give you the original shape dimensions to check to.
Cheers.
CP can give you the original shape dimensions to check to.
Cheers.