rufretic

iTrader: (37)

I have a brand new block and pistons. I ended up having ptv clearance and notched my new pistons trying to start it. It's on all pistons but pretty small marks. Now I'm not sure if it is ok to run them the way they are or what I need to do to repair them. Please help.

Here is what the worst one looks like.

The Alchemist

iTrader: (19)

Well, first things first, what did you do to increase your piston to valve clearance so that it doesn't happen again?

I'm no expert, but maybe some emory cloth on the high spots, and sharp edges to reduce the possiblity of hotspots and you should be okay. Once it runs for a little while, the carbon will build up and smooth out the spot.

rufretic

iTrader: (37)

Changing heads and possibly cam. I'm only worried about the fixing the pistons right now.

bjamick

iTrader: (31)

Pistons are fine, its your valves that are prob bent.

teke184

iTrader: (5)

smooth them off and don't run n2o or boost

LSWONGTO

iTrader: (3)

What are the specifics of your setup if u don't mind sharing.

rufretic

iTrader: (37)

Um, yeah that's not going to happen. Try 30psi. These are boost pistons. They came from diamond with valve reliefs, they just where in the wrong spot, so I don't see how having the small indentations, smaller than what came from the factory, is going to be a problem. I'm going to smooth them out and call it good.

rufretic

iTrader: (37)

Hope you don't mind reading lol. You can find details here:
https://ls1tech.com/forums/forced-induction/929781-lsx-ready-dropped-tomorrow-pics.html

00pooterSS

iTrader: (40)

That will be fine, there are plenty of people that take aftermarket pistons and sand down the sharp edges along the valve reliefs, as long as there is sufficient metal left when you are done sanding it will be fine. Those will be detonation magnets though if left that way.


Just dont bring that area any closer to the edge of the piston, sand it down smoothing it into that part of the valve relief and boost the **** out of it.

rufretic

iTrader: (37)

Cool, that's what I wanted to hear. They aren't very deep, the mark in the center I can probly just sand till it's gone, nice and smooth. Do I have to worry about the balance or is it not enough weight to matter?

00pooterSS

iTrader: (40)

Now that I would ask someone of more experience in the matter than myself, that is a great question though, to be safe, take them to a machinist and have them weighed after or have him do the cleanup and weigh, you can pull the pistons yourself easily if the wrist pins are not press fit which if you have forged internals I would assume they are not press and just have lock clips, I would ASSUME they would be fine, if you dont want to go into that much depth then try to sand them evenly ( take the same amount off of all ), I would think it would be ok, that is only going to amount to a very very small amount of weight, surely less than a gram, I have no idea what the acceptable variance is in weight though so my opinion on this is just that pure opinion, not coming from experience or 100 percent knowledge.

You know what on second thought with all the money in it bite the bullet and pull the pistons and take them to be smoothed and weighed. Vibration from being out of balance could be detrimental, if that thing gets into a harmonic vibration because of the balance that wouldnt take long to destroy it all.


EDIT: how do you think the valve got that far off the relief though? thats nowhere close to being "in" the relief...... I dont think that is just a clearence issue, have you looked into that yet?

rufretic

iTrader: (37)

"EDIT: how do you think the valve got that far off the relief though? thats nowhere close to being "in" the relief...... I dont think that is just a clearence issue, have you looked into that yet?"

I have no idea why it doesn't line up with the relief. The only thing I can think of is that the relief was made for larger valves. I didn't have them cut for me, they just came that way.

00pooterSS

iTrader: (40)

That is the first thing I would be trying to figure out, actually I would call the vendor and say hey you sold me some pistons that have valve reliefs in the wrong area, can you send me a proper set???? then all your problems are solved. Surely the pistons are not in backwards so that the reliefs are backwards..??... maybe something to look into, I cant tell much by your picture of which end or direction I am looking at to tell you.

rufretic

iTrader: (37)

Not a venders fault, I got them second hand. That wouldn't solve all my problems anyway, install & rebalance = $$$$

00pooterSS

iTrader: (40)

Well that sucks. As far as more machine work the rings are already gapped, they can go back in, pistons are easy to R&R you can do that yourself so the cost shouldnt be too high. Sorry to hear about the situation, have you called the machinist that built the motor about this yet to see what insight they can offer you?

crashinaz

iTrader: (35)

Find the problem and smooth the nicks out. NOT a problem. If that's the worst piston, you've got NOTHING to worry about. Once you get it up, running and making passes with it... You'll look back and laugh about being so concerned about it... Been there. Good luck man.

rufretic

iTrader: (37)

Thanks man. That actually makes me feel a lot better especially after seeing your running a simular set-up. I'm just so paranoid after running into problems that I've got myself so worked up and worried. I hope your right.

LLC

Have you all gone MAD?

The man never got the engine started and the PTV issue came when just turning it over. What happens when the rotating assembly gets to spinning while the engine is running?

Crankshaft deflection, centrifugal force, expansion from heat, valve bounce, and more is going to be the death of your ****. PTV will clearance itself no doubt and it comes in the form of bent or broken valves and taking out pistons along with any breakage. PTV clearance decreases with heat and RPM. YOU ALREADY HAVE ZERO PTV CLEARANCE WITH NO START UP!

How thick is your head gasket? How far in the hole are the pistons?

mvvette97

iTrader: (18)

Pistons look fine but you have a huge problem. Either your cam is just massive or it may of not been times right. I have seen an eyelash in pistons from not flycutting but nothing like that. Looks like the valve just plowed the piston. What are the cam specs and are the heads milled? Are you sure the dots were lined up on the timing set? A friend of mine had his off one tooth and it kissed the pistons but nothing like yours.

rufretic

iTrader: (37)

Gaskets are .04, not sure on the pistons. It's a 4" bore, 4" stroke, lsx block with stock 317 heads. The cam is pretty massive, 246/250 .632/.635 on a 112+4