Pistons damaged from valve slap. Still usable?

[sixsixtwo]

I took apart a block tonight from a 91 Talon that I recently acquired. JE pistons (unknown compression ratio) on stock 1g rods. From the looks of it, two of my valves are in good condition and two are very questionable. From what I've read, most of the time as long as the piston is not cracked or warped, I should be able to take a dremel to it to make sure I don't develop any hot spots. Problem is, I don't know if it applies to a gouge that deep. What do you guys think? Also, I took some pics of the crank, which looks to me like it was balanced? There's a lot of material missing and welds added in other areas. It looks a bit shady to me, but what do I know? Does the crank look pretty normal or was it a hack job? The engine was running when I pulled it, however I'm not sure how well it was running. I was planning on taking the motor apart to look everything over, then sell it. However, I don't want to sell a block that's going to give someone trouble down the line. Sorry if the pics are off focus, thanks!

 

[onesickcrx]

I would say take those pistons clean them up make a nice ash tray cuz that about what there good for that looks pretty deep just judging from the first pic sorry dude /ubbthreads/images/graemlins/banghead.gif

 

The crank looks just like a balanced one I've seen lying around the shop. Check your runout with a dial caliper with it sitting there in the block. Not sure if it will tell you anything about balance, but not a bad test in general. If the balance job was bad it would follow that the motor would be vibrating. Did it vibrate badly?

The reason you see welds is that they remove some metal in places, and weld in heavier or lighter metals in others. Whatever it takes to balance it. If you are taking apart and have a relationship with a machine shop, maybe you could have them check if it is well balanced?

As for the pistons.....looks like junk to me....not an expert though.

 

[1990ggsxnj]

Quoting onesickcrx:
I would say take those pistons clean them up make a nice ash tray cuz that about what there good for that looks pretty deep just judging from the first pic sorry dude /ubbthreads/images/graemlins/banghead.gif



Trash dude, even for stock boost. Stock sets are cheap, just grab some off of the board.

 

[spoulson]

That crank's been rebuilt before, judging by the two-tone balancing holes. You could have it rebuilt and perforate it with more holes when you rebalance it again. I would feel more comfortable with a different crank, IMO.

 

[TylerAdamson]

Just find someone to weld up the divots and then grind them smooth.

On a more serious not, DO NOT reuse those pistons. The divots will cause hot spots and will not last long. As for the crank, its just been re-balanced. Have a machine shop check it to make sure its still in balance and you should be fine to use it, or you could send it off and get it knife edged.

 

[sixsixtwo]

Thanks for the replies guys. I guess I'll just sit on the block for a while and figure out what I want to do with it. I'm just happy I decided to take everything apart to give it a once over before I sold it to someone. /ubbthreads/images/graemlins/banghead.gif Scary thing is the car ran with the pistons as bad as they are. /ubbthreads/images/graemlins/uhh.gif

 

Pistons are trash. You can do about anything you want with them, except leaving them in that engine...

Crank is just balanced(at least, it's supposed to). If you don't trust it, have it checked.

 

[fivestardsm]

Pistons would probably be ashtray material, but as for the crank, it depends on if it was balanced alone, or as a rotating assembly. If it was balanced by it self, then there should not be a problem. If it was balanced as an entire rotating assembly, then it would need to be cre-balanced to what ever pistons you put on them. Honestly, I dont see it as a likely to have been balanced as a rotating assembly tho, just because of the cost, and they only had stock rods in there.

Is the crank STD. size? or has it been cut? If it was cut, I would deffinetly lean toward getting a new crank (i.e. junk it). If its STD. then just have it checked for balance.