Wiseco pistons

[Force Fed Mopar]

Are they supposed to be elliptical? I know the stock ones are. I'm working on fixing Bozo's car, got the pistons out that have less than 5k miles on them, and #1 and #4 are done, the ring land area has bad gouging and the rings are stuck in the grooves. #2 and #3 pistons look like new, all 4 holes look ok. Used one of the good ones to check the piston clearance, I get .003 on the thrust side and .015 on the side-to-side surface in each bore. The piston measures 3.479 front to back and 3.464 side-to-side (if looking at it in the installed orientation).

I will get some pics tonight and post.

[turbovanman²]

Yes, all pistons are egg shaped.

[Force Fed Mopar]

Okay, that's what I thought. Do the measurements I posted sound right? Any ideas why the 2 pistons got gouged up?

[Juggy]

Okay, that's what I thought. Do the measurements I posted sound right? Any ideas why the 2 pistons got gouged up?

excessive bore clearances!





measure all 4 pistons and see if they are the same
also measure the top diameter of the bore, AS WELL as the bottom. this will tell you if the bore has any taper.

im currently running a 2.5 with some blow by and i think there were some burrs on the rings as i got some scoring up and down the walls. my scrapes are all on the right hand side of the engine (back side, firewall side), just curious as to where your scoring is happening?

[MR. X]

Crappy oil. Clearance, heat.

[puppet]

Are they supposed to be elliptical? I know the stock ones are. I'm working on fixing Bozo's car, got the pistons out that have less than 5k miles on them, and #1 and #4 are done, the ring land area has bad gouging and the rings are stuck in the grooves. #2 and #3 pistons look like new, all 4 holes look ok. Used one of the good ones to check the piston clearance, I get .003 on the thrust side and .015 on the side-to-side surface in each bore. The piston measures 3.479 front to back and 3.464 side-to-side (if looking at it in the installed orientation).

I will get some pics tonight and post.

Doesn't sound like you're measuring at the skirt. Pistons are measured at the skirt for clearances.

The piston grows across the pin and that growth calculated by the maker. (depends on how much mass the pin bosses have) We (or machinists) just measure the skirt (thrust direction) for bore sizing. The skirt is the largest part of the piston, diameter wise. The crown expands at a different rate .. but again, that's calculated. Just check the skirt, the rest is automatic.

[puppet]

im currently running a 2.5 with some blow by and i think there were some burrs on the rings as i got some scoring up and down the walls. my scrapes are all on the right hand side of the engine (back side, firewall side),

Juggy, sounds like you have an oiling issue @ the skirts .. as in not enough.

[turbovanman²]

Scoring can also be caused by overheating, too rich or the classic one, too lean.

Juggy, didn't you mention you had a lean issue?

[Force Fed Mopar]

Doesn't sound like you're measuring at the skirt. Pistons are measured at the skirt for clearances.

The piston grows across the pin and that growth calculated by the maker. (depends on how much mass the pin bosses have) We (or machinists) just measure the skirt (thrust direction) for bore sizing. The skirt is the largest part of the piston, diameter wise. The crown expands at a different rate .. but again, that's calculated. Just check the skirt, the rest is automatic.

Well I'll check each pistons in it's respective bore then, to see if the scored ones are tighter. I used one of the good pistons to check all the bores, at the skirt they measure .003, and I slid it up and down in the bore and it seemed to be the same, resistance on the feeler gauge never changed.

I've never checked piston to bore clearance before, so I just took a bunch of measurements So I just need to check it at the skirt and that's it? I'll compare measurements on each piston tonight too. I've attached pics of them too.

[Juggy]

Scoring can also be caused by overheating, too rich or the classic one, too lean.

Juggy, didn't you mention you had a lean issue?

yes, last year, different motor....but this one im running is used and i dont know much about it, runs good tho lol.....

[turbovanman²]

Damn, you ran it lean or overheated it, if the clearance is ok, clean up the lands, new rings and your good to go.

[Mr overkill]

veryyyyyy hot

[MR. X]

Detonation is not your friend. Make sure you measure the ring groove. The crown of the piston may have lifted. Those are iffy to reuse imo.

[Juggy]

Damn, you ran it lean or overheated it, if the clearance is ok, clean up the lands, new rings and your good to go.

you forgot 2 add new pistons to that list
seriously i wouldnt be tossing that back in. looks just like the piston my buddy tore up when he tried to spray his car lol. is there any aluminum stuck to the bore?? does the ring come out without any issues or does it require some effort to get it out?

[Juggy]

you can clearly see in image #4 that the ring land is toast, i also see a spec of AL welded 2 the side of the piston....

do all 4 look like that or just the one?

[puppet]

Rob ... by the looks of them my guess would be not enough clearance. Doesn't Wiseco ask for .005-6" piston-wall? Those look worse than the cast SP's I pulled out of my block w/60,000 miles on 'em. That engine's burning oil pretty good eh?

You can take some muratic acid to the bores to dissolve the aluminum ... looks like they'll need it.

[Force Fed Mopar]

I'll see if I can get pics of the bores tonight, but they actually look pretty good, no scoring or gouging, can't even feel anything with my fingernail.

The pics are of #4 and #1 pistons, respectively. I will absolutely not be reusing them Bozo said it did overheat on him at least once when he blew a freeze plug. Probably the cause?

Puppet, the spec sheet that Chris sent w/ the pistons says .003 clearance It was smoking some yes, but not really bad, mostly puffed when you revved it.

[Force Fed Mopar]

I'll see if I can get pics of the bores tonight, but they actually look pretty good, no scoring or gouging, can't even feel anything with my fingernail.

The pics are of #4 and #1 pistons, respectively. I will absolutely not be reusing them Bozo said it did overheat on him at least once when he blew a freeze plug. Probably the cause?

Puppet, the spec sheet that Chris sent w/ the pistons says .003 clearance It was smoking some yes, but not really bad, mostly puffed when you revved it.

[puppet]

Yep ... was thinking of another piston maker's PTW. (still can't help but think .003" is tight). How much HP is Bozo making? Would Wiseco want another .0005" if he was over say 300hp or running (xx) boost levels? What I'm asking is if the .003" applies to N/A on up to 30psi pump gas?

Might very well be that the coolant issue caused this though. Hard to say but with that issue in the mix you're sort of guessing as to what happened.

At any rate ... your measurement should be across the skirt in-line with the pin bore. Right where, on some of your pic's, the piston was making wall contact. Any of the skirts cracked? Turn piston over and check to the left/right of the pin bosses.

[turbovanman²]

Yep ... was thinking of another piston maker's PTW. (still can't help but think .003" is tight). How much HP is Bozo making? Would Wiseco want another .0005" if he was over say 300hp or running (xx) boost levels? What I'm asking is if the .003" applies to N/A on up to 30psi pump gas?

Might very well be that the coolant issue caused this though. Hard to say but with that issue in the mix you're sort of guessing as to what happened.

At any rate ... your measurement should be across the skirt in-line with the pin bore. Right where, on some of your pic's, the piston was making wall contact. Any of the skirts cracked? Turn piston over and check to the left/right of the pin bosses.

Clearance is mostly set on how your going to abuse it, for a street car, you can set them tighter as LONG as you let it warm up. I set my old JE's and my last set of Ven's at .004, these JE's at .0035".