JE pistons with press fit on stock rods? Anyone have any sort of fit issues ?

[Mike T]

Couldn't find a picture online so here's a paint shop rendering.

 

[Tim Cucci]

Nice rig. No pressure on the piston.
I got no choice but to take mine apart. I've checked everything. I've taken 3 and 4 in and out , magnifying glass, feeler gauges , mirrors, retorquing everything. The most clearance on any rod is .020. Some are tighter and some barely rubat the very top of the stroke.
Thanks for the help.

 

[earlbrown]

Like Earl said you need a special tool to press the pistons back off of the rod. My machinist was not thrilled about doing this so he loaned me the tool.
Got them apart without hurting the piston but was not thrilled about putting that much pressure on a brand new piston.

The tool actually supports the rod so the pin can be pressed through but it take a lot of patience or you'll damage the piston.


Pins had a few scuffs so I replaced them along with the K1 rods.

that is one nice ass machinist. That Kent Moore tool is NOT cheep. Each of those plates cost a freakin fortune!

I hope you didn't toss those rods as they are still good. Hell, even if you don't trust a pressed finish they can always be honed out to a press fit.

 

[Tim Cucci]

The only way to know is to mock up the engine and check. The bad part is if you need to do some machining, the rod has to be removed in a press with a special tool that doesn't load the piston. (the reassembled after machining)


My 2618 pistons call for .040" per side and with a wide rod it's pretty tight.

Earl have you seen this problem before with stock rods rubbing the side of the pin boss at the small end? Seems like others would have run across this problem before.

 

[earlbrown]

Not with stock rods, I haven't. An aftermarket rod with a wider little end coupled with an off-center engine might have to have some work done. I've never built an engine like that before.

 

[Tim Cucci]

Not with stock rods, I haven't. An aftermarket rod with a wider little end coupled with an off-center engine might have to have some work done. I've never built an engine like that before.

Took my pistons and rods to my machinist and showed him the up close photos. He is a reputable machinist in our area and he seems to think that this issue has more than likely been overlooked and probably caused some issues before without discovery.
He is going to mill some clearance inside the pin boss on the tight side and balance again.
In my opinion I think JE should not reference this piston 131556 for direct Buick GN replacement unless they reference additional machining to be done. This $300 dollar set of pistons is costing me a ton of money. I could have bought a new set in another brand for what this is costing. Live and learn! Kinda Pissed Now.

 

[Mike T]

He is a reputable machinist in our area and he seems to think that this issue has more than likely been overlooked and probably caused some issues before without discovery.

Totally agree that others have had this issue and not caught it......on the other hand the rods probably created their own clearance after some run time.

 

[Tim Cucci]

I do agree about the rods creating clearance and that thought did run thru my mind but I just couldn't do it.
Thanks

 

[earlbrown]

That's called hotrodding. Anything outside of a factory OEM 'assembly' is not a 'built' engine.

Building custom engines requires extra attention to detail and effort. That's part of what makes custom builds so cool. Not everybody can do it. in JE's defense, they have no idea how wide your little end is, if you're on-center or off-center, etc...

I'm pretty sure their piston they're selling for V6 Buicks is a verrrrry old design since they guy that designed them has been long gone from JE. When that print was made there might not have been such a thing as off-center.