Pistons won’t come out

[gzig5]

So can someone enlighten me as to why the oil rings have a hard time getting over a ridge but the top two don’t? I had to essentially eliminate the ridge or the piston would not come out

 

[gzig5]

And now;
because you didn't ridge-ream the block ............... and made a mess; you are looking at .060 overbore? instead of .040; Is that right? I mean jus asking for a friend.

Either way it’s going in the bin. It would need at least 20 over to clean up from the ridge and I have no use for a 273. If someone else can use it great and I’ll take care of that in another thread. I’m pretty sure that my method of removing the pistons didn’t open the bores up much over where they would have with the reamer because I had to do it multiple times to get them to come out. I took light cuts

 

[AJ/FormS]

So can someone enlighten me as to why the oil rings have a hard time getting over a ridge but the top two don’t? I had to essentially eliminate the ridge or the piston would not come out

Well, look at them. They are practically knife-edged, and not cast like other two, and have a big ol' spring pushing them against the cylinder walls. They get stuck in the worn part where the top ring stops and under the sharp metal step politely called, a ridge. To the oil ring, that ridge is practically a solid wall. Whereas the cast rings just bounce up and over.
Most of the wear in a cylinder, occurs in that last inch or less, cuz that is where all the action is, and that is where the piston slows down, stops, and reverses direction, spending a comparatively long time there, half of which is under pressure from above, that is desperately trying to rock it, on the wrist-pin.

 

[RustyRatRod]

Tap them hard enough so those pistons land at my front door!
Yeah just sand gently on top of bore.

Now that's funny right there I don't care who you are. lol

 

[gzig5]

Or maybe you'd rather have a 340..... lol. But not giving that away...

Already have two 340's, don't need another. Thanks. I saved this 273 short block which had been sitting outside for fifteen years at least, from the scrapper and am just trying to save some parts others may be able to use. The crank and rods may or may not live again in the second 340 block I have.

 

[Inertia]

Well the pistons could have the ring "lands" broken from trying to get past the ridge.
Not much to save .

 

[4spdragtop]

They would have a soft landing in my back yard

Now that's funny right there I don't care who you are. lol

 

[RustyRatRod]

They would have a soft landing in my back yard


View attachment 1715861363

Hell, you'd lose um. Least till the SprAng.

 

[pishta]

Its a crude instrument: a chisel looking carbide blade on a 3 prong expanding spider and you turn it with a wrench. The turning forces the spider and blade out into the ridge and it just scrapes the ridge away. I thought it would be a little more civilized but it gets the job done. Dont mess with ridges, I broke a ring land on an unobtanium out of production MP stroker piston and through the power of the internet and a little luck, I got one sent from a guy that had an NOS set in the wrong size.

 

[pishta]

you can have all the scrapes in the top of the cylinder but if its over the rings, its not going to kill anything. Look where the rings sit at TDC and if the scraped ridge is over that (itll be right there) , its not going to affect the ring pack dramatically if its a flush trim with the cylinder. Its still gonna be a bit larger OD but the ring should survive.

 

[MOPAROFFICIAL]

Ridge reamer spares the ring lands of the pistons.
Forcing them through usually works...but you're beating g the rings against the lands and that leads to sloppy ring movements in the piston and more chance for a less than square fit/seal to the bore. Many aren't ridged and the pistons come right out...some you hammer out and the rings break...ring lands hammered...we just throw them away in leu of new ones.

 

[MOPAROFFICIAL]

Stone hone the top/ridge.
Regardless....it will need hone to size and that cant be done at home and end up round...it will be an expanding oval and blow smoke if run like that. Dont mind me if I sometimes sound like captain obvious...