engine pinching.... anyone know?
 

hi i am in need for more compression in my .21 engine and the hobby shop that does pinching does it to the piston not the sleeve ...what is the best way by expanding the top of the piston or pinching the sleeve?
i am guessing the sleeve way would last longer but what actually lasts longer the piston or sleeve waY?

Hum..........I have never heard of anybody working with the piston. How do you expand the piston?

I heard a while back that people were using a blunt punch under the piston to get it to mushroom slightly but this method resulted in a broken piston more often than not. It was done before there were good processes to resize the sleeve. I would send your piston and sleeve to OS Rocket or Ray-A-Racing. They both have high quality tooling and presses that do it accurately. Ray A Racing also cleans up the piston a sleeve (polishing) as part of their service.

I will let you guys know how the Rayaracing works out. I just sent a piston and sleeve into them. I am hoping for good results

David I remember the process you are talking about, that was long before my time! LOL I thought Downunder was refering to expanding the Dia. of the piston which seems nutty but you never know. You can't go wrong with the two names listed, both are first class.

I had ray do two of my engines with great results.

Dont let them mess with the piston, just the sleeve pinch. I would not go back to them after that reply. :weird:

so anybody experience with the pinch sleeve..?? whats the performance..do it perform like new one..do u have to repeat the break-in process.. can it last long..how many time can pinch the same sleeve..

i have try pinching my sleeve. it make the sleeve getting oval.. the piston is tight in the sleeve but no good compression.. i just like using combination used piston/sleeve from different engine..ex: sts sleeve + hyper 8 port piston.. and the result more better performance then the pinch formula..

is raya racing in us? same with os rocket?
if so would it cost much to send to them i am in Australia.

engine life after pinch
 

ok i found out both are in usa just one other thing how long would i expect my engine life to be after the sleeve pinch is done? few galons? or just litres?
i sent mail to both rayaracing and osrocket the biggest cost will be postage so well see how it pans out.

You should be able to get in a few more gallons. You will probably have to go through a small breakin with the pinched sleeve, nothing like when new. I would suggest you do this with the same rod that is in there now and when you are done with breakin replace the rod. The rod is probably already worn and running a engine with a fresh pinch is not going to help it any. This way there shouldn't be any stress on the new rod.

when breakin new engine, seem the conrod, crank shaft, piston pin and bearing got very hard stress from the very tight piston and for sure that part in the new engine will wore out a little.. is it..
so is it good idea breakin new engine like this.. take out the new engine piston/sleeve only and breakin it in old engine..when have finish breakin period, put back the piston/sleeve to the new engine. so ur new engine got totally no wore out part inside the engine..

if you want a pinch i can do it for you. just pay for postage. i have done it for my friends.

disclaimer: all care but no responsibility taken

I have a few pinchers myself and have probly pinched 2 or 3 dozen engines . If you get a good quality pincher it works out great . I get about another 4-5 gallons per pinch . I`ve only pinched the same engine twice and wouldn`t go beyond that . These myths of cheap ways and hose clamps to pinch are a waste as you will oval the sleeve . As long as the rod is still in good shape it`s safe to pinch . But do your first few pinches on some junk engines as it can be easy to overpinch .