Very simple piston question

[Puller]

Putting in forged pistons, got the old conrod/piston assemblies out... how do you get the pins out so i can seperate the rods and pistons, i need to use the rods but not the old pistons. i honestly just don't know. brute force didn't seem to work. just let me know.

 

[Defiant]

They're press-fit, they come out by being pressed. Preferably, in a ....wait for it.... press. The specified pressure at room temperature is 1½ to two tons. Probably worth the $20 the machine shop will want to do it for you.

 

[-GSX-Falcon]

...wait for it....press

I was on the edge of my seat :laugh:

 

[Puller]

Also, how do you tell if the pins are floating or not, as far as the forged pistons go. so far the project has gone fine excluding this trivial bullshit. I read or maybe misread that if the pins of the forged pistons are floating the rods have to be machined...shed some light.

 

[Defiant]

Well, the devil's in the details. Maybe more with motors and the like than most other things we deal with.

So far as I understand, most aftermarket pistons are floating-pin designs. Usually, you'll have circlips in the pistons that hold them in place. Racers used to use Teflon buttons, I don't know if that's still going on or not.

For one thing, floating gudgeon pins are easier to work on.

It's a choice made by the piston manufacturer.

 

[Puller]

most definately. i must be missing something... what problems may be forseen in using floating pistons with 1g rods i haven't gotten my stock rods back yet so i could likely answer my own question then but i'd like to know in advance. "Do not use spiro lox [pin retainer] if pin is press fit." -Wiseco...Are they saying, you are able to utilize both press fit or floating design with their pistons but don't use spirolox if you choose press fit? or are they saying basically you can't use 1g rods because they are meant to be press fit? great thanks.

 

[NOSNUSE]

Basically with press fit pistons the wrist pin does not move around in the small end of the rod with full floating the wrist pin moves back and forth(basically floating on a layer of oil) in the rod, that's why you need the sprial locks on the ends of the pistons to keep the pins from coming out. Full floating are really useful if you do alot of rebuilds on the same motor because you don't have to keep sending them to the machine shop to have the pins removed, also press fit pins they heat the small end of the rod up to expand the hole and press the pin in and let it cool which cause the hole to shrink and hold the pin in place, if you where to make your factory rods full floating you need to make sure that the pin hole diameter is the right size to prevent any type of rubbing or contact with the piston, I have heard that it is not a good idea to use factory rod with full floating pistons because they where not designed for that type of piston, also make sure that there is an oil hole drilled in the top of the small end of the rod to allow oil to get to the pin if you go full floating. Hope this is of some use to you, later.

 

[Puller]

ok thanks much appreciated, would you think that eagle rods are set up for floating?

 

[NOSNUSE]

Most after market rods are just make sure when you order them that they are made for full floating pistons. Good luck.

 

[Puller]

check the trader for brand new pistons for trade and/or cahs/paypal. i would have done more research but i was in a rush. word of advice, slow and steady wins the [motor building] race.