my machinist said that the the rods should not be pressed into the pistons because it could damage the pistons. he said the rods needed to be heated to assemble them. is this right or is it

 

if what he said is true, how hot should they be heated to?

 

He's right.

And it's not just hypereutectic pistons either, it's every press on piston.

The small end has to be heated a lot (I don't know the actual numbers) so the hole swells ever so slightly, then the pin is pressed through usually with a hyd. press. It's not something you can do at home.

AJ

 

yep it's all true. pressed pistons aren't truely pressed on. the small end of the rod is heated in a rod oven and there is even a fixture to hole and line up the pin, piston, and rod and every thing is sort of slid together before the rod cools.

 

hmmm well i was planning on doing what i needed to at home. all the pistons my dad has ever assembled, he just pressed them together and didnt apply any heat with no problems. what youre saying is i should take it somewhere and pay $$ to have it done? or is there someway you could heat them at home?

 

in the past, it had been done with a standard press. But, you much more likely to crack a piston (and you might not know until startup). Costs about 40bucks to do a set of 8.

 

Wish I knew this a couple months ago. We just pressed mine in with a press. If it cracks a piston how long does it take to develope a problem?

 

It can be done with a press without problems. Used to do that all the time at work. We also heated some, and had some special fixtures for other pistons that required them.

 

thanks for the input guys. we ended up just pressing them without heat and everything went fine. i was a little scared though :lala:

 

couldnt you heat the rod ends and put the pins in the freezer over night. The rods would expand and the pins would shrink some what. Not much, but enough to help. Just a thought.

 

if you want to shrink the pins hoes them down with some r134 at 5 bucks a can. lot colder and lot faster. way back when we didn't know r12 was bad for the ozone we'd soak bushings with a 30 pound can to get then in some off road equipment i worked on.

 

Good Idea, I had done the freezer thing with king pins before, but had not thought about using r134. thanks for the tip.

 

Pressing them without heating the rod end won't crack the piston; but what it will do, is to destroy the nice shiny finish they put on the pin, that forms the bearing that the piston itself rides on, by scratching the h*** out of it while you're cramming it through there. It's a real good way to create premature pin bore wear, leading to piston slap.