I got my pistons and pins today. When I went to test fit the pistons/pins onto my rods, the pins were TIGHT . I got my micromiters out and found that the piston pin is exactly 0.927" while the small end of my rods are 0.926". Looks like I will need them honed a tad to make them fit. Any idea how much this will run me?

more money needed.....its always more money needed

 

Should only run you about $20 or so. Only takes a machine shop about 15 minutes to do them. Your gonna want them to hone your clearance to .0008-.001". Make sure to take at least two wrist pins with you to the machine shop. Some shops use them as there gauge to insure you are getting what you need. Good luck

 

thanks Chris

 

You need to be able to measure to .0001, which is tough with a .001 reading mic and expanding hole gages. Don't even think of using a caliper.

Assuming the rods are bronze bushed, thoroughly clean both the rod ends and the pins with solvent or kerosene (not gasoline, please), blow them dry, oil the pins with motor oil and try to assemble them VERY carefully. Often they get dust on them during shipping or storage. If they are still tight, and the piston won't rock under it's own weight go to a precision engine or machine shop familiar with engine building. First you might disassemble the rod, wash and dry it, and look in the bushing to see if you can find rub marks. If there is a cross hatch, the bushing was honed. If there is no cross hatch it was probably diamond bored. Either way is good.

Of course if the rods do not have bronze bushings in the small end they are 'press fit' rods and all this is academic.

If you are looking for .0008 clearance (ask the rod manufacturer what he wants...max and min), find a shop with a bore gage that accurately reads to 50 millionths or .00005. Sunnen makes some good ones. Have them measure the pins and rods to see what clearance you have.

They need to hone the bushings very straight, and probably only remove a few "tenths" (.0001). It's easy to screw up.

In my experience, pins are made very accurately (within .0002 usually) and good rods I've seen are within .0004 on the bores. If you have to hone, take everything and have them check all the pins and all the rods.

Be sure it's broken before you try to fix it!

My $.02

 

hmmm....I'll go try that

 

well thanks all. it turned out that there must have been some burs/dust/something on the pins/rod ends because after I cleaned and re-oiled them, they just sliped right in. Some needed a little more "push" (put the rod on the desk and pushed with my thum) but they all went in and are now moving free. this day is going good.

 

They are a tight fit. Everything has to be lined up perfect for them to slip in.

 

yep....found that out. if I cocked them ANY they would not go in. its all good to go now

 

Cool!

 

Ck the big end housing size also then ck with bearings installed be sure you have desired clearance just cause there new does'nt mean there right. I've had to fix at least 2 or more rods out of a set every time.

 

the pins slide freely (not LOOSE...but free) in the rods. I have not checked the big end but I will be having the machine shop will do that when they ballance the setup