M-Tuned rods small end bores need honing
 

From the rods group buy thread:

I'm trying stock piston pins on 'em now. While it's very easy to get em on the stock rods, it is difficult to push them onto the M-Tuned rods. As I start to push them on, it feels like they're galling.

Anyone else have this problem with stock piston pins?

Looks like I need to have them honed - workshop manual says the difference in bores between the rod and the pin should be 0.0004 ~ 0.0011.

Would it be OK to take just *one* piston pin to a machine shop and have the 4 rods honed?

I had the same issue.

I would take each wrist pin to the machine shop with each rod and have them check clearances on every one. Just have the shop label each so they don't get mized up. IIRC two of my rods needed honing and two did not.

FWIW this was with 8.6:1 supertech pistons and supplied pins.

This is common fair with any motor.

Thanks.

Snowboarder, was the variance in the wrist pins or the rods?

Is there a chance the big ends need machining too?

My Belfab (same?) needed honing too with Supertech pistons (from Belfab too, go figure)

My Eagle rods needed to be honed also.
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Its standard to get the big and small ends honed if they don't mic out. Anyone not mic'ing before installing should expect that they don't have correct clearance (although they might), and that it could kill your motor.

my builder measured the big ends of my belfab rods to be 1/1,000 out of round. His standard is for them to be less than or equal to 2/10,000 out of round. They were five times worse than he was comfortable installing, so they were machined to within tolerance. I understand this is common with the chinese forged and US Honed rods.

It happens - thats why I paid a professional to rebuild the engine.

winner!!!!

To be honest i cant remember, but i do remember having a piston or two honed for the wrist pin as well.

here, let me show you what happens when you ignore this......http://lh4.ggpht.com/_LCqV-xbgfGg/Sy...0/IMG_0038.JPG

+1 on the eagles, i had to hone mine a wee bit, same with my biddies built 323 GTX. I believe the reason behind this is due to different piston companies making different wrist pin sizes, so rod companies leave the small end slightly smaller so as to accommodate these sizes. (ie:eagle rods with wiseco pistons, mtuned rods with ross pistons ect ect...)The reason the big ends dont need honing is because they are made to fit on one specific crank.

it all makes sense now, fuck my life for over looking this before

I thought your oil pump busted a plug and squirted oil into the engine bay?

What piston wrist pin clearance does ETD recommend?