4.0 connectin rod modification question.

[nicpaige]

I have seen a few mentions about modifying the piston end of the 4.0 rod for the KB944 pistons for clearance? Is this true and is it simply a matter of grinding off the casting bumps to make the end more uniform and round?

[Cheromaniac]

I have seen a few mentions about modifying the piston end of the 4.0 rod for the KB944 pistons for clearance. Is this true and is it simply a matter of grinding off the casting bumps to make the end more uniform and round?

Yes, and yes. Just grind off the squared off ends and make them round like the rest of the small end.

[nicpaige]

Okay cool, thanks.

[Russ Pottenger]

I have noticed that they've started making some changes to the underside of the piston
Allowing for more clearance.
Whenever I match balance rods I knock off the corners off first. That being said I believe they have addressed this problem
In their latest configuration.

[nicpaige]

I took the advice and turned out a jig on the lathe to hold the small end of the rod while machining it on a proto-trak. Worked like a charm. Also mad a press jig to drive the wrist pins out of the rods with a hydraulic press. Everything worked out great. Set the crank up on the mill and took 10mm off the snout on the 4.2 crank. Time to load up the crank, block, rods and head to the machine shop. I'm guessing I should get my ARP main and rod bolts in before I drop the block off right?

[SilverXJ]

Yes, you need the ARP bolts before the rods can be resized.

[IH 392]

I made a "false" wrist pin to check the clearance on my KB944's, IIRC? only one had any contact with the piston, balancing took care of that.
If you go straight to grinding off the balance pad on the small end, you may be screwed when it comes to the final balance?