Hey Guys! I need a little advice.
I'm rebuilding a 390 (new crank, mild cam, .0030 bore, new pistons, valve job), and I'm ready to put pistons on the rods. When I checked the wrist-pins in the rods, I get a little rocking motion out of a couple of them. There is no slack in line with the rod (up and down), but if I wiggle it in a rocking motion, I can feel some slack.
It's been a long time since I worked as a mechanic, and I'd just like to hear from someone else as to what you think.
Thanks a lot! I always appreciate the advice I get here!
Brett

 

Mine went together pretty darn snug. Lay it on a table top piston down and support the piston. Push the rod in the direction of the wristpin ends. If it has play (not sliding but rocking)..not good . May need to have the rod bushed and reamed..if all else fails run it by a local machine shop for review.

 

I'd certainly get the small-end bushings checked out, and possibly replaced and honed out.

Can you tell if the rocking sensation comes from play between the bushing and the pin, or the pin and the piston?

Either way, sounds like the ends of the small-end bushing are worn out slightly.

Figure it this way, the piston will wiggle in the bore in the same way as that rocking motion.

 

Thanks Guys. You've confirmed what I should have already known. Rods are going to the machine shop today. Thanks, Brett