3400 bent wrist pin [Archive] - GrandAmGT.com Forum


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06-12-2010, 04:27 PM
I have a 97 3400 from a transport van in my 2001 cavalier, I accidently hit 30 psi last summer and bent a rod. I replaced the rod and everything seemed fine until last week I drove the car into the garage and stripped down the motor for another year of abuse. I have taken my motor apart and found out that I have a bent wrist pin and I am using wiseco 9:1 pistons from the group purchase a couple of years ago and I was wondering if you knew if it is possible to machine out the piston wrist pin hole to .927 same as the sbc rod wrist pins use and use wrist pins & H beam rods from a sbc. I am not sure if the circlips will have enough room to grab properlyand I am not sure what other problems I will encounter. Please help.

06-12-2010, 04:53 PM
im not exactly sure what the 3400 size hole is, but i dont see that being a problem. as for sbc rods, the have to be notched to accept 3400 bearings, but i think thats it. that would be a solid setup. others will chime in

06-12-2010, 05:23 PM
I am using stock rods which have size of .912 and I am trying to salvage my pistons and the only way to do so is to have the hole machined as It is out of round whatever the pin is bent. I am hoping .016 would do it.

06-13-2010, 08:18 AM
You can use SBC rods with small journal ends. They have to be notched for the 3400 rod bearings, and they need to be narrowed slightly to fit on the 3400 crank journal. That's it, just some minor machining. As for the pistons, I haven't seen them and don't know their dimensions so I can't really say, but I would imagine as long as there is enough metal around the pin hole that making it slightly larger won't weaken it too much, and as long as there is clearance under the piston for the larger SBC rod, then it should work.

06-13-2010, 08:44 AM
THe piston are wiseco forged from a group purchase a couple of years ago, my main concern is that there wont be enough depth to the spiral lock grove to hold the sprial locks in place of I remove .008 from it on each side by opening the wrist pin to .927 from its current .912.

2001 Cavalier 12.2 @ 123.66 mph t3/t4 @ 15 psi THis years upgrades T70 , Custom intake manifold, 70 mm tb and also meth injection all waiting to go on after my piston ordeal is fixed. Should finally hit 11's, if not maybe 130 mph.

06-13-2010, 09:51 AM
vroom vroom on the cavi, hope it works out for you