rod issue and how can in fix it?

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rod issue and how can in fix it?

Post  Rickytx630 on July 24th 2017, 10:25 am

over the winter i have decided to park the bracket car and go through front to back. made some changed to the motor and now i have a few issues, its still the same cubic inches (4.440 bore X 4.150 stroke. the plan was to change the heads from the A429cj to the kaase p51. instead of notching the pistons for the valve relief. i decided to buy new rods and pistons and have the motor rebalanced. now heres what im having problems with, crank goes in, torqued, spins freely, clearances are good. put 7 rods and pistons in and its nicely. i go to put #1 in it and it locks up, cant rotate it at all. pull all the pistons out and try number one by its self and same thing happens, pull that out put an old piston and rod in it and it spins perfectly ( with #1 by its self and the other 7.) the new pistons are diamond, and the old ones are from JE, so i know the weight is different but the rods are the same brand and size, is this a simple fix? i know this is stupid but can i just swap rod off the old pistons and go from there or do i have to have the rod end machined and the motor rebalanced? can they just fix the rod end and i go from there? really dont have the time to pull this all apart and send it out again, but if i have to i will. i do know that ill be looking for a new machinist thats for sure.

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Re: rod issue and how can in fix it?

Post  away on July 24th 2017, 10:54 am

Sounds to me like one of the rods was put on the piston backwards and the chamfer of the rod is now on the wrong side so when you torque the rod down it bites into the fillet of the crank journal.
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Re: rod issue and how can in fix it?

Post  69F100 on July 24th 2017, 1:00 pm

Try putting the piston in upside down if it turns over good with the piston in upside down then the rod is on wrong
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Re: rod issue and how can in fix it?

Post  BBFTorino on July 25th 2017, 12:32 am

I'd go with what 'Away' says. The rod is on backwards and its clamping down on the side of the journal where the fillet radius is.
Also, may sound dumb, but check to see that you don't have a wrong size bearing on there too.

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