best solution for a rod knock

[e30m20TurbO7]

Whats the best way of tackling a rebuilt motor with a rod knock on one cylinder, yes i know remove the crank and send it in to have it checked out. should i remove the problem piston too? because i would really like to keep the top end intact with the block , i also have a spare eta bottom end already dismantled. still dont know how bad the crank is on the car with the knock , but as soon as the knock was discovered the car has been sitting and it only knocks under load. would the crank have to be cut? I did plasti gauge all the bearings before , all the mains were in check. would i be able to re-use the mains if they are not damaged , not that i want too. also could i have created a rod knock by driving to hard on a fresh bearing motor?
need some advice

[jlevie]

How many miles on the engine? The bearings all need to replaced and the correct "color" of bearings used based on the crank journal dimensions. You will have to get the crank out to check condition and wear. The top end needs to come off and the cylinder bores checked to see if they are past the wear limit, especially if the engine has over 150k. Since a bearing has failed, the block really needs to be torn down all way and throughly cleaned (but not hot tanked) to get rid of loose bearing metal.

If the cylinder bores are okay and crank is okay, the cylinders need to be cross hatch honed, new rings (properly gapped), new bearings, and a new oil pump used. You might as well have the valves ground, new seals installed, and possibly new guides unless that has recently been done. The head needs to have at a minimal (~0.005) surfacing cut.

The cylinder bores are worn past the wear limit, just get a low mileage replacement engine. That will be cheaper than a rebore and new pistons.

Plastigauge is good for a sanity check, but it isn't reliable or accurate enough to ensure proper clearance and it can't check for out of round journals.

This isn't the easy or cheapest solution, but you did ask for the best solution.

My guess that the rod bearing failed from improper clearance or a bad journal or a problem with the rod bolts. You did use new ones, right?

[e30m20TurbO7]

I used all new correct sized rod bolts. the motor had less than 1000 miles since full rebuild. I honed the block when i rebuilt it the bores were perfect at the time , i had the head milled as well as new guides and a 3angle valve job, i don't see if being crucial to buy a new oil pump since its machanically driven and the main part that fails is the pump shaft, is what i was told , just properly go through the it all and lube up the shaft that spins it. as well as check the gears. what do you meen by "color" of bearings. if i have another crank should i get them both checked out to see which one is a better candidate .
does the head need to me milled again since i just had it milled , also since im going to be tearing down the block to a bare block again im most likely gonna oring it .
so im pulling the motor tomorrow . i will post some pics on this thread of the tear down . to show you what im working with
thanks for you're help jim , if you have any more advice with the information i gave you , it would be much appreciated

How many miles on the engine? The bearings all need to replaced and the correct "color" of bearings used based on the crank journal dimensions. You will have to get the crank out to check condition and wear. The top end needs to come off and the cylinder bores checked to see if they are past the wear limit, especially if the engine has over 150k. Since a bearing has failed, the block really needs to be torn down all way and throughly cleaned (but not hot tanked) to get rid of loose bearing metal.

If the cylinder bores are okay and crank is okay, the cylinders need to be cross hatch honed, new rings (properly gapped), new bearings, and a new oil pump used. You might as well have the valves ground, new seals installed, and possibly new guides unless that has recently been done. The head needs to have at a minimal (~0.005) surfacing cut.

The cylinder bores are worn past the wear limit, just get a low mileage replacement engine. That will be cheaper than a rebore and new pistons.

Plastigauge is good for a sanity check, but it isn't reliable or accurate enough to ensure proper clearance and it can't check for out of round journals.

This isn't the easy or cheapest solution, but you did ask for the best solution.

My guess that the rod bearing failed from improper clearance or a bad journal or a problem with the rod bolts. You did use new ones, right?

[e30m20TurbO7]