[RPM]

I have a 428 that as long as I have owned it, liked to chew up bearings. The last set lasted a little over 500 miles, previous set lasted 3000 miles. What I have been finding is the rods down to the copper and the mains are scored and shiny, but not into the copper. Oil pump is a Melling 60 psi., main clearance is .002 and rods are at .0025.
What I am doing this time around is leaving the windage tray off, running fully grooved mains with the feed hole opened up, 80 psi pump, restrictors to the lifters (solids) and using a baffeled oil pan. Measuring the mains showed the last line hone produced an egg-shaped hole so that was re-done. Even though the main clearance was .002 at 12:00 and 6:00, it was tight at 3:00 and 9:00 and at 45 degrees from horizontal and vertical. Maybe this was starving my rods?

[RPM]

I have a 428 that as long as I have owned it, liked to chew up bearings. The last set lasted a little over 500 miles, previous set lasted 3000 miles. What I have been finding is the rods down to the copper and the mains are scored and shiny, but not into the copper. Oil pump is a Melling 60 psi., main clearance is .002 and rods are at .0025.
What I am doing this time around is leaving the windage tray off, running fully grooved mains with the feed hole opened up, 80 psi pump, restrictors to the lifters (solids) and using a baffeled oil pan. Measuring the mains showed the last line hone produced an egg-shaped hole so that was re-done. Even though the main clearance was .002 at 12:00 and 6:00, it was tight at 3:00 and 9:00 and at 45 degrees from horizontal and vertical. Maybe this was starving my rods?

[Blackcat]

Have you considered the possibilty of detonation? It will pound the bearings down to the copper in a very short time. With forged pistons and stock rods. The bearings will go and the rods will (sometimes) go out of round. If the rods aren't resized properly. The bearings will go in a short time. Been there done It!

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Mr. Z

[All4Fun]

May sound stupid, But I would check to see if the crank is bent. That might explain the loose/tight. When your talking thousands of an inch clearance it won't take much.
Just a thought because I just started a rebuild and mine was tweaked a little . Had to have it straightened. I was lucky and found out while it was being ground.

[RPM]

Thanks for the replies. At this point any and all causes I can think of have been considered. Detonation damage as far as I know would show up on the rod bearings as the piston side more worn than the cap side. My rod bearings showed even wear on both halves and looked like a momentary oil starvation. Rods are Eagles and the big ends measured out fine within tolerances, in fact right in the middle of the range. Also there was no evidence of the rods getting hot and the crank journals were not scored. Rod bearings are King brand and mains are Celvite 77. The crank was checked and found not to be bent. The assembly was balanced and I have a new stock harmonic balancer, that was balanced with the crank. Oil passages in the block were clear also. Cr is in the low nines and I have never *heard* detonation. I know that that does not mean it wasn't happening but besides the bearing damage which may or may not be detonation related there are no signs of det damage anywhere else.

[RPM]

Bearings going again. Just may be the best answer would be to open up the chambers of my 670s to lower cr. If done right this will also help with breathing. I figure I need about 7-8 cc more to put me at 9.0:1. Any suggestions on opening the chambers?

[PONTIAC DUDE]

Are you running a remote oil filter? And if so any 90 degree elbows? Check alignment of the oil passages in the back of the block casting. Elongate the oil hole in the main bearing to flow more oil. Grind an oil slot extension in the lower half of ther main bearing to align with the half groove in the top half. Later, http://PontiacPower.cc

[All4Fun]

Might check your rod side clearance. If it is excessive this would cause a slight loss in oil pressure. Might explain why your rods are going out before the mains. Just something you might check while you have it down. Hope this helps.

John