[antique69lemans]

Originally Posted by gearbanger

Were the upper rod bearings cupped to the point they wouldn't stay in the rod. If so, I would say definitely detonation. I went through several engines back before I knew about detonation. Engines all ran good and you could not hear any pinging or rattling. But after a few thousand miles the oil pressure would go away and eventually would start knocking.

Pull it apart and all the bearing would be down to the copper. That was back when I was trying to run 670s on a 406 with pump gas. Not gonna work.

Bearing inserts being loose AFTER meltdown is common. They are deformed under the extreme heat and lose their shape. The rod big end is suspect from the heat. Even if they were perfect before, the rods will probably be "egged" and cause improper clearances with new inserts. I have seen oil starvation cause rods and blocks to blacken from the heat and burnt oil. I would personally consider another set of rods in the next build.

[68grandprix]

A couple of the lowers were cupped. I heard the engine rattling/knocking as I slowed from the interstate and the oil pressure was considerably lower than it had been. Most of the bearings look the same. Oil pressure was 75-80 psi at startup, around 60psi when warmed up and running down the road at 2000-3000rpm. Oil filter is an AC Pf24. The rods are the PPR 4140(cheaper forged). The engine ran 190degrees all the time(except went to 210 one time during extended idling). Tangs on rods are facing in. The short block was delivered complete, I assembled the top end. The rods shouldn't have been resized, they were new.
I do plan on completely tearing down the engine and getting it cleaned out. The heads are 6X-4, with the combustion chambers opened up by me as suggested in HTBHP Pontiac V8s. Also a valve job. 455+.040", I knew I'd be close on 91, but the motor ran the same on 91 as it did on 110(as far as I could tell). The piston tops were also polished with all sharp edges smoothed. Jim

[Ken K]

If the crank was standard and you just had it polished then there should not be any problems with clearence. I had a machine shop check a set of those rods, I was told the big end was right where they liked it.

[Ken K]

Riffle brush the oil passages. 1500 miles should not be enough time to get them dirty. If they were cleaned then you should not pull any gunk out of them. Dirty ones can be just like tar.

[old66tiger]

I would have all of the big ends checked by the machine shop to make sure that they are all the same size. Then, have the crank checked to make sure that there is consistency. My guess is that it was too tight - borderline. The bearings did not look rough and the picture of the crank looks nice and clean. Should clean up well with some new bearings.

[chevymad]

Are all the bearing halves marked standard? On a recent build I had half of my main bearings std the other half 0.010. Came out of the same box, in sealed shrink wrap. I looked saw 0.010 and installed. Then wondered why I had no oil pressure. First time I ever put one together without at least plastigauging too! I was sure of the machine work because it was a running motor.. never thought the bearing shells themselves would be a problem.

[72blackbird]

Jim,
6x-4's on a .040 455 make about 9.3-9.4:1, a bit close for 91 octane, even if you opened up the chambers a little- a chamber volume check will tell you for sure. I've used the PPR 5140 rods on other builds an they're usually dead on, but it's not a bad idea to have them rechecked for roundness after what happened.

Have your machinist mic the rod and main caps torqued to spec and crank journals after everything is cleaned up. I'd shoot for a .0018-.002 oil clearance on both the rods and mains- that should give you both good oil pressure and bearing protection.

Geno

[Z Code 400]

I've had a few sets of brand new rods lately that were too tight and had to be honed. Check everything twice, even the obvious stuff...Robert

[2manyponchos]

Were the mains and cam bearings ok? If not, might have been a good idea to do an oil sample analysis. Have seen this on an engine that had coolant in the oil, but all bearings were affected.

[68grandprix]

Here are a few more pics. Pistons, bores, chambers looked good(may have been running a little rich) but one rod journal and rod are discolored. Does this mean I need a new crank and rod(s)? I haven't checked the mains yet. I can't get the damn damper off and I'm waiting for a puller(mine was borrowed and never returned). The pistons are also about .030" down in the hole according to my cheap machinist's dial gauge. If I remember right the online calcs said I would be at about 9.6:1 compression. Jim

[68grandprix]

pics

[Ken K]

Is the discolored rod and journal toward the front of the engine?

[AG]

By the looks of the chambers, you have an oil blow-by issue also.

[68grandprix]

It was the #4 rod. Jim

[webfoot]

FWIW I have those cheaper forged rods and had to get the big ends resized. The machinist said they were hourglass shaped.

[Ken K]

Now you are starting to scare me. I have a set of those rods and they checked out and the engine is still running. The reason I am scared, that is the second engine I have seen pictures of using those rods that had bearing problems. The other was a 400.

[68grandprix]

The mains look like they would have been ok, but some are now grooved(I assume because of rod bearing material). The outer sides of the thrust bearing are copper-colored, is this normal? Jim

[Ken K]

The copper color on the thrust bearing is normal, that is how brand new ones look. What brand of bearings did you use?

[Ken K]

This is the bottom end on a 400.

[rod cole]

The discolored one indicates it was to tight[most likely cause] or starved for oil. Poor clearance checking as a fyi I receive a new set of FM bearings and they were half .010 and .020 right out of the box.