Bearing diagnosis

[Dan Timberlake]

Got pix of the upper main inserts and lower rod bearings?
Got pix of the spark plugs and piston tops>

All the "wall-to-wall wiping" on the lower mains suggests periods of inadequate low oil flow to me.
Do much street fighting or strip time?

[BLstangin]

I had a dirt track engine eat a timing chain like this once. The fuel pickup got sucked against the side of the fuel cell and motor ran lean and lost power and got hot, but of course he was leading so no sense in pulling in. He won the race and when we got into tech we had to pull a valve cover and when we did I found chunks of timing gear teeth in the valve cover that had been shot up through the oil return hole. Upon closer inspection the balancer ring was completely loose on the dampner also. Did a leakdown test before teardown and found some cylinders leaking down 40% When I pulled it down I found all the teeth missing off the top gear just like yours, the balancer outer ring fell off the balancer on it's own, the top of the rod bearings looked like yours, and the skirts were collapsed on the pistons of the cylinders that leaked down bad. I believe what happened is it was lean and got hot and detonated and the detonation did the rest.

[77cruiser]

Come to think of it I had damper go bad, I was checking the timing & could see the ring moving back & forth.
Couple more pics. Didn't take any of the piston tops or plugs, didn't look like anything going on there.

[user-23911]

Need pics of the bores and of the rear main journal.

[BLstangin]

If you had a bad balancer I'd be willing to bet that's what caused the timing gear to loose its teeth as it prob puts a real bad vibration in the front of the crank. Maybe that's what caused all my problems also idk but I know the driver said it was loosing fuel pressure then went down on power and started getting hot and I found the fuel pickup sucked tight to the side of the fuel cell so I assumed all the problems started there but that could have made it detonate and shake the balancer apart idk.

[modok]

I agree.

[77cruiser]

Bad damper cause the bearings to look like that? I think partly it's main bore line.
Checked the crank less than .001 checking 1-3-5 laying in the bearings.

[modok]

Right. Damper killed the chain or chain killed the damper. Not sure which, in either case replace both.

If the clearance is good it WILL work, but if you want to see a perfect wear pattern then you will need to have the housing round and the crush right and so forth. Not "old block with slightly loose caps". I've noticed some people think the housings get bigger with time, they don't, generally they get smaller if anything. Iron is pretty stable stuff but there is no constant but change.

[77cruiser]

5 & 1 are snug not tight 2-3-4 are loose drop right in & can wiggle em.

[stealth]

Tore down my 385 sb with about 18K miles. Engine had good oil pressure 20-25 idle 50 at 2000rpm, 15-40 rotella.
Rods all looked about the same they had .002 pastiguage Mains were .003 .0025 .0025 .0025 .002 .003 F---R.

Why is engine apart at 18,000 miles?

Bearings look pounded out and loose to me....

Nitrous?

[77cruiser]

Tore down my 385 sb with about 18K miles. Engine had good oil pressure 20-25 idle 50 at 2000rpm, 15-40 rotella.
Rods all looked about the same they had .002 pastiguage Mains were .003 .0025 .0025 .0025 .002 .003 F---R.

Why is engine apart at 18,000 miles?

Bearings look pounded out and loose to me....

Nitrous?

Pulled to put in a 421.
No juice.

[pamotorman]

if this is a cast crank the journals have been polished in the wrong direction causing the platelets to be pointing in the wrong direction

[Newold1]

Was this cam in this engine a snout type with a retainer plate or an early style without? If no camshaft retainer was a camshaft thrust button used to stop camshaft walking forward? With those teeth breaking off there must have been some pretty good metal in the oil and the piston skirts and cylinder bores must be pretty scratched up with all that iron running around. I don't think oil pressure was great, not bad but not necessarily great. I not a believer in using Rotella diesel oil in such an engine. Its obvious from the bearing wear patterns and examples on those bearing sample pictures that things were not great from the start and not sure if line boring or honing was needed and done or how straight the crankshaft was or how prepared the crankshaft journals were on initial machining. Also if the torquing of rods and mains were not done correctly the wear patterns can obviously point to incorrect crush loads on those bearings.In any event from these pics I would also say things can be redone with some careful rework and assembly and the engine can do better next time.

[77cruiser]

if this is a cast crank the journals have been polished in the wrong direction causing the platelets to be pointing in the wrong direction

It was a cast crank.

[swampbuggy]

Modok----when you said there is no constant but change, there has never been a statement spoken that is TRUER !! Mark H.