[JLMounce]

Originally Posted by hurryinhoosier62

The BHJ block fixture is one of the greatest inventions to aid engine machinists. No matter what marque of block you are machining achieving equal block deck heights is as simple as sitting the block in the fixture and adjusting it.

I had to look these up as well. I wasn't familiar with the machine. They also utilize one of the new Rottler honing bays. They were pretty proud of that piece of machinery.

Originally Posted by grivera

Sounds like a solid plan- is 10.35 compression enough for the 242/248 cam?

I think it's on the edge. I don't have a heavy car and I've got enough stall that it may not be an issue. But I'm talking to a number of different people and taking opinions anywhere I can get them. Something in the "old faithful" size, or very slightly larger may be a better suited choice given the estimated compression ratio.

[JLMounce]

Finally got a full weekend that I wasn’t busy, so I was able to get the engine out and disassembled.

I didn’t document much as I just wanted to get things done, but I’m left a little befuddled. No major smoking gun on what caused the engine to start eating its bearings.

Starting with the intake, the gasket had failed at the #6 cylinder which explains why that hole was far richer than the other cylinders. The gasket failed enough that it was covering about 3/4’s of the port. I’m nearly positive it ingested some of the gasket as well.

All of the rod bearings showed severe wear down to the copper. The bearing for #5 appeared to have turned slightly, but the halves hadn’t ridden on top of each other.

The mains looked mostly okay, but a couple had what appeared to be some fretting.

Overall the crank is in decent condition. I think it’ll get by with a polish instead of needing to be cut.

I didn’t measure anything but I had a couple of clearance concerns. It appeared that the crank end play was very tight. If I had to guess, no more than .005 and it didn’t have much of any free clearance. Additionally the rod side clearance on #1 and #2 was pretty much non-existent. #3 and #4 were also fairly tight, certainly less than the crank end play. Remaining rod side clearance was quite a bit wider.

Cam, cam bearings and all lifters don’t even have a witness mark on them. The rollers anre tight, roll freely and Have not pitting on them. The cam lobes likewise have no wear. Everything there looks really good. Only a couple small nicks in the BOP composite distributed gear. I’ll grab a new gear for peace of mind.

I’ll drop the block and related parts at the machine shop tomorrow and send off the heads and intake for work as well. If all goes well I’ll hopefully have the engine back sometime in September.

[grivera]

Very interesting findings- what is the history on the bottom end?

Is the intake being ported?

[JLMounce]

Originally Posted by grivera

Very interesting findings- what is the history on the bottom end?

Is the intake being ported?

I don't know much of the engine's history. When I purchased the car in 1998, the engine was claimed to be fresh at the time. The previous owner didn't furnish any receipts or documents related to the engine build.

I did the cam, lifters, head and intake in 2015. So other than knowing the engine had factory rods, crank and TRW pistons, how it was put together, with what type of bearings etc. was always a mystery.

Yes, the intake is being ported as well to match the heads.

[Formulajones]

Yeah I didn't think you had a roller lifter problem based on your other diagnosis.

The fact you got 16 years out of a short block you don't know the history on I'd say you did pretty good. Now you can build it back better and not have to sink as much money in it as you might have initially thought

[JLMounce]

Originally Posted by Formulajones

Yeah I didn't think you had a roller lifter problem based on your other diagnosis.

The fact you got 16 years out of a short block you don't know the history on I'd say you did pretty good. Now you can build it back better and not have to sink as much money in it as you might have initially thought

I'm still doing the full build, so the money isn't necessarily changing. Although, I'll be able to sell the cam. I know there's a couple people looking for stump puller type cams.

You're correct, this will be the engine for the next 20 years or so.

[NeighborsComplaint]

Originally Posted by JLMounce

I don't know much of the engine's history. When I purchased the car in 1998, the engine was claimed to be fresh at the time. The previous owner didn't furnish any receipts or documents related to the engine build.

I did the cam, lifters, head and intake in 2015. So other than knowing the engine had factory rods, crank and TRW pistons, how it was put together, with what type of bearings etc. was always a mystery.

Yes, the intake is being ported as well to match the heads.

Yep, just as I described. The bearing gets hot, sticks to the crank and turns enough to restrict the oil hole. The bearing shell rides up the connecting rod journal. The locating tabs act like wedges to pinch the bearing against the rod, taking up the oil clearance and the whining noise ensues (like a a worn pinion bearing). You have to run it for quite a while while before it grinds enough clearance for the knocking to start.

Best of luck on your rebuild.

[JLMounce]

Originally Posted by NeighborsComplaint

Yep, just as I described. The bearing gets hot, sticks to the crank and turns enough to restrict the oil hole. The bearing shell rides up the connecting rod journal. The locating tabs act like wedges to pinch the bearing against the rod, taking up the oil clearance and the whining noise ensues (like a a worn pinion bearing). You have to run it for quite a while while before it grinds enough clearance for the knocking to start.

Best of luck on your rebuild.

This is pretty much what the machine shop said as well when I dropped it off this morning. I had them look at the thrust bearing and they noted that it was normal.

Sounds like the engine just got old and tired. If this 10K investment lasts another 20 years, I'll be happy.

[NeighborsComplaint]

You got your money's worth. x2!

Build it bigger and better!

[Dragncar]

Sounds like you started to stack a bearing on a cast rod. Shut her down just in time to save it.
I bought a 455 that had a severely stacked bearing on a cast rod, crank was just 30 seconds from snapping a rod.
Something you need to inform your machinist about. You need to bore it at least .008 under, not .004 under like you do with a Chevy.
The problem is Pontiacs distort .004 or more a 1/2" under the head bolts. You want your bores completely "round" after all.
If he can bore AND hone with a tq plate, great.
I asked for that on my 461 but he could not do it with his equipment. So he bored it .010 under and honed the rest with a tq plate.
Oh, I would run a Molnar rod all day long over a Eagle and they are about the same money.
I had to have a set of Eagles honed on the big end as they were tight when new.
Good luck with your new build. Getting it back by September would be fantastic.
A stacked rod bearing is why I tell all who want to listen, by forged rods. On just about any engine unless dead stock.
These things are too expensive to do otherwise.

[JLMounce]

Originally Posted by Dragncar

Sounds like you started to stack a bearing on a cast rod. Shut her down just in time to save it.
I bought a 455 that had a severely stacked bearing on a cast rod, crank was just 30 seconds from snapping a rod.
Something you need to inform your machinist about. You need to bore it at least .008 under, not .004 under like you do with a Chevy.
The problem is Pontiacs distort .004 or more a 1/2" under the head bolts. You want your bores completely "round" after all.
If he can bore AND hone with a tq plate, great.
I asked for that on my 461 but he could not do it with his equipment. So he bored it .010 under and honed the rest with a tq plate.
Oh, I would run a Molnar rod all day long over a Eagle and they are about the same money.
I had to have a set of Eagles honed on the big end as they were tight when new.
Good luck with your new build. Getting it back by September would be fantastic.
A stacked rod bearing is why I tell all who want to listen, by forged rods. On just about any engine unless dead stock.
These things are too expensive to do otherwise.

The cylinder walls are in great shape. Much of the cross-hatching is still there with some minor thrust side wear. The block will only get honed to spec for a +0.040 piston, and done so with a torque plate. It's also getting a stud upgrade on the mains.

They went straight to the eagle rods, but can get Molnar and included in the quote is honing of the small end for the eagle stuff. It's my understanding they are produced undersized specifically to be honed to the builder spec. If the molnar rods are similarly priced, I'll opt for those.

[johnta1]

Make sure the machinist cleans the lifter oil galleys out good. With all the bearings junk plus the lifters junk, you need it cleaned well.

[JLMounce]

Originally Posted by johnta1

Make sure the machinist cleans the lifter oil galleys out good. With all the bearings junk plus the lifters junk, you need it cleaned well.

Yup, I have already discussed this with them. They'll remove all lifter galley plugs during the cleaning process.

[Formulajones]

Originally Posted by JLMounce

The cylinder walls are in great shape. Much of the cross-hatching is still there with some minor thrust side wear. The block will only get honed to spec for a +0.040 piston, and done so with a torque plate. It's also getting a stud upgrade on the mains.

They went straight to the eagle rods, but can get Molnar and included in the quote is honing of the small end for the eagle stuff. It's my understanding they are produced undersized specifically to be honed to the builder spec. If the molnar rods are similarly priced, I'll opt for those.

Just had a set of Molnar rods done and the small end had to be honed on those too. No big deal

[JLMounce]

Originally Posted by Formulajones

Just had a set of Molnar rods done and the small end had to be honed on those too. No big deal

Good to know, thanks.

[Shiny]

Originally Posted by NeighborsComplaint

Yep, just as I described. The bearing gets hot, sticks to the crank and turns enough to restrict the oil hole. The bearing shell rides up the connecting rod journal. The locating tabs act like wedges to pinch the bearing against the rod, taking up the oil clearance and the whining noise ensues (like a a worn pinion bearing). You have to run it for quite a while while before it grinds enough clearance for the knocking to start.

Best of luck on your rebuild.

Originally Posted by Dragncar

Sounds like you started to stack a bearing on a cast rod. Shut her down just in time to save it.
I bought a 455 that had a severely stacked bearing on a cast rod, crank was just 30 seconds from snapping a rod.
Something you need to inform your machinist about. You need to bore it at least .008 under, not .004 under like you do with a Chevy.
The problem is Pontiacs distort .004 or more a 1/2" under the head bolts. You want your bores completely "round" after all.
If he can bore AND hone with a tq plate, great.
I asked for that on my 461 but he could not do it with his equipment. So he bored it .010 under and honed the rest with a tq plate.
Oh, I would run a Molnar rod all day long over a Eagle and they are about the same money.
I had to have a set of Eagles honed on the big end as they were tight when new.
Good luck with your new build. Getting it back by September would be fantastic.
A stacked rod bearing is why I tell all who want to listen, by forged rods. On just about any engine unless dead stock.
These things are too expensive to do otherwise.

This engine failure has to be very upsetting.

Help me understand the cause better. I don't understand how a rod bearing that's been happy for 15 years decides to check out. How does this happen?

Heat is mentioned, but why?

When one of these bearings is set up with the right clearance, oil pressure is good, and there isn't any detonation, what causes the bearing to suddenly decide it needs to spin?

Does the wear that occurs during start and stop cause the "initial" friction to increase over time or ????

Or is the cast rod to blame? Does it somehow get deformed over time? If so, why?

I know it doesn't matter. The failure happened, the bearing bound up somehow, but I'm curious about what leads up to this.

Mike

[Jay S]

If the bearings were just look at around a year ago while repairing an issue with the dipstick, and they looked good. Given the time frame and miles this all happened, it really should not have happened. If it hadn’t been for that inspection, I would agree it was just time, and for sure it has enough miles on it now it doesn’t owe really you anything. After an inspection, for the short amount of time and miles since then, it sure would be nice to find a smoking gun. Maybe it traces back to the fuel pump going out on the EFI, or something not quite put back together correctly after the inspection. Those are the best things it could be. The worst are something that gets overlooked and put back to kill the next overhaul.

[Formulas]

Are those stock rods sporting ARP bolts? .... Maybe they were not resized ....... No rod big end side play or very little? a few rod caps misplaced? fits with ruined bearings as well

[JLMounce]

Originally Posted by Jay S

If the bearings were just look at around a year ago while repairing an issue with the dipstick, and they looked good. Given the time frame and miles this all happened, it really should not have happened. If it hadn’t been for that inspection, I would agree it was just time, and for sure it has enough miles on it now it doesn’t owe really you anything. After an inspection, for the short amount of time and miles since then, it sure would be nice to find a smoking gun. Maybe it traces back to the fuel pump going out on the EFI, or something not quite put back together correctly after the inspection. Those are the best things it could be. The worst are something that gets overlooked and put back to kill the next overhaul.

I never pulled a rod bearing, just the main cap needed to pound in the new dipstick. So I never really could determine health of the rod bearings.

It's certainly possible that the issues I was having earlier in the year may have contributed.

Originally Posted by Formulas

Are those stock rods sporting ARP bolts? .... Maybe they were not resized ....... No rod big end side play or very little? a few rod caps misplaced? fits with ruined bearings as well

The hardware appeared to be stock hardware. #1 and #2 had extremely minimal side clearance. To the point that you could get anything in between the rod big ends. Not without the use of a hammer to drive something between them.

[hurryinhoosier62]

Originally Posted by JLMounce

Finally got a full weekend that I wasn’t busy, so I was able to get the engine out and disassembled.

I didn’t document much as I just wanted to get things done, but I’m left a little befuddled. No major smoking gun on what caused the engine to start eating its bearings.

Starting with the intake, the gasket had failed at the #6 cylinder which explains why that hole was far richer than the other cylinders. The gasket failed enough that it was covering about 3/4’s of the port. I’m nearly positive it ingested some of the gasket as well.

All of the rod bearings showed severe wear down to the copper. The bearing for #5 appeared to have turned slightly, but the halves hadn’t ridden on top of each other.

The mains looked mostly okay, but a couple had what appeared to be some fretting.

Overall the crank is in decent condition. I think it’ll get by with a polish instead of needing to be cut.

I didn’t measure anything but I had a couple of clearance concerns. It appeared that the crank end play was very tight. If I had to guess, no more than .005 and it didn’t have much of any free clearance. Additionally the rod side clearance on #1 and #2 was pretty much non-existent. #3 and #4 were also fairly tight, certainly less than the crank end play. Remaining rod side clearance was quite a bit wider.

Cam, cam bearings and all lifters don’t even have a witness mark on them. The rollers anre tight, roll freely and Have not pitting on them. The cam lobes likewise have no wear. Everything there looks really good. Only a couple small nicks in the BOP composite distributed gear. I’ll grab a new gear for peace of mind.

I’ll drop the block and related parts at the machine shop tomorrow and send off the heads and intake for work as well. If all goes well I’ll hopefully have the engine back sometime in September.

An engine that is too tight is just as bad as an engine that is too loose. With little to no end play on the crank and two sets of rods with little to no side clearance is more than enough to trash a set of bearings. I’ve heard good things about DSS pistons; what makes them good for me is their plant is four hours from my house! When you take your crank in have them magnaflux it, paying particular attention to the crank and rod journal fillets. Sometimes when a crank is slamming around in the main saddle with little to no end play cracking can start in the fillets. If they find cracking has begun in the fillets it’s no problem to perform a good radius job on the fillets when grinding a crank undersize.