[dmac]

Is there a way to check for this problem on an assembled short block? I had a shop clean, bore, hone, and assemble a 455 block with a rotating assembly kit from Butler. I am pretty sure it had the FM bearings, but had a cast stroker crank, not forged. Spins pretty easily by hand, but that probably means nothing. Because I supplied all the parts, I doubt if they were checking at the blueprinting level.

[wbnapier]

dmac - Ditto what Tom S said. Chamfer the bearings as a precaution.

Also, I'd have the rotating assembly balanced locally.

[wbnapier]

dmac - You can at least spin it, remove the caps and check one side of the bearing for witness marks on the edge. I'd have a helper pry the crank forward and back a bit as it spins.

What I don't know, is whether we should be concerned about all the main bearings, or just #5. From my machinist, only the new style Clevite #5 is located poorly. According to Butler, it is all bearings.

[tom s]

We are going to chamfer all rear main bearing no matter what from now on!Tom

[mchell]

“The camshaft woodruff key didn't sit well in the groove and I broke one cam gear on install, and another on disassembly. The machinist uses a non-Pontiac one that has a flat bottom and nests better, solving this issue”

Say what?.........please post a pic of the cam that was removed....especially the cam snout and key way. This seems highly unusual?

If the cam was indeed broken on install, you have the catalyst for the rest of the damage?

[wbnapier]

No, you misunderstood me.

On my initial assembly, I chipped the cam gear where it indexes with the woodruff key. I, of course, didn't proceed to use that timing set. I had a backup timing set, which I installed, no problems. When the engine grenaded, I had to disassemble the engine, and when I pried off the timing set, I chipped the cam gear in the same place. These were both cast cam gears.

My analysis led me to believe there was an issue with my camshaft, with the groove in which the camshaft woodruff key nests. I relayed this to the machinist. He replied that he has for years used a flat bottom woodruff key for this reason. They nest cleanly and flat in the camshaft.

I was relaying that bit of info. It is a small detail I would not have known as a 1st timer, but would have saved me some grief and money. It had nothing to do with my engine failure.

[mchell]

Originally Posted by wbnapier

No, you misunderstood me.

On my initial assembly, I chipped the cam gear where it indexes with the woodruff key. I, of course, didn't proceed to use that timing set. I had a backup timing set, which I installed, no problems. When the engine grenaded, I had to disassemble the engine, and when I pried off the timing set, I chipped the cam gear in the same place. These were both cast cam gears.

My analysis led me to believe there was an issue with my camshaft, with the groove in which the camshaft woodruff key nests. I relayed this to the machinist. He replied that he has for years used a flat bottom woodruff key for this reason. They nest cleanly and flat in the camshaft.

I was relaying that bit of info. It is a small detail I would not have known as a 1st timer, but would have saved me some grief and money. It had nothing to do with my engine failure.

Ahhh....So you chipped the timing chain gear that slips on to the cam, Not the cam gear?

Have you found cause and effect yet?....thought you spoke with a bearing rep or two? Any info?

I run Clevite bearings on my build, so I’m curious.