Well, we pulled the motor and performed the autopsy this weekend. The conclusion was the #1 main bearing spun and realigned the oiling port onto the shuffle pin (based on the marks on the bearing). This was either a condition inherited from the previous builder , or somehow the crank came out of the bearing slightly when the case was split to fish out the steel washer . Either way, it obviously caused bad things to happen. Fortunately, all of the big expensive parts seem to have emerged for the most part unscathed. The crank, pistons, and heads all look great. The bearings all have signs of damage, and if I had run the motor any longer it probably would have scattered.

Looking at it, the #1 cam bearing pretty obviously starved, and eroded (no tin at all left on the bearing surface). That is the most glaring damage visible. Other bearing surfaces have signs of scoring, some more than others. The cam and lifters are being replaced as a matter of course, and all the bearings too. There appears to be bearing surface material deposited on other bearings in the motor. I think I got off REALLY LUCKY considering what -could- have happened.

Now the question...

While trying to figure out how the heck this happened, I observed that the shuffle pins were all pretty loosely fitted into the case. I could easily wobble them with my fingers, and could lift them out with just finger pressure holding them. Is this right? Should they be tighter? If they need to be tight, is the case toast at this point? Can I retrofit pins that fit tighter? Should I <cringe and shudder> epoxy them into place? Or should I just pull out a spare case and start over?? If they are supposed to be loose, please tell me that too... I'd like to start measuring everything out for a rebuild as soon as I can...

Thanks!

-Josh2

the pins that hold the crank bearings in line are just laid place...no need for any epoxy.
This type of error happens frequently so dont feel bad..it probably happened when you cracked the case.
Now you can remember how critical the little pins are...they keep the bearing and oil galleys (thus oil pressure) all lined up.

You probably starved the cam due to the blocked oil galley on the crank..

Get the crank checked and polished...it needs it.

when you put it back together...each step turn the crank by hand..no wrench.
Between that feel and the spacing of the case you should know if its all lined up.
the pin can jam into the case or jam into the bearing when you crank down the bolts...
Done right, the case needs no help at all to close up perfect. If you need to hit it or use a bolt to close it...something is wrong and typically its one of the pins.
Rich

Nice to know. Thanks!

Just an additional question...

It doesn't appear to me that this could have been the cause of the very load banging noises that made me shut it down. I could be very wrong, and it certainly wouldn't be the first time, but could this bearing displacement and wear cause those noises?

Thanks!

-Josh2

Yes, very much.

First, the crank wont spin freely.
Second...lack of oil pressure going to all the main bearings and rod bearings...loud banging results.

Crank wobble also due to bearing spinning.
Crank bearing spinning and hitting the pin each time...loud banging.

Dont feel bad about this...its amazing how many have done this exact mistake.
You live and learn with these motors.

Fun note..the pin costs less than a dollar...its always the cheap parts that kill you.

just remember..the case will go together with NO force at all..if you see it stuck..pull it apart and start over...something is misplaced.

Rich

I thought I answered this. I agree, the pin was dislodged when you pulled it apart, and all your problems as described probably result from that brain fart. A semi-loose fit is OK. BTW, the pins you're talking about are called "main bearing dowel pins". "Shuffle pins" are tubular inserts in the main bearing webs concentric on the case through bolts (or sometimes hardened pins set somewhere near the throughbolts), and are designed to keep the main bearings aligned under stress, as well as keeping the faces of the webs from eroding. 911s have some, and people often add more. I've put 'em in high revving T4 motors (along with piston squirters). Some people don't like 'em. The Cap'n