Originally Posted by bpu699 (Post 10504993)

OK, just to simplify things... there seem to be lots of small issues with the motor. But most don't seem fatal...

1) Unusual wear on the IMS bearing. Seems to me that if it were tight, after about 10 rotations of the IMS shaft the bearings "makes" its own clearance by rubbing material down. Not optimal, but is what it is.

2) Main bearings have debris in them. Again, not optimal, but that debris likely landed there in the first 5 minutes of running. After that, it is what it is. Those bearings could have gone 50,000 miles like that, no?

The only really odd thing, is the weird wear on the thrust bearing, like the case was aligned way off. Or somehow the coating on the bearings was 5x thicker than normal...

The inner ims bearing looks like it was "pinched" when tightening the case. Same as dozens of pics on this site when people used glyco bearings in their rod ends and found out they were uneven thickness, etc...


Take your current worn thrust bearings, put them on the crank and IMS shaft, reassemble, retorque, and measure the endplay clearance...just to see what it is now.

Like I said before, my removed IMS bearing had lots of wear on the thrust surface...

The "new" IMS bearing fit, but had almost zero play...


Before you start putting in new parts, use the old ones and measure everything again. Until you find what was wrong it will continue to worry you...

If you used glyco bearings, my limited experience showed that they had waaay more clearance than the Porsche bearings. Measure the glyco bearing against the Porsche bearing, its about .0005 thinner, adding an extra .001 clearance when both are installed...

If your rod clearance was too great, that could be your clicking sound you heard...

Originally Posted by dannobee (Post 10504893)

Jamie brings up another question, how did the small end of the rod look? Was the bushing within spec?

The reason that I ask about upside down piston(s) is that the pin is offset to quiet down piston slap noise. It doesn't hurt anything if it's in upside down (it's an old stock eliminator drag racer trick, it'll actually make more power), but it'll have a noticeable rattle.

Originally Posted by jpnovak (Post 10504827)

I have seen some intermediate shafts try to bind on the splines and not spin free. Neil mentioned this about oil pump alignment. Another way is to change how the shaft is clocked to the splines. I would also check the shaft on a V-block and make sure it is straight and not bent. Maybe the tick was the shaft rocking back and forth on the shaft and putting lateral pressure on the thrust bearing. You might see this in abnormal wear at some point on the aluminum layshaft gear.

possible tight links in a chain? Were they new chains? New or old sprockets? Chain lines good? Rubbing the case?

Loose wrist pins? pistons rocking/slapping?

Originally Posted by Trackrash (Post 10505285)

How do the valve guides look? Any loose valves? What about the rockers and their shafts?

FWIW, IMO that ticking sound did not sound like it was coming from deep in the motor.

Originally Posted by lvporschepilot (Post 10506169)

What type of oil filter was being used when the engine was first run? I say this because some filters have a constantly open internal bypass, or can have a very weak internal bypass, meaning unfiltered oil is allowed to just re-enter the engine if a certain pressure is realized. All that fresh engine shrapnel heading straight back into the engine can cause the damages in question sans the oil ring.

Originally Posted by Rich76_911s (Post 10509257)

Hey Jamie,

I'll look again at the layshaft gear. It looked Ok when I first inspected it, (no pitting or cracked teeth).

I did use new chains, and new sprockets.

The chain (particularly 1-2-3 Side) could have been rubbing. The case definetly has some wear on the pathway between the IMS and the Cam sprocket. Only problem is I'm just not sure if this wear was there before or not. None of my old photos of the case have this area photographed too well. I do remember there was some wear on this area, but I genuinely can't remember if it was this bad or not. I totally remember the green arrows, I just can't recall if the orange was there before or not.

http://forums.pelicanparts.com/uploa...1562008956.jpg

Originally Posted by Neil Harvey (Post 10504306)

When assembling your engine always cover it when you are not working on it. Use a big trash bag. If most DIY's are building in their garage, what are the chances of some foreign object landing inside, unseen?

It comes down to good engine building habits. And those habits start before you even take the engine out of the car. Maybe I will post something later on how I would rebuild an engine if I was doing this at my house. God forbid that ever happens.

Originally Posted by Walt Fricke (Post 10510801)

Bingo - flat topped pistons, no valve reliefs, physically you can install them with the arrow pointing either way, but with a pin offset one way is anti-slap, and the other not.

Were all the arrows (or whatever the installation mark is) pointing at the flywheel?

But do I remember this engine ran fine for a fair while, then developed the sound, which (perhaps serendipitously) led you to disassemble it and find the bearing issues?

Those marks on the chain housing don't look good. Shouldn't be any at all, ever. However, if the chain wheel on that side was installed out when it should have been in, again I'd have thought you'd hear it right off the bat. Was the tensioner nice and stiff on that side? You have to squeeze it in a vice to reinstall the pin so you can reinstall it?

I don't suppose you saved a sample of your oil? Which could be analyzed for metal content?