Stan.Shaw@Excell.Net

Actually your first statement on this motor issue was based on a photograph where you stated the rod cap was on incorrectly. It was pointed out the the numbers were properly aligned and that the cap could not be installed incorrectly as you suggested. It was also stated that the alignment of the outside surface of the rod cap was not of concern, it was the internal machining that was important.

You also threw out a theory about how it could have been mis-installed at the factory, as had happened at a Chrysler plant. You also suggested that perhaps it two different rod caps that happened to have the same 1 of 1000 serial numbers might have gotten mixed up.

Only when the audience continued to question your theory did you go off and measure.

What is clear to me, is that you decided from the initial photo what the problem was, and then tried to create scenarios that supported that theory.

I note in the photo you are using as evidence in this post, the 2/6 rods are not even viewable, which is what Dave said the failure occurred on. So, now your evidence is only that since that one rod bearing cap's external surfaces are misaligned, it must be true of the 2/6 rod bearing cap as well. Although the failure did not occur in the bearing cap you found the external surfaces were misaligned on. (edit: note I realized afterwards I was upside down when looking at this, the 2/6 rod bearing cap is visible.)

My statements here aren't for you to refute, but for others to read and consider for themselves.

brutus

The rods are not centered on the rod bearing unlike the 944. 928 rods have a larger lip on the side away from the adjacent rod. You might as well be suggesting that the cap was upside down as backwards. Is anyone running a scrapper set up successfully ?

Lizard928

Kevin, everyone who works on the 928 knows that the passenger side bank (LHD cars) is 1-4 and the drivers bank is 5-8, which yes puts the #2 and #6 on the same crank journal.

It really doesnt matter what the outside of the conn rod looks like either. it could have an extra 1" on one side and it wouldnt matter, the ONLY thing that matters is that the holes are the correct size and distnace appart, and that the conn rod was line bored with the hat bolted to it. And stamped, the outside doesnt matter at all. I have a hole pile of rods sitting at home, and trust me they ALL have abit more material on the outside of the lower half.

just like Stan I am not saying this to get into a pissing contest, simply stating this so that other viewers can see both sides of the tables and draw there own conclusions.

Stan.Shaw@Excell.Net

Well, I don't sell any such parts, so what else would be my point here? I would like to see more 928s on the race track, and it won't happen if they receive incorrect information.

Since you are a professional, it seems you should check your facts before posting then, since you are clearly wrong in much here. I am not a professional in this, so usually check my facts before posting such a response

You are the professional posting responses before checking your facts, not me. I don't expect you to know anything offhand, but I certainly think you should review your facts before posting.

Now we are into "create a fact". I never said Porsche was unique. Perhaps you are referring to my comment that your comparison to Chrysler manufacturing was unreasonable, but it is quite a stretch to state that I think Porsche is unique. Here, I have to say "get a grip".

No clue what you are referring to, nor do I care. Your science seems to state what you "think", then check your facts, but work to make those facts back up what you "think".

Correct, I was thinking the engine stand was on the front of the motor, but of course it is not.

Stan.Shaw@Excell.Net

The thread title is "Drilled Crank Thoughts" not engine scrapers...

brutus

The rod and the cap are cast forged in two seperate operations they have no relationship to each other until they are bolted together and the final machining takes place for the bearing surfaces at which time they both get stamped. And as was mentioned you can not reverse a cap and still fit a bearing inside it. The arguement about variations in a Mitsubishi engine only reinforces the FACT that the easily visible surfaces misalignment of the irregular outer sides of the rod and cap has nothing to do with anything especially the fact that the engine failed.

atb

Isn't there a chamfer on only one side of the big end to mate to the rod journal fillet that would prevent a rod cap rotated 180 degrees even before being sized from fitting properly? Or is that what you guys are already saying?

brutus

Right the bearing surface is offset from the centerline of the rod such that you can not flip a cap around and still fit it to the bearing. Which makes this latest discussion nonsense at best.

Lizard928

actually you can put the cap on backwards, and can even start tightening the threads, but as soon as you put any tension on those threads the bearing halves may visiably move and the crank will not be able to be turned. It WILL lock the crank in place and prevent it from being turnable. and if you continue to tighten further you would damage the crank rod and bearing.

I still think there is no way that cap was on wrong, ESP if the car ran for awhile before failing.

Bill Ball

Engine assembly jobs that I have been involved in included very precise checking of the big end bore of each rod/cap pair for diameter at multiple points. Wouldn't that have picked up this possible issue? I would assume this was done, especially in a rebuild of an engine with bearing failure. In any event, it could be checked now.

Andre Hedrick

Can this be done for a 4.5L also?

drnick

andre, i dont think it matters if its a 4.5 or 5.0 - you cant put the big end caps on backwards..

Vilhuer

All 928 rods have exact same critical dimensions including 2mm nonsymmetry at big end.

Stan.Shaw@Excell.Net

Umm, nobody said anything about not reading the thread, but if you remember the whole quote I used (which you chose to drop), my comment was in response to your above comment. My point is you say people accuse you of being a salesman when you defend your product too earnestly.... Well, here we have a thread about drilled cranks, and your product was merely mentioned as being on an engine that failed and you immediately. Dave didn't say your product caused the failure, did he?

So here you are jumping to conclusions about the cap being on backward, which has been suggested by a number of people as far fetched. Since that theory is lacking (with the numbers aligned), you are now leaning heavily on a theory that the cap is from a different set, that happened to have the same number.

This "earnest defense" is based on the external surfaces of a rod bearing cap not lining up, which has been pointed out a number of times as irrelevant as the inside machining is what matters.

So, yes, you do come across as a salesman, and unfortunately for you, a salesman that had a theory based on a photo and works hard to contrive evidence to match the theory.

Maybe the only problem 928s have with the 2/6 rod bearings is that they all have mismatched rod bearings caps that coincidently have the same number of the rod.

Daniel Dudley

I haven't built an engine in years, but it only takes one chip of steel, or one piece of crud to create a disaster like the one Stan has.

Stan, I see that the cost of the crank is an issue for you, but the question isn't whether you can afford to replace the crank , the issue is whether you can afford NOT to replace the crank. And you need to have all the rods reconditioned or at least checked out again, and then you need to clean, clean, clean. You should go over the block for straightness as well, all the usual stuff.

If you cross drill your new crank, I would consider sending it to someone else. Don't ask me why, I don't know. And even if I trust the machinist, I still plastigage the bearings.

Bottom line is that you just need to get back up on the horse. And consider picking up a solid short block that you can refresh and use as a spare. There is some peace of mind to having a whole new matched assembly with no question marks around it. Drop the sucker in,and go racing while you build your magic engine. You could probably pick up a beater cheap, and part out what you don't want to recoup your outlay.

Also consider that MK may be right about the friggin Amsoil thing.