I'm bummed

[Bobboloo]

I got my case back from the machine shop and it looks like a botched job.

I had my 7R case redone. Shaved case halves re-bored to standard, oil by-pass mod , case savers, decking, etc.


Problem is the alignment bore. It looks like they bent a few studs and when they mated the case halves they didn't get the left and right side aligned at the front of the case (nose bearing end) before they ran the bore through. The left side of the case was higher than the right and when they ran the bore through it didn't clean out on the top of the left side or the bottom of the right side.

The #1 bearing at the back of the case (flywheel end) specs out fine and is round .051mm. This is probably because that end of the case has the hollow alignment pegs that surround the studs. The other end of the case has no alignment pegs and is basically aligned by the #8 nose bearing. When they bore there is no nose bearing in place and therefore nothing to align the case and if the shop doesn't make sure it's aligned I guess this is what can happen.

I decided to go ahead and torque the case together with the bearings and crank to check clearance with plastigauge and sure enough the front end of the case (#8 side) is out of spec. It's got over .076mm clearance at the top and bottom of #6 and #7 bearings with .038mm clearance in the middle of the bearings. In short the bore is oval on that end.

.010mm to .072mm is considered the clearance limits according to Waynes book. I'm beyond that with over .076mm of clearance. .076mm is the end of the scale on the plastigage green paper. My guess is I'm around .85mm

Now that the case halves are shaved I can't go there again without screwing the deck height.

What would you do? Have them bore the case for oversize bearings or ditch it and start over.

I'm at a loss on what to do next. This case was my foundation for my 2.8 RS MFI twin plug motor. It's not a cheap motor I'm building. I've got rebuilt twin plug MFI heads with all new valves, Nickies, JE's, rebuilt MFI induction. I just can't see putting the motor together on this case in it's present condition.

case leftside:

case rightside:


The dark areas are where the bore didn't cleanout and the additional clearance has shown up. You can see it on the intermediate shaft bores as well. They buggered the leading edge as well on those bores. It looks like the bore did a little dance before it settled in.

[racing97]

It appears someone did a "standard hone" (this hardly every works) with out the #8 brg.
Now you will need to bring it to a shop where they can punch all 8 brgs .010 or .25mm over. Normally no one touches the #8 and buying a bearing set will be considerably more expensive. I believe the dealer is the only one that carries that complete "first over"on the case side bearing set.

best regards

[BURN-BROS]

Bobby, can they make good on another case? I find it odd that they didn't QA their work. Contact the company that did the work and see what their position is. Sorry that it happened to you.

[camgrinder]

Give Ted Robinson a call at German Precision. He can give you some good advice. He can also bore the case to the next oversize and probably furnish the oversize bearings.

German Precision INC

[Bobboloo]

Aaron, I just measured last night so I'll call today. I have my thoughts on what happened as stated above but I don't know if I have a leg to stand on because these cases twist and as such the shop can have it's thoughts on what caused this as well.

All I know is when I got the case I immediately noticed this mis-alignment from looking at the #8 end with the cases mated. (Left side high) I opened the case and found bent studs in the direction that would cause the error. When I straightened them and torqued the case with the #8, crank and the rest of the bearings the case halves lined up but the bore was off according to the plastigauge.

John, I'll give Ted Robinson a call. I'll call when I get back from London. I'm leaving at noon today.

Thanks guys

[911pcars]

I wouldn't incur more expense on behalf of your machine shop. They made a mistake and they should provide restitution. Request their agreement, then find or have them locate another 7R (or al) case to rebuild; maybe another vendor as well. Going to oversize bearings means your cost for bearings (and subsequent replacement bearings) will be quite higher.

Sherwood

[Eagledriver]

I'd try to get them to do an overbore (correctly this time) and pay the difference in cost on the bearings. Ted can get you the bearings at his price from the dealer but they are still around 500 dollars and that is without the #8. If you are going to get the bearings from Ted at his cost you should throw some work his direction.

-Andy

[asphaltgambler]

No, I would stop here with these guys. I find that if the shop didn't / couldn't do the job properly the first time; go elsewhere. You are just asking for additional problems.

Find a reputable shop to repair their 'fix' or you could be building a very expensive boat anchor.

[BReyes]

Serious bummer. Slow down and possible more expense. I'm sure you will have it rectified.

Good job to take your measurements. Hang in there, you will have it resolved.

Have a safe trip.

Regards,

[asphaltgambler]

Yes it shows attention to detail on your part. These cases are the foundation of this build. Be cautious.

[ischmitz]

Ooops, that is a disapointment. I would not do more business with that machine shop unless there is

a) a reasonable explanation why this happened (the machinist was on vacation, the owners' son's GF did an internship, they had a monster garage party, etc)

b) the shop is willing to make good by getting you the 1st OS bearings and rebore the case or getting you into another 7R case.

I worked with Walt@CE. His work is truely outstanding and you know he does it right. Great peace of mind.

Good luck,
Ingo

[porschejeff]

I have two 7R cases available, if you need a backup plan

[Bobboloo]

Hi guys,

I just got back from London. Sorry for the delay.

To update you. The shop that sublet this work has been standup and wants to rectify the problem. I have no complaints with them what so ever.

Let me re-state that I have my thoughts on what happened but I'm by no means an expert.

I just need to decide how I want to proceed. I recieved some emails offering help from people that I would consider experts. I'll let you know what direction I take.

[afterburn 549]

That s my thought,anyone is allowed a mistake,a bad busness waffles,and the good ones shine at that pt.

[Bobboloo]

Well I finally have an update to report to you guys.

I've been in a bit of a quandary as to what to do. I had the option, available to me, to take the case back to have it redone no charge but I wasn't sure that I wanted to do that. I guess I just lost confidence in that shops ability.

I've been at GAF the last two days and was talking to Walt at Competition Engineering about my case. Saturday he told me to bring it by and he would take a look at it. So today, Sunday, I brought the case along with me.

He came to the same conclusion as I had, about the case, when he took a look at it but he also said it wasn't so bad that he couldn't fix it by shaving the case halves again to return the case to standard.

Basically, when he does a case he usually takes a rubber mallet and slowly taps the nose end of the case halves and "makes sure" that the halves are aligned correctly before he fully torques the halves together.

I saw a case he had just done for Tom Woodford and his attention to detail was evident. There's a reason why his work is "relatively" pricey. I say relatively because obviously It would have been cheaper for me if I had just gone to him to begin with.

As for any issues of re-adjusting the deck height back to normal with cylinder base shims. Walt felt that If I shim the chain housings accordingly that I should have no problem with binding.

I'll let you guys know when I get the case back. It looks like the 2.8 twin plugger is back on.

[dtw]

Heard a lot about CE's work, look forward to seeing some pics!

Glad that you are 'back on the path' after your initial disappointment and setback.

How do you shim the chain housings?

[Bobboloo]

How do you shim the chain housings?

Good question. I guess I could just buy extra gaskets and stack them or maybe I could buy a copper sheet the same mil thickness as the cylinder base shims and make my own.

[911pcars]

The cam-to-crank distance changes when material is machined from various engine components (cylinder head, cylinders, crankcase spigot surface, crankcase mating surface). Except for factory stock engine parts, rebuilds will be unique in this regard.

In order for the cam to remain centered in the chain box opening. the chain box mounting surface must be machined or spaced out accordingly. I would suggest a dry fit of the "cyl. head/cylinder stack" along with used gaskets and determine where the the chain box has to sit, then go from there.

Sherwood

[Bobboloo]

Diffenently a dry fit is in order. I have a lot of variables to deal with here. Shaved halves, decked bases, re-surfaced heads, JE pistons and twin plugs. I'm also going for a minimum deck height to help prevent detonation. It may take a few re-assemblies of the base components to get it just right.

[Wayne 962]

You only really need to shim if you're *way* off, and the chains are too slack.

As for Walt - he is indeed very good. I saw that case - looked just like mine, used in the Engine Rebuild Book. It's about $500 to have that procedure done by Walt, and usually about a 4 month wait.

-Wayne