Hello.

My 1911cc rebuild is progressing.

The machine shop called today to tell me that my 1.7 case is in really good condition, but it does need the crankshaft bores to be align bored. The crankcase supports have .004" out-of-round measurement at 45 degrees, but otherwise correct. The crankshaft journals themselves are in very good shape and only need to be polished. It still within standard spec.

Which bearings should I go with? I see bearings here and there but I'm not sure exactly what I need. Brand, size, material, etc.

Thanks,
Marcus

If the shop that wants to align bore your case, and has your crank on hand, doesn't have the bearings...........Don't let them cut that case........... they should have the bearings on hand to complete the job properly.

No, no. That's not the case.

My machinist is super, but he doesn't have VW jigs. But he is a 914 guy. We have to send the case to a specialty outfit to do the align bore. The reason I'm asking about bearings is because it's my job to find correct ones. I understand that the OD of the bearing needs to be slightly larger to suit the soon-to-be slightly larger bores. I just need to know who has the best bearings and which size to get.

-m.

With the quality of the bearings that are available today it will be a crap shoot. The case will need to be cut to give the bearings proper crush as to allow the proper oil clearance between the bearings and the crankshaft journals. You should get in touch with a fellow on here: Jesco Reient (John) Look at this post for further information on this: 914 World

Go see if the type 4 store sells oversized bearings.

Either he has some, or AA has some.
They bought a large amount during the last run.

Rich

EMW may also have them, and they can do the correct machining with the bearings in hand...



Rich

If you can even find bearings... Find some first and line bore to fit. High performance house had some good German units for sale recently.

Yes, thanks for the hints. I've sent off a few dealer inquiries.

My issue seems to be that I need 0.25mm extra for the case, but the crankshaft itself is still standard size. Everything I'm finding is exactly backwards of that. Or I'm backwards. That wouldn't surprise me.

-m.

Usually, the "hungry" machine shops, ie. (cut that case if it needs it or not) will only cut the case 0.020 " or .050 mm which will bring it to within the range of first cut case dimensions for the available first oversize case bearings. (Crap Shoot)

A real machine shop will cut the case to a dimension that will yield the proper bearing crush to give the correct oil clearance between the bearings and the crank. It will take a little more time to determine the case cut necessary to yield the proper crush..........Then the crank can be polished to obtain that "perfect" oil clearance.

This type of machine work will cost you more because it requires more time to "fit" the bearings to the case and crank, but will yield a more perfect fitment and assure longer engine life through better oil pressure obtained by proper case, bearing and crankshaft fitment.

Most places available run a cutter through the main saddles to obtain the first case oversize 0f .020"/.050mm, they have a set of bearings that are reputed to fit the first oversized case dimension. They may or may not require the presents of your crankshaft for measurement, but simply assume that the measured and polished standard or cut crankshaft will somehow fit the bearings with proper oil clearance.

If bearings were available that were perfect enough to insure proper crush and oil clearance on a cut case with a standard, or a first cut or second cut crankshaft all would be well and good...........but with all the variables it is a gamble.

Oversized case bearings are only available in increments starting at .020"/.050mm, the next size would be .040"/1mm.........no such animal as .010"/.025mm

There's only one case cut for the T4 engine, .020" (.5mm)

Always have the bearings in hand when setting up for the align bore. I see bearings vary by .002" or so all the time, which is more than the bearing crush tolerance.

Thank you gentlemen. I have it all figured out. Thank you all for the insight and corrections.

-marcus

Here's an update.

Mike Bellis is the winner!

I contacted Rich at High Performance House (http://www.highperformancehouse.com) on Mike's suggestion. Rich spent several days working with me back and forth over email to make sure I had exactly the right plans, measurements, etc. Very cool guy to work with and put up with my many questions. And guess what precious Kolbenschmidt gems arrived via FedEx today?

THESE:

Click to view attachment

Victory!

Rich is great and a real asset to the Porsche community.