Align Boring the Crankcase, Help educate this amateur... Options

[stephenaki]

OK, I understand the reason WHY you align bore the case, got it. My question with the 914 case is bearing selection after it is done.

Now, rebuilding my MG engine and selecting bearings was easy, measure the journals and choose the size needed. The 914 case however has a set on the journal and a set on the case.

If I have to align bore the case is there a special consideration on bearing selection or do I just measure journals and get a bearing set that accounts for the difference based on balancing of the crank.

May be an obvious question to some but I am confused and want to make sure I rebuild the engine correctly and order the right parts.

[sww914]

There is only 1 set of main bearings, 1 set of rod bearings, and 1 set of cam bearings. When you order main bearings, you order bearings that fit your crank and case. If your case has not been align bored and your crank has not been ground down, you order standard bearings. These will be stamped on the back STD/STD. If your case has been align bored, you order bearings that are oversized on their OD. They will be marked +.25/STD or STD/+.25. I can't remember which comes first, the case measurement of the crank measurement. The +.25 is the new case dimension, the hole is now .25mm larger than stock, which is the same as +0.010".
If the case has been align bored twice or it was really misaligned it will be +.50. The germans mark them in metric and the americans mark them in inches.
If the case and crank have been machined then the bearing stamps will reflect this with 2 numbers, such as +.25/-.25.
It's easy to tell if the case of the crank have been machined previously by measuring the bores in the case and the throws on the crank. If they are standard, they will measure in whole numbers- ie 76mm, 45mm, 82mm, whatever. If they have been machined, they will measure larger for the bores and smaller for the throws in increments of .25mm. If your crank throw is 44.75mm or the bore is 76.25mm then each has been machined.
I don't know if any of the numbers that I listed are relevant, I just made them up as examples. The rod bearings are different. They don't change the OD of the bearing because they can machine down the flats of the rod end and cap to make the hole smaller and then bore it round again, maintaining the standard bore, so if the rod throws on the crank have been machined down, the bearings will be marked -.25 to accommodate the smaller crank dimension.
I'm sorry that I don't have a type 4 case, crank, or rods laying around to give you actual dimensions, but my stuff is running right now.