Cracked case, now what?

[Slow 1200]

it's an AR (early 70s euro dual port 1300) case that was purchased already opened for old school NPR 90mm cylinders, when hand fitting 90,5s cylinders (the diameter difference is minimal) we ran into this crack around the stud hole, is the case junk or could this be welded maybe?

[jrandy]

Well.....
It depends on how good your people are and what you are willing to spend and risk.

You could weld the crack, install a case saver and then do a clean-up cut in the cylinder bore(s).

I have run cases with the insert threads showing in the bore with no problems, but it is not the greatest thing.
If you have the parts to put it back together and want to patch it up it can be patched.

Will it last forever? Probably not.

[Stray Catalyst]

The cost of welding this casting, versus the cost of replacing it, does not justify when you consider that it's likely to break again in the same place. Unless that case itself is rare and difficult to replace, get an AS41 case and you shouldn't have the same problem again. YMMV, you may know (or be) an excellent welder who has no problem welding castings that are exposed to constant thermal stress.

Stray

[Marc]

AR cases are essentially similar to AE (so they are AS41 alloy).
How much other work does the case need? If it's not going to need much invested, and you're only going to build a mild 1775 on it, a Time-sert installed in the (unwelded) hole should hold up for the life of the build. Yes it's sleazy, but it'll run.

[sideshow]

I would use that case with an insert, assuming a hard look found nothing else worn.

[Slow 1200]

the case came from an old shop that closed, apparently someone was building an engine but never finished, it's linebored 1mm over and came with a crankshaft inside and new bearings, everything seemed to check out fine until the crack was found!
The 1776 is/was going to be quite mild, single port cleaned up heads, cb2232 camshaft, single zenith ndix carb, stock everything else, it's going into a 67 camper bus (with no reduction gears) that goes on long trips and sometimes will be pulling a trailer so it better be a sturdy engine!

[perrib]

Like J Randy said there are a lot of engines out there with the threads on the case saver showing.