Case junk or not

[Porschefreak28]

i already post this thread in the newbie section and then stumbled onto this section. very new the forum but this is the section thats best for the post. I believe the case was bored because the case # Begins with D0 and ive reaserched it to be a 1200 but the pistons are stamped 91.93. just curious if the case is still good to use because the thread inserts for one of the studs has gone through heres a pic

[Piledriver]

That's not unusual, do not sweat the case savers unless loose.
I didn't know they made 92s for 1200 cases, something doesn't jibe.
Ah, those are the Mexican 1200s -1977... Have never seen one, may be more similar to a late model 1600 case than the ancient 1200 cases.
Hopefully a T1 expert familiar with those will pass by.

Does it have something like AS41 cast into the side of the case?

...but PLEASE don't copy the PO and use silicone sealant like caulk.
It doesn't stick to oil, not even a little.

Ultra Gray or Ultra Copper RTV in a thin smear work well on the bottom seal of jugs---
... if everything is spotless, and you work quickly, get everything torqued pre-cure and do not disturb the jugs once cured.
RTV is a PITA to remove, there are several better alternatives.

[Chip Birks]

40 horses were "big block" 1200s.

[Porschefreak28]

We'll the case saver is loose but luckily I'm rebuilding it for my class and one of the guys that works the tool room there is a air cooled guy. Thanks for the info guys

[Marc]

D0 1200 cases were essentially the same as AE (or whatever) 1600 cases of the same vintage, other than still having 6mm oil-cooler mounting hardware. The bore centers and head stud spacing are the same. "D0" merely signifies 1200cc, the alphanumeric designation debuted in 1965 by which time insert cam bearings were standard (the "9-million" block numbers). As time passed, many 1200 cases even had the same 93.8mm cylinder spigot diameter as 13/15/1600s (instead of 90mm), and used a funny 77mm jug with a big lower spigot - it looked like a 1300 but was ¼" shorter - few of these made it across the pond, but they were the norm on late 1200s in Europe. Some have less-substantial center main-bearing webbing, but I used one years ago to build a 2087cc Class 1 Unlimited off-road motor that kicked ass and had no failures over several seasons of hard usage, so as long as you aren't hitting sky-high revs which'll whip the crank and unduly stress the center main any dual-relief D0 should be fine, virtually the same as a 1600 case. Arguably, the case with the larger backside openings in the center main webs might even be preferable with a counterweighted crank since it'll allow crankcase gases to circulate more freely from one end of the motor to the other.
I am of course assuming that we're talking about a late-model, dual-relief case here and not some small-passage relic from c1965.
The reason that the 92mm bore was generally considered to be the maximum practical many years ago was because of just what you're seeing - with a 96mm nominal cylinder O.D., the m12 O.D. case-savers are just being kissed when the case is hogged out....there's little margin for error, so if the boring's not done just right the inserts can be nicked. Current fashion allows for a 94mm piston in a cylinder that has a 97.25mm spigot - there's room for that in a case with 8mm head studs and 10mm O.D. steel inserts.
The "classic" 92s that you have are infamous for short life and excessive blowby since the cylinders are too thin to retain their shape under heat-cycling, so the rings are constantly trying to break in to a moving target. Years ago the market started offering 90.5mm bore cylinders with the same outside dimensions which yielded slightly less displacement but nearly the same performance (at least when compared after 10-20K mi use). There's no denying that a fresh 1835 will make more power than a 1775, but the latter will be better to live with a couple of years down the road...and burn less oil getting there.
Today the cycle repeats, you can now buy 92mm piston/cylinder sets which use the larger O.D. of the 94s - these offer ample cylinder wall thickness and finally give us the option of 1835cc with good longevity.
For a case with 10mm studs/12mm O.D. inserts, you can take these modern "thickwall" 92 cylinders and have them turned down to ~96mm so they'll plug in without removing any more material from the case. The heads will still need to be opened up from ~98mm to ~101.25mm to take the top ends of the jugs, but that's worth it IMO for the thicker walls and increased sealing area.

If your "loose" case saver is serious enough to fret over, there are larger O.D. ones available - you could open up the hole and bore it for one of those, then machine it away where it protrudes into the cylinder bore. If this is a low-specific-HP build as I suspect it'll probably be fine as-is, but if the insert is ready to walk out and you just want to do something to improve things without a big investment, simply remove it and reinsert it with hi-strength Loctite; install an m10x1.5 bolt through a stack of washers and snug it down to 15-20 lb-ft, let it sit for a day or so to "glue" the insert in place under tension before you proceed.

BTW, whoever assembled that engine last should be hanged at sunrise - there's easily 10 times more RTV evident than has any business being used. A thin film. just enough to color the contact surface, is plenty. Anything over that just ends up as "worms" plugging up the oil strainer (or worse-yet, the passages & cooler if a strainer isn't in place)