Evaluating '71 engine cases

In case anyone can help....

I have these cases numbered 20M3S 146219, which is mid '71 from my research. Note, if these are 'hot' I will return to rightful owner, I have no knowledge of them, they came with my '66 N15CS. To my untrained (at least Norton-wise) eye look decent, but... I can see they are a bit scuffed up from some mishap inside (pic 4) and there is a Heli coil in the center hole of pic 8. The gasket surfaces look decent, some minor gouges only. The threads look quite good overall, but one looks a bit suspect, it's at 4:00 in picture 1.

They sat in a garage for years and all replaceable wear items will need to be updated I'm sure.

I will be selling them, just want to know what to look for, to see if they are goners or have value to someone.

I hate these 'what are they worth' type threads and I am not asking for dollar values. When I do sell them I will give a great deal as I always do. My goal is to be able to represent any issues that I may miss - what should I look for to see if they are usable or not?

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They look usable to me.

I'm confused about the placement of the engine number. I thought all with 20M3S were marked in the curved part in the front left of the engine. I'm sure L.A.B. will know about that and let us know about that.

It was moved to that rearward location in mid earlier 1971. ( I have both types)

Time Warp said:

It was moved to that rearward location in mid earlier 1971. ( I have both types)

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I've been looking around. 143xxx front 146xxx side. Can you get it any closer?

marshg246 said:

I've been looking around. 143xxx front 146xxx side. Can you get it any closer?

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Get what closer?

gpzkat said:

Get what closer?

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What Greg means is closer to the serial number where the 20M3S prefix and serial number were moved to the flat area, however, the actual number where this occurred isn't known but the stamps on your case appear to be genuine and are in the correct place for (20M3S)146xxx.

It does look like the engine had a blowup, likely a rod, but the cases still look usable to me. I would check carefully for cracks on the drive side around the upper rear part of the case, but I don't see any visible in the pictures.

Ken

I have seen cases marked up inside like this from a cam follower shedding its Stellite tip (offending article was still in there - what a mess!!).

I cleaned them up with a flap wheel on a die grinder.

Thanks all. Well, it was late last night and I was busy with some other stuff as well, and I completely missed this impact area on the case.

I also had a set of barrels that in my ignorance I discounted as being paired to this case due to level of damage they sustained, but I suppose iron being brittle...

That case half looks repairable, the barrels..... not so much

Ouch!