Norton Commando 750 Engine Number

I need some help here gents. I just purchased a 1975 850 mark 3 commando in large lumps plus 3 large boxes of 750 commando parts. Also part of my purchase was a complete Commando 750 engine in the cradle with swing arm ,gearbox and primary all in one piece. The flanged black barrel has the cast in #24237 and the gearbox is numbered 040122. My problem is there is no engine number under the barrel flange and even with close inspection the crankcase surfaces appear not to have had any alterations i.e. numbers ground off or weld overlay etc. The cast surface appears to be normal in texture on sight. Did Norton ever provide unstamped cases for any special reason in any instances or do you feel i may have a stolen motor. I also noted there are no numbers or codes on the top of the rocker box casting. Thanks

You may find some reference here MK3 frames, heads etc

http://atlanticgreen.com/norton.htm
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thackero said:

The flanged black barrel has the cast in #24237 and the gearbox is numbered 040122.

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Both are 'casting' numbers, not actual 'part' numbers (so you won't find them in the parts lists).

'24237' would be normal for a set of 750 barrels and '040122' is found on the majority of pre-Mk3 gearbox castings.

thackero said:

My problem is there is no engine number under the barrel flange and even with close inspection the crankcase surfaces appear not to have had any alterations i.e. numbers ground off or weld overlay etc. The cast surface appears to be normal in texture on sight. Did Norton ever provide unstamped cases for any special reason in any instances or do you feel i may have a stolen motor.

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Replacement crankcases were normally supplied without any number, so the original crankcases were probably replaced or, the engine could have been built up from a mixture of new and old parts? If as you say, there's no apparent evidence of tampering with the number pad then I wouldn't worry.

thackero said:

I also noted there are no numbers or codes on the top of the rocker box casting.

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That isn't particularly unusual either, cylinder heads don't always have the 'RH' stamp.?

I have now found another number on the gearbox casting 138458. Still cannot find a engine number but continuing my research.