G12 parts interchangeability

[alanengineer]

I have acquired a 1959 G12 engine that seems to have been built up from a 65/66 engine. It has a 59 crankcase and late cylinder heads with the horizontal fins. It turns over, but i have not gone any further yet. I have the original, damaged, late crancases.
The engine is in the frame and it was my intention to just give it a once over and a coat of oil on the outside and run it, or see if it will run. But, i understand their are a lot of differences in the internal bits of the engines. I was told it has run in its present state.
Is it technically possible the marriage of the two engine will work or should i strip it and build it in the original crankcases and be confident the job has been done properly. Assuming the welding of the cases is good.

[teebee67]

Sorry I can't really help with your query but, should you decide to sell the motor, please let me know.

[Duncan]

Generically speaking providing the top end matches it should not be an issue, its pistons and heads that you cant mix and match pre and post 1960, peer down the plug hole if you piston is flat topped you should be good to go.
Depending on how late your top end is the engine cases may have been taken out to accept 3/8" studs (introduced 1964) alternatively stepped studs may have been used instead of re-tapping the crankcases, if not that may allow some movement and a potential blown head gasket at some point in the future but it is not a certainty, the original crankcases should soon tell you what size they were/are and you may be able to measure the studs through the fins (I have never tried to do this though so don't know if its possible).

[G15 Roy]

Also interested if for sale

[alanengineer]

No, not for sale.

I am going to take a head off and have a look. Im also going to get the original cases leak checked where it has been welded. Looks a better than average job and its above 1/2 way up and behind the primary chain case, so a rebuild into its original cases is a strong consideration

Alan

[teebee67]

Shame it's not for sale (it wouldn't be if I had it either), good luck with the build.

[Duncan]

No, not for sale.

I am going to take a head off and have a look. Im also going to get the original cases leak checked where it has been welded. Looks a better than average job and its above 1/2 way up and behind the primary chain case, so a rebuild into its original cases is a strong consideration

Alan

Dose it still have the boss for the primary chaincase stud?

[alanengineer]

dont know, why?

[alanengineer]

dont know, why? Oh, i think i hve worked it out. Will have a look in the morning. I think the welded hole is higher than that

[Duncan]

dont know, why?

Its usually the boss that gets broken off when the final drive chain snaps.