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1275 "12H" Engine - Ado16 Or Not?


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#1 Dunk1302


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Posted 08 October 2020 - 09:41 AM

Morning all...... I'm currently rebuilding a 1275 engine to transplant into my 998 mini. I've been trying to narrow down it's age, to help with the timing settings, etc but so far the best I can manage is "maybe early 70's".


The engine prefix is 12H159C, and all the online resources say this is from an ADO16, which makes sense - it came with a remote gearbox, which I've swapped for a rod-change to match my car.


However..... here's the confusing bit - from what I've read, the early ADO16 engines were "12G", a de-tuned Cooper engine, and the later ones were "12H"..... BUT these 12H engines were (I believe) 11-stud, while mine's only got 9


Could this be from some other related vehicle? Maybe an Allegro or Marina (post-ADO16)???


Any help narrowing down it's birthday is greatly appreciated!







#2 GraemeC


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Posted 08 October 2020 - 09:49 AM

Your belief about ADO16 12H engines being 11 stud is incorrect - some may have been, but they weren't all

#3 Dunk1302


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Posted 08 October 2020 - 09:57 AM

Ahhh... thanks Graeme - that threw me, when I read it.


Are there any other tell-tale signs that might indicate it's age? It's a pre-Valeo clutch and there's no timing-mark pointer on the timing cover (just the flywheel marks)





#4 nicklouse


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Posted 08 October 2020 - 10:05 AM

159 is just an ADO16 


the G versions had S rods and were there till about 71.

#5 Spider


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Posted 08 October 2020 - 06:13 PM

I would actually say that the majority of the 12H engines were 9 stud with a few 11 stud types made for the likes of the 1300GT.

#6 imack


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Posted 08 October 2020 - 06:33 PM

Your engine code and remote box indicates a pre 73 ADO16.
Only the very very early ADO16 engines (1967) had any S parts but they still had the small valve 9 stud heads.
Only the 1300gt, mg 1300, and probably the wolseley and riley 1300 versions had the 11 stud big valve head with innocenti rods and crank and higher cr and twin carbs.

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