Rich G
Posted a lot
Keyboard Worrier
Posts: 1,059
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Jun 30, 2019 14:31:51 GMT
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Afternoon all; need some help from the BMC experts...
Will the head from a 998cc Mini fit on a 1098cc Minor block? Have a Stage 1 Minisport head which did about 3000miles on our old Mini (now sold) before it got replaced by a 1275 Metro lump. Thought it might raise the comp ratio if it will fit.
Thanks, Rich
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Jun 30, 2019 15:36:27 GMT
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I'm absolutly sure it will, i knew someone who fitted a 1100 head to a 998, so I would have to assume it works the other way round. I'm sure all A-series heads from 850 to 1275 can be swapped between engines, they will physicly fit, I think its all down to whether it will perform well or not.
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Jun 30, 2019 15:37:17 GMT
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Yes, it will fit with no problems. There may be minor differences to compression ratio but not enough to worry about. I did it the other way round (1098 head on a 998 block) and there was no change to performance. It was still slow  Edit: Depending on the valve sizes in a 12g940 (1275cc) head, you might need to pocket the block. |
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Last Edit: Jun 30, 2019 15:39:05 GMT by mrbounce
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Jun 30, 2019 17:34:43 GMT
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All the heads on the small bore A-series are interchangeable. So that's the 850, 948,997 Cooper, 998 and 1098. The 1275 and the other Cooper S engines (970 & 1071) are large bore. Those heads can be fitted to the small bore engines, but the valves hit the block on full lift. You can either pocket the block or recess the valves slightly. I've never done the swap, but there's a few people on the Morris Minor forums that have done it. Have a look here:- www.morrisminorowners.co.uk//index.phpor here:- www.mmoc.org.uk/Messageboard/index.php |
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1953 Minor (Long term project)
PT Cruiser
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That’s broadly true. But there is a big difference with the cooper 12g202 and 12g295 heads these had flat top pistons as standard so will need a good skim on anything else...
You can cheat with the 12g940 heads (1275) by sinking the valves into the head to avoid pockets.
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I once used the head off a 1098 Morris Minor on a much newer 1098 Mini Clubman just so I could keep driving it while the original head was getting work done. Huge difference in depth of combustion chambers. Minor head would produce a much lower compression ratio for this reason.
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merryck
Club Retro Rides Member
Posts: 477
Club RR Member Number: 9
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BMC A-series queriesmerryck
@merryck
Club Retro Rides Member 9
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Generally speaking if it fitted fine on the 998 block then it will fit fine on the 1098.
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