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I recently got a 1963 Morris 850 again and am thinking about what bolt on mods I can do to give it a bit more power. I've read on here about people using 12G295 heads and so forth. The motor will come out for a clean up but I'm not planning to go as far as cam changes, boring out the cylinders and that type of thing just yet.

I have a small bore LCB exhaust manifold lying around and was thinking about a period tuning inlet, maybe some head work etc.

Any ideas welcome.

The difficult bit with 295 heads on 850s is having the CR right. I'd start with a 202 head, large bore pressed steel rockers (double check lift clearances) and twin HS2s - this may be the cheapest way to improve it, just don't expect it to perform better than a 1300, it's still an 850.

Be careful of pushing your 63 850 block. They only have one cam bearing, at the front. The other two run directly in the block and it will wear out. When the rear bearing wears out, the narrowest one, it breaks the oil pump drive.

Thanks for the replies so far. Yes, I don't expect to create major performance and I don't want to go so far that I damage anything. I mainly want to be able to get up the hills on the way to work a bit easier. So is the 12G202 head a straight swap if I keepe thechambers standard?

The original head had chambers of 24.5cc or thereabouts
The 202 head has about 26.1cc.
Using the 202 head, the compression will drop about 0.38 points - for example from 8.3 to 7.92
The 202 head, having a chamber surface area of 25.1 cm², skimming 0.63 mm will remove the discrepancy. Skimming though is normally done in 0.25mm intervals and skimming 0.75mm will give 8.38:1 compression.

Just a rough guess.

Thanks Frogeye. I obviously have a bit of reading to do and thanks for providing me with some of the details. The main aim of this thread is to get a feel for what you guys think a good general direction is.

Hi there,

Pretty sure there was a good thread about this not so long ago on the forum....

Ah, yes found it: viewtopic.php?f=3&t=6846 It also contains a link to another useful thread on the subject.

I can't comment much because my way round the problem was to cheat and fit a 998cc Cooper engine!

Hope that helps!

Chris