Is it feasible to fit a small bore head on a big bore (1100S) to make the engine "look" like an original 850.
I realise it would need chamber, valve and port work, but can you still get the original 1275 power ?

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Find a job you love and you will never have to go to work !

To use a smallbore head on a 1275 gasket, some water holes in the head need plugging & redrilling. See GR's project 68mm story on his website. I have just done this to a 202 head for a 68mm bore 998.
Yes it can be ported to flow like a stock 940 head.

(Edit) Why do this??

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Why
The most obvious thing about a big bore is the position of the thermostat housing.
If I have a small bore head on the big bore in my 850 it will "look" more original.
At a quick look in the engine bay it will look to the untrained eye like an original 850.

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Find a job you love and you will never have to go to work !

Sleeper 850

The pro's will quickly look further and discover what's going on, but the uninitiated might not

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Find a job you love and you will never have to go to work !

Make sure the head isn't decked much, these old smallbore heads are all corroded inside and the deck is much thinner than a 1275 one.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

You going to run a single HS2?

I'd be more inclined to keep the bonnet closed and run a real free flowing 1275.

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

1275 with an HS2 is a waste of time,IMO.
But it'll climb hills good.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I would go Twin HS2's and a Sticker on the rocker cover that reads "Sports M 850"

I put a 1098 crank & pistons in a Sports 850 back in the 60s. With stock head & cam it didn't rev hard, but boy it had some torque. Good sleeper.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

My first car was a 72 Clubman with a tired 1098. The car was 100% stock. I was able to pick up a reco 1330cc that replaced the original. So I was running it with the original carb, that is a HS2 and exhaust.
After about three months I saved up some money and then put on a set of Sprite SUs and extractor exhaust. It had twice the power!!!!!

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

So you think that the thermostat position is more noticeable than a big carby or an engine number starting with a 12?

Does seem a bit crazy to me .

It'd definitely be different.

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WD40'll fix it!
If it don't, use a big hammer!

maybe it will start with a 9?

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

Well, I've gone to the trouble of replacing my rod change box with a 4 synchro box and 850 diff so that I will have a Magic Wand gear lever so the interior looks more original .
Was wondering what I could do in the engine bay to make it more 850ish.
I'm not after total originality, just a bit more like an 850.
It will still have the 1-3/4" SU and extractors (like a souped up 850) !

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Find a job you love and you will never have to go to work !

just go with the full bore 1275

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