i am new to the mini,
i would like to know what is maximum bore size you can go on a 1100 motor.
i have a clubman 1100
1310? 1360? 1380?
are the 1275 blocks the same as the 1100,other than bore size.
thanks for any help
found this website to be very helpfull

1275 and 1098 blocks are different. Maximum bore on a 1098 is generally +060 which is 1150 or so I think, or you can go to 1220 offset bored with Hillman Imp pistons, although it is not generally done these days.

Yes , the 1275 block is different to an 1100 or 998 block , they area smidgen taller (99% sure) and bigger internally (oil/water calleries out of the way) to allow the larger bores . They are virtually the same physical size but are too different internally .

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They are 10mm taller I believe, that's enough to allow me to fit my HIF carbie without it fouling the firewall. That's a good excuse to upgrade to a 1275 isn't it??

I've seen posted (by the Doc) recently that you can go to 1220cc with a 1098 block. That's with a 68mm bore size - about .134" over standard. Standard bore is 64.58mm. I believe you need to offset bore to get to 68mm - that is, bore the cylinder in such a way that you actually move the centreline of the cylinder. This is done as the cylinder wall thickness isn't constant around the cylinder. I don't know that you can go any bigger than 68mm bore/1220cc.
1275 standard bore is 70.6mm. 1098 engine has longer stroke than 1275, but the bigger bore allows the 1275 to go to 1330, 1360, 1380... Then some people start playing with stroke... There was a thread about that recently. But that's all based on a 1275 block.

The main reason for offsetting 68mm bores in a smallbore is they are too thin between the bores otherwise.
The outer bores (1&4) get moved outwards and the inner bores (2&3), together.

1275 blocks basically have bigger (and respaced) bores to start with, bigger (2" instead of 1.75") main bearings and as said they are taller.
Nothing inside the block is exactly the same except the dizzy driveshaft.

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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.

so i take it i need to purchase a 1275 motor to bore out to 1360 then.
what about the gearbox,will the 1100 fit onto the 1275 motor.
if i want to put 1 of these motors into my clumban can i use a motor from the later series motors.e.g.rover 1275 are these motors still classified as A series motors.

1098 block "can" go to about 1254 i think, which is imp +040, but its not a good idea

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speed costs....how fast do you want to go...

whats the differnce between a long motor and a short motor?
i see there is 1275 long and 1275 short.will these both fit into a clubman?
are the dimensions the same.engines are in the same place or not.

Long motor is complete block and head, short motor is jsut the blokc, complete of course (pistons, crank, cam....you get it)

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

Basically all it means is the long motor comes complete with head attached and short is without a head.. Same motor, same size..

As it's a 4 synchro Clubby box a 1275 bolts straight on.
yes a Rover 1275A+ will bolt straight on. I run a 1275A+ on a Mini-K/Clubby 1100 box.
With any 1275 motor on your box you will need an A series 1275 primary gear, its bore is bigger than the 1100 one you have.
A 1275A+ one won't work as their gears are finer tooth pitch.

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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.

somebody is selling a clubbie with a 1100 bored out to 1330,how can this be?
i thought you can't do this,or is the seller telling porkies.
www.ausmini.com/forums/viewtopic.php?t=33374

An 1100s block is a 1275 motor from the "morris 1100s", which was an actual car in the 60s.

It is not an 1100 block as you would think. Much easier to source (historically) than other local 1275 motors.

Cheers

matt

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68 Deluxe.... it's shiny..... I like shiny!!

yeah 1100 S, is a morris sedan not a mini, its a 1275, but on the back of the block is solid instead of the removable plates for the cam follower things (i think??)

Brenton