I have recently got a 1275 short motor. 11 stud 12G940 with big valves, 1100S block, and the crank has never been ground since the factory (ive measured 5 thou under standard in the worst spots).
It had some decent +0.060" AE pistons, one had some weird pitting around the rim and a big burnt hole down the side etc... turns out its also damaged the bore of the respective cylinder. measured it to be around 0.35mm deep, so im thinking ill have to go to 73.5mm bore to clean it up properly. Do the bores need offsetting for a 1380?

With camshafts im not sure whether to go a 276 or 286 megadyne, vp7 or re-13 -what have other people experienced. Also how much should i expect to pay?

You can bore it to 1360cc (73.0mm) leave the 1380 for next time.
I got Hypatec pistons this size from Ken Nelson, at www.miniauto.com.au/home.htm

Price- under $290/set, landed at my door.

Graham Russell has stocks of them too. Popular for the racers among us..

re the cam- you won't better an RE13 for road use, or price..
It's the best fast road/track cam I've used, and I've run many!

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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.

Could you please tell me the part number for those pistons?
My local engine builder can get hypatecs in so ill see what kind of deal he can do me. Im assuming the price for a set included rings?

thanks

It should include the rings.

Stick to 1360 or 1330 that way the block can survive another rebore in 5-10 years time to 1380 (which is maximum). Anyway the real improvement will come from porting your cylinder head so I would spend some money there.

What carb are you planning to run?

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Lillee - 1969 Morris Mini K

The damage to the wall may mean ill have to take it out to 73.5- its off getting dipped and checked at the moment. I would prefer 73mm for the extra wall strength and room for another rebore. Ill just have to see how things go.

Im currently running a 40 DCOE on my 1100, Im thinking i may have to go a 45. What kind of power should roughly expect from a 1360 with Mk1 's' head (big valve) with standard porting, re-13, manilflow mid bore LCB?

90-100hp? depending on intake manafold and carb setup.

I would go the 45 if you can get your hands on one. I am running a 45 on my 1098 right now. 34 or 36 chokes.

What conrods are you going to run with the hypertecs out of curiousity? Standard 1100S ones? (Which I think are Cooper S rods)

Get your flywheel ground to lose some weight and balance the crank, flywheel and pistons too.

What box do you have? tell me it's a remote! are you getting the box rebuilt too? better off doing that. Run a cooper S first motion gear if you are. What diff ratio do you plan to run?

Sorry about all these questions, I am currently rebuidling mine and want to compare

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Lillee - 1969 Morris Mini K

No they are the large journal rods, different to the 'S'. I dont think they are any different in the small end.

No i have a rod box, its a '76 clubby. I want to rebuild it but that will cost even more money. Ill see how much is left over after doing the engine. Diff atm is a 3.44, i have a few lying round and also a 4.22 or something stupid like that out of a morris 1100 box. What did the original magic wand 850 boxes have? because ive got an 850 long motor also.

What compression do these hypatecs produce on a std engine?

850 box? Forget it mate, they are magic want gear stick (really long stick all the way from the box) hardly what you'd call performance I don't think they'd handle the torque that your engine will produce.

They hypertecs are pretty good for CR, what CR are you planning to run?

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Lillee - 1969 Morris Mini K

No, no lol i wasnt going to use the actual 850 box i was just thinking the diff might be a 3.6 or 3.7 and i could use it. I would never run an original 850 box, they had the magic wand plus the brass synchro cones that wore out quick. sorry should have made it clearer.

I plan to run 9.5-10:1 comp.

My mistake probably.

Naah just run 3.44 diff. If you go to 3.66 or whatever you might need to re-gear your speedo to suit else it will be wrong. Besides, 3.44 and your planned beast of a donk will be sufficient for take off You'll get better economy on the open road and higher top speed.

Who are you getting to build all this if I may ask?

If the rod box is in relatively good nick then it may be ok, if I were you i'd rebuild it. I don't like the sound of building a brand new engine only having to pull it out again after 30,000 miles or whatever cause the box has gone etc.

Think about a centre oil pickup too. They're not cheap but I think they're worth it for 80+hp cars... you never know when going around those corners...

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Lillee - 1969 Morris Mini K

At this stage i am not sure about who will do the work. Boring and grinding ofcourse im getting done by a professional. Assembly i might do myself or just get it done by someone if it isnt too expensive. For the hard work and chemical cleaning im getting QIM in Qeanbeyan, NSW to do it. I am in Canberra so its close and hes had a fair experience with mini's before.

Cool, keep us posted on your progress

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Lillee - 1969 Morris Mini K

Christoph,
P/no for the Hypatec 73.0mm pistons: PAU127540941H
They come with a Hastings (USA) ring set.
C/R.. I think around 10:1 with a stock head. Mine is running 10.7 now..

850s had a 3.765 diff, same as Mini Deluxe. Bit short unless you are just doing motor sport.
Mini K/Clubbie 1098 got a 3.647, which is what I stuck in my new 1360.

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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.

Do you get many problems with pre ignition? im guessing you just run optimax/vortex 98 sorta fuels.

thanks for the p/no.

No preignition with 98 octane, Mobil or BP.

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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.