I have had an old 1100 engine and gearbox sitting around that I have used for parts when building up my project 75 Leyland 1275 Mini. Now my attention has turned to the 1100. I stripped it and found that it will need a full rebuild including rebore because the top has disintegrated on No1 piston. I am looking at a standard build but have a few questions.

The bore measurement is worn to 65.5mm currently. What size overbore should I go for? When the head is reconditioned and hardened valves seats added, should I try to retain the same valves or increase size? I will be running an 1&1/2 SU, standard cam, standard manifold, Perry 3to1 extractors.

Any advice would be great, also any recommendations for machinists in the Gold Coast area. Plus best place and price for the pistons, rings and bearings? Thanks.

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1975 1310cc Street Mini Custom
1974 Leyland Mini daily driver
2008 Cooper S R55 Clubman

It's hard to know how much to overbore without seeing the damage to the top of the bore. You might need to get a shop to have a look at it first before ordering the pistons. 65.5mm is +040 over already (assuming it's measured correctly) so you don't have a huge range of larger std type dished pistons.

+060 pistons
http://minisport.com.au/1100-060-piston ... et-hypatec

Finding another 998/1098 block is very easy and cheap..

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I measured the bore in No1 with a set of verniers. From what you said, if it has been bored out to +040 already I might be better off getting another block and caps.

The crank journals for the conrods measure 41.2 and the conrod bigends are fitted with bearings stamped 'ACL 010 2201 23JU89'. Are all 1100 crank main journals the same? Just wondering if I can reuse the crank and refit with new bearings in another block.

** Just found on the crank written in white '010' **

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1975 1310cc Street Mini Custom
1974 Leyland Mini daily driver
2008 Cooper S R55 Clubman

Go & have a chat with Nathan at Works by Wilson/ Wilson Engineering in Southport.

Brad

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During the day I work on English designed cars & on my own time I work on English designed cars....

I would bore it to +.080" and use Graham Russell's flat top pistons. They are stronger than Hypatecs (which have 3 compression rings and weaker ring lands).

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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.

If you need a new block I have one and am in the Gold Coast as well have other bits and pieces to

Thanks Smoot, i will let you know. I am going to take the block, crank and rods/pistons to get checked and see if machining is okay. I will definitely be needing one conrod for the busted piston.

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1975 1310cc Street Mini Custom
1974 Leyland Mini daily driver
2008 Cooper S R55 Clubman