As per the title, are there any advantages in using an A+ 1275 block over a pre A+ (non S) as the basis for a hi-po engine build?

um.. The A+ blocks are heavier !

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
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Some might think so, but I don't.
Many/most A+ blocks had porous castings, were sleeved, and the water jacket not concentric with the bores....
[edit] I dunno if they are heavier, they put ribs on the outside and thinned the block in other places.

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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.

No problems with my A+ blocks, but they were post 1990, if that makes any difference.

all the big power engines in UK use A+ blocks.... shouldn't make a scrap of difference

Supposedly the ribbing is meant to help with torsional stiffness, but I guess that really depends on its intended use.

Most A+ blocks have done far less kms/"work", and therefore aren't as flogged out.

"Some" blocks were porous; these were lined from the factory.
If you have one of these blocks and need to bore oversize - larger than the liner/sleeve allows, you'll need to go oversize with these too and that will be an additional cost of course.


What are you going to be doing to the engine?

If you are going for big power try and get a large journal crank, there stronger than most others simply because they are thicker where the bearings sit. Other wise I don't think any type of block is better than another.

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Respect mine and I'll respect yours.

Big journal 12G1505 (late 1100S, 1275LS etc) cranks are more likely to crack than the small journal ones, their fatigue life improves if you grind the crankpins down 1/8" and put decent radii in them, so they can flex.
ie, stroke that sucker (but crack test it first- many are cracked already).

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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 have a 1100s block at the moment. Planned build is 0.020 over, 70.2mm south african crank, bmw rs head and turbo. Could say it will be slightly modded.

Sounds like the block i have will be ok then...

Nothing wrong with an 1100S block for getting high power.

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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.

hee hee,,, they use them simply because they stuffed & sold & ruined & thrashed all the early ones they had & hardly have any early strong ones left now so of course they`re going to use A+ blocks for their race engines,,, they have no choice


& yes , if an A+ """isn`t""" sleaved,,, then it probably should be

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Didn't the A+ motors have timing chain tensioners too?

Wouldn't this be a... plus?

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Baby I don't care

Useful for taking up the chain slack when you line bore an A series. Yes!!

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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.

Matt, does this apply to all A+ blocks, or just the early ones?

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Steve

i don`t trust any "Non-Sleeved" A+ blocks to be honest

like i said earlier & have always said--> if they are not sleeved then they probably should be

even if they look great & have been running well for years & years,,, & then you go & bore it out,,, & then it shows up it`s porosity...(or rather it "May" show up)

don`t get me wrong,,, i`ve seen heaps & heaps of these things, we used to import hundreds of them every year, pallets & pallets of the damn things,,, so i`ve seen (& still do see) my fair share of them,,, but you`d "RARELY" see a porous 1100"S" block hey?

& yet (of the non-sleeved A+ blocks) i`ve seen almost as many porous A+ blocks than non-porous A+ blocks (almost)

nothing really wrong with sleeving them now-days except for the cost

we are running out of quality 1100"S" blocks & so the A+ blocks will have to be used ... & if they have to be sleeved then so be it,,, at least then we can use them

but yes,,, i must say,,, i`ve seen less problems with the later blocks

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.