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Mp850, if the crank you have would fit my 1275 (now 1380) I'm interested. Please email me and let me know if you didn't sell it to Steve already and how much you want.  
In case this doesn't work out, can anyone tell me what crank I should be looking for?  It seems the block I have is a 12g1279 pre A plus block, possibly from an Austin 1300 GT built between '71 and '76.  From what I can find either a 12g1505 or 12g1321 would fit.  The list on Mini Mania lists a bunch of cranks and the con rod journal sizes.  But nothing lists the main bearing size.  Are they all the same?  I came up with 2.13", is that normal?

John, I'm not sure about exact value. I'd think a good Metro 1275 block has a value around $500. Then add correctly carried out machine work. I'd rather buy the block and have my own machine work carried out. I currently have my 850 s and 998 s bored at one shop then load and move to another shop for hone and finish. First shop leaves .005 in the bore, second shop mikes each piston, numbers them and hones for clearance. I don't do 1380 s, I have a 1400 I'm working on only by special request. My personal driver is running a 1360 Cooper S. I have personally owned and driven this Cooper S block at std., .020, .040, .060 and 1360. This block has powered a 67 Cooper S to a 3rd. NE SCCA solo 2, 1st SE SCCA solo 2 and a couple of 5th s at National SCCA solo 2 over the years and several mini meet FTDs. I believe in getting the most out of my stuff. Steve (CTR)

MP 850 please shoot me an email about your crank. I have a job held up for need of a crank. Contact info in my profile. 

I have an Austin America crank and rods that I will be selling soon.  I am going to stick with the 998.  

So what is a bare 1380 block worth? Steve are you saying in the $800.00 - $1,000.00 range? (core bored to 1380)

I"ve got a 1300 engine with trans here in NY.  PM me from my profile if interested. Pulled from a running car but should be gone through to make sure you don't have to pull it after you install it.

That's what I thought.  So that means I can get a crank for a 1275, correct?  
Does anyone have any suggestions on a good place to pick once upon?  I'm finding ridiculous prices online.  I'm looking for an upgrade for my 998, nothing crazy.  I've seen the term fast road and that seems to fit.

Jamie

That is not offset bored.

Thanks Mike.

i was just looking at my new block and I'm not sure if it's been offset bore or not.  The distance between cylinders 1&2 and 3&4 are about 3mm and the distance between 2&3 are about 2.5mm.  Can anyone tell me if this is offset or not?

Jamie

there are 2 size blocks. small bore: 850, 998, 1100. and then there's the big bore: 1300.
Yes to your head question and the gasket sets fit all engines, but I would think you'd want a head gasket with copper.

I went and picked up the 1380 block.  Does a 1275 head work without being modified?  I imagine it would, but what gasket would I use?

Yes, it is an A series and looks like it was bored correctly. As for value, my machine shop charges $250. to off set bore and $100 to surface .010 to .015 and $1 per thou after that. I figure a 1275 block with caps that can be rebuilt to be worth $500. I believe my shop is still charging $100. per cyl. plus sleeve to sleeve back to std. I would suggest having the block and head set up for the extra stud and bolt and be careful to work out your compression ratio and order the correct pistons based on dish volume. Either AA, GT or A+ metro rods will work with a large journal crank. Sprite/midget of S rods if a small journal 1275 crank can be found. Like I said before an AA automatic core would give you everything needed other than pistons. Steve (CTR)

It looks to me that it's a 12g1279 and from my research it's from an Austin 1300gt.  Is it considered an A series engine?  Is it compatible with A series parts?  What is it worth?

I have added a set of rods to the for sale section.

I'd do a little checking with the owner or machine shop. If you are looking at a 1275 AA closed back block offset bored to 1380 and finished honed. With cam bearings removed freeze plugs out and main caps checked and a surface cut there is real value there. It would be nice to find out what pistons the block was bored for so the same size and brand can be ordered. If you could find an AA automatic core you would be almost home. Steve (CTR)

James,

 

I started my 1380 from a 1275 block and main caps. I'd say you need to plan to spend about $3k total pretty easily to build it into a running motor if you don't have anything else and aren't willing to steal from another motor (though not much other than accessories are useable).

 

Some folks consider it easier and better use of their time to pay a little extra to buy a whole unit.

 

-Cam

Thanks for the info everybody.  The guy who has it for sale, said it was a 1275 and he had it bored to a 1380.  When he got it back he realized it wouldn't work for the MG he was working on.  I had to admit I'm nervous about buying it.  I'd rather have a 1275 to build, but I can't find one.  It's just a block and main bearing caps, nothing else.  From my research it looks like it's going to be very expensive to get all the parts to finish.  I currently have a 998 that I don't want to steal parts from, because I want to be able to drive my car while building a new engine.

James

I call the Austin America/1300GT/1275GT/MG Midget blocks 1300 blocks. This way, 1275 means an S block, but not a 970 or 1071. 

Still, a Sprite/Midget block turned sideways uses an S dimension crankshaft and not a 1300 crankshaft. note the complexity. Ultimately it all comes down to determining what will be needed to build a decent engine. Often whatever big bore engine Spank has for sale at any given time is far better value than any core or partial core.

First question is - "What do you currently have?" the where is our starting point.  Other question would be which block?
Here I am asking 1275 A series, 1275 A+, or 1275 Cooper 'S block.  The assumption I'll make here is 1275 A series -
as shown in the picture (block has been offset bored).  It would also be a good idea to add the extra stud holes in the 
block.  The whole point of going to offset boring is to make it more evenly spaced.  In standard form the thickness between
the center cylinders ( 2 - 3 ) is 0.225" and 0.250" between ( 1 - 2 and 3 - 4 )  the bores are offset 0.010" from the
center and 0.015" towards the pushrod holes.  As others are telling you have it checked out ( something your machinist
will need to do ) 
As for crank there are several options I just used the one from my 1275.  Just as there are several 73.5mm piston options.