The difference in 1275 blocks

[craig bryant]

I know that this subject has been brought up before, but I need to ask again. What are the differences in 1275 blocks between the supposed standard and Minis? Can both be used equally well for an LP motor, or is one better than another? Thanks in advance for all opinions and advice.

Craig

 

[joecam96]

The 1275 Mini block (Cooper S, Austin America and A+) have a thick flange where they mount to the Mini gearbox, which helps make them stiffer. The A+ is stiffest with even more webbing on the outside of the block. The oil pick-up hole is smaller in a Mini block and will require some machining. There may be some other differences, I think that you need a different rear main cap.

 

[glenwood]

lookiing at them side by side today the sprite 1275 has more holes drilled into the block on the flywheel end ......

 

[Acme Speed Shop]

A FWD block can not easily be coverted to RWD, it take the main caps form inline bolck, drill and tapping for the front rear engine plates,, they also have different crankshafts. I see no reason whatsoever to convert a FWD block to inline RWD.

As far the inline RWD 1275 blocks that came in the Sprites and Midgets, there were also thin and thick oil pan flange blocks, the thin flange blocks were the early ones, and had no pie shaped opening under the center main bearing saddle in the block, the later blocks had a thicker oil pan rail flange and have a opening under the center main saddle, for building a race engine, especially a LP 1275, none of this matters.

The only thing I ould concern myself with when looking for good 1275 block core, would be to make sure you don't have a factory sleeved bock, they did not step the sleeves, they hang out the bottom of the bores, and they were incredibly thin, making them useless for about anything, other than making a 1380cc street engine.