8 replies to this topic

[1968andyf]

Looking to short stroke a 1275 crank to "s" size big ends,anyone knows the shortest they grind to. And with a 74mm piston what capacity this would make.

[Tupers]

With a 12G1505 crank you can go down to 79mm or up to 84mm nominally.

A 79mm stroke with 74mm bore would get you a 1359cc.

[timmy850]

You'll also need to adjust something for the reduced height of the pistons, like a big skim on the block, longer rods or custom pistons. 

 

I've got a 70mm South African crank which will need some serious skimming to get the pistons flush

[OzOAP]

You'll also need to adjust something for the reduced height of the pistons, like a big skim on the block, longer rods or custom pistons.

I've got a 70mm South African crank which will need some serious skimming to get the pistons flush

I have some 6.25 length rods

[miniGTS]

You'll also need to adjust something for the reduced height of the pistons, like a big skim on the block, longer rods or custom pistons.

I've got a 70mm South African crank which will need some serious skimming to get the pistons flush

That's the SA 1100 big bore crank 12G2827.

Edited by miniGTS, Today, 01:40 AM.

[timmy850]

I have some 6.25 length rods

Thanks, I’ve checked the measurements and I’d need closer to 6” rods in order to get close without a huge skim. 6” rods are available, but mostly with different pin sizes to suit the reduced height pistons which wouldn’t work for me

That's the SA 1100 big bore crank 12G2827.

Yep, I got it posted out from SA. I had it reground at a local crank shop and he measured it at 70mm

[miniGTS]

Just as a matter of interest, what's it cost to ship from SA to UK?

I have one in storage and one in my car. They're not very popular here.

[timmy850]

Just as a matter of interest, what's it cost to ship from SA to UK?

I have one in storage and one in my car. They're not very popular here.

Well it seems now that I’ve looked I’ve had this in various garages since 2017!

Back then it was R690 for sea mail, and it took about 3 months to arrive to Australia. It was better than R3900 for air post.

If you are interested in selling some to the UK there are guys on the Mk1-forum who love them as they’re a much cheaper option to build a smooth 1071 Cooper S type engine

[1968andyf]

Thanks for your answers it's give me some stuff to check and measure.