crank shaft swap

[grumpydad]

Hi
As i understand it
the crank on a 1098 has a longer stroke than a 1275
so is it possible to swap the crank and rods
to get a longer stroke motor
we are after more torque

Thanks

[bmcecosse]

Yes - you could use the crank from a 10CC engine (with the 2" mains). The rods are the same length for all A series engines (except the 970) - so you will need special 'short' pistons. It's not going to be worth it.......

[grumpydad]

why new pistons ?
I have messerd the blocks on the out side
with a rule and to me it looks like they are the same height
from the sump to the head

[bmcecosse]

Actually the 1275 block is some 3/8" taller (and longer) than a 948/1098 block. But no matter - that is taken account in the design of the 1275 pistons. So you now fit a longer stroke crank - it is going to push the piston further up the bore...and so it will stick out the top!! So - you need shorter pistons...OR... you could get shorter rods specially made - but now you are talking 'funny' money!!