300/440/550 Js440 block

[Aimable455]

Hi have just discovered a chunk of metal missing from the piston housing inside my block so require a new one.
i am in the middle of looking at another on eBay however it does not look the same as mine.
so my question is are all js440 blocks the same throughout production or are there different types.
this is the item number on eBay 261055653779

Cheers Steve

 

[screaming440]

there are two different cylinders for the 440, the early ones up to about 79 had an aluminum cylinder the newer ones are cast iron.

the cast iron ones lool less bulky and have two less head bolts.

they are interchangeable but if you put the iron on the aluminum cylinder you have to machine two holes. toe other way you just tap the extra holes and put a brass plug in them.

 

[Aimable455]

Thanks for your reply screaming440 once posting this I looked into it and found the answer you gave about two different types etc.
i had the cast iron block, so if I bought the alloy block I would have two plug the two extra holes as not needed or is it the other way round,
i would be replacing my broken cast iron block with alloy version

 

[screaming440]

if you have the head off a iron motor it has two undrilled bosses in the head. those have to be drilled for it to fit the aluminum motor.

 

[Aimable455]

Thanks for the heads up, hopefully got a 550 block with pistons now for £65 gbp, trying to find parts for this ski over
here is a pain
Cheers Steve