missing block case

**yukoner** · 12-10-2009

Recently, a Yamaha 40/50 block came up on ebay (bored over) with lower case missing. I intended to bid on it but missed out. It came with the over size pistons to match, so it was a great deal if only for the pistons. The question is, can one just mate another half to it? I have other blocks with areas missing from thrown rods, but never tried it for fear of losing good parts.

**88workcar** · 12-10-2009

as long as it is 40/50, any front half will mate to any block, and any one of them will mate to any midsection as long as it is all 3 cyl stuff. If that answers your question. Your question is somewhat confusing

**Ron Hill** · 12-10-2009

Can a different chest fit on a block. We have done this hundreds of times. We take any alignment pins out. Tighten the chest slow while turning the crank with the flywheel and feel for tight spots. They will run with tight spots, just won't run as fast...trust me.

**Fast Fred** · 12-14-2009

it most likely will not work, another 40/50 front 1/2 will bolt up, but will most likely lock the crank up when torqued up to spec. i've tryed it many times, it's never worked on a yamaha for me.

i gots a 40/50 case, 50buck + shippin, late model.

**Ron Hill** · 12-14-2009

Hey Fred,

You ever use a brake hone ? We've run a brake hone through the block/case assembly when we have done this. If you mess with it LONG enough, usually you can get the tight spots out. (I've done this on OMCs and Mercs...and Yamaha V-6's..).

We used a brake hone even after welding a few holes up in a block.

We have also filed the cases half to tighten the mains on in older Merc to tight the reed blocks, as read blocks will "DANCE" in mismatched blocks....

My dad has nearled reed blocks to keep them tight in our old motors...

I enjoy your stuff here, Fred. Keep it up!

**yukoner** · 12-14-2009

Fast Fred
I tried to PM you but your inbox is full. I'll take the block but am wondering if the money might be better spent on you building a motor for me.

**Pop990** · 12-14-2009

on the 45 motors, I have a couple dozen extra cases and have always found one that worked nicely although sometimes it was 1 out of 20. my 2 cents worth. BC

**Fast Fred** · 12-14-2009

can't say i've ever used a hone on the line bore, could work

i've never had a yamaha 3cyl work without the factory front 1/2.

the case need to be bored i think, could port it for ya, finger ports yes?
made room for ya in the PM box

I enjoy your stuff here, Fred. Keep it up!

thanks

**88workcar** · 12-14-2009

Is he asking to use a differant type style brand ect, or just a case / front half of the same style and type just not the matched set?

**fyremanbill** · 12-15-2009

I think he is aking about using a case that was originally machined/matched to another block. I've mixed Merc v-6 stuff with no problem, but each motor is different.