Con rod bushing

[Nicolai-Denmark]

Hello
Im building a Stroker M42 with the M47 88mm crank, 135mm M50B25 NV rods and the 86mm S50 pistons.
But ran into a problem - The wrist pin for the S50 pistons is 21mm and The M50B25NV is using 22mm.

Anyone knows where i can buy a bushing that is 1mm thicker or what have people done when running that combo?
If im correct the new bushing should be 23mm on the outside and with a 21mm hole and 22mm long?

[Warsteiner]

Nicolai....please do your math. If you have no other modifications, then you will have a very low compression build. I don't have a compression calculator but I don't think this will work for you.

Please have your machine shop or your builder go over the build with you. Have them do all the math with you.
Measure all your parts. Then measure them all again to be sure.

Here is a quick look:

Here is a stock M42: 212-40.5-139.85= 31.65mm CH

US S50 piston Compression Height (CH) 32.8mm
Euro S50 piston CH 31.6mm

212-44-134.85=(33.15mm needed CH for M47 crank and 135mm rods).

Both of your piston choices are too SHORT and sit inside your bore.

I wouldn't worry about your 21mm or 22mm wrist pin issue until you figure out your piston and rod issue first. Your machine shop can easily take a 22mm bushing and make it 21mm by honing it for you.

Good luck!

Cheers,
~Ralph

[Nicolai-Denmark]

No worrys!
Going for the B18c Rods instead and shaved a bit of the Euro piston after i found out my self, by reading one of your answers to another person where you described the formula for calculating the DCH 
They also look to be a bit more slim and lightere than the M50 rod?

[DesktopDave]

I just went through your build thread, holy moley!  That's incredible! It's nice to see an E36 Individual too, there couldn't have been very many of those built.

Sorry to thread-jack, just had to pass along the compliment. Please return back to your engine build.

[Warsteiner]

Not sure how they compare to the M50 rods but the GSR rods do give you the 21mm small end that you were looking for:-)
Make sure to keep some pocket depth on the piston tops for future use of higher lift cams.

Cheers,
~Ralph

[Nicolai-Denmark]

I just went through your build thread, holy moley!  That's incredible! It's nice to see an E36 Individual too, there couldn't have been very many of those built.

Sorry to thread-jack, just had to pass along the compliment. Please return back to your engine build.

Thank you!
Yeah it was my first car to but back in the days and first after buying it i found out it was an Individual with lsd and ofc the pretty Dakar colour.
So it got a pretty big value to me cause of its was my first car and its a Individual, thats why i startet to restore the body so i can be good as new!

[Nicolai-Denmark]

Not sure how they compare to the M50 rods but the GSR rods do give you the 21mm small end that you were looking for:-)
Make sure to keep some pocket depth on the piston tops for future use of higher lift cams.

Cheers,
~Ralph

Yeah so it both have the 21mm small end and right lenght.
But isn't the GSR rod a press fit?

[Warsteiner]

I didn't do GSR rods. I did aftermarket that were to GSR specs.

Cheers,
~Ralph

[Nicolai-Denmark]

Just bought some MANLEY rods