Minneapolis moline gb crank in a u

[Jeff mm-u]

Has anyone ever put a gb crank in a u block before? if so how do u do it? an any other good power tips would be helpful. thanks Jeff
 

[Blackland Dan]

I did. Have the machine shop off-set grind the crank to 6.2 inches. Make sure it is exactly 6.2 and grind the crank pins to 2.577 which is standard for the U. You can use the U rods. My machine shop ground mine to only 6" and it was very difficult for me to get it corrected. I had already ordered my pistons and I ended up having to mill the jugs down to make up for the quarter inch the machine shop cost me. Too much compression loss to leave it like that.
You'll have to change the crank timing gear. I forget what change I made, but someone on here will remember. Capt. Hookerus helped me with mine gear change.
 

[mmmmmmmmmmmmmmm]

You only change the crank gear if you are putting it in the later
tractors like a 5 star or M5 or 670 then you use the gear off an early 605 or 425. You can only offset grind the stroke about .150 unless you go undersize on the U journal.
 

[Blackland Dan]

Well then I guess my machine shop did me a favor. That explains why I had to change my crank gear because I put it in a 5 Star. Question mmmmm, would he be able to use the GB rods if he decreased the compression height on the pistons? Important point for me as it will change the way I do things from now on.
 

[mmmmmmmmmmmmmmm]

No the G rods are much too long. A viable alternative is a Detroite inline 71 series rod it is a little narrow but the same rod brg size as a G 2.75 and is 10.125 inches long. There are some international v8 power units that use a 4.625 piston that will work with a 6 inch crank and this rod. They are even available in .060 oversize.