Farm Equipment - 8070 crankshaft

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8070 crankshaft

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=12837
Printed Date: 31 Jan 2025 at 8:08pm
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Topic: 8070 crankshaft

Posted By: Lynn Marshall
Subject: 8070 crankshaft
Date Posted: 23 May 2010 at 2:09pm

I'm working on an 8070 with a bad rod journal.New crank is extremely high and used are in short supply.Local salvage wants to sell a complete engine out of N series combine.This counterbalanced crank was only used in 7080,7580,8070,4W-220,and N5 N6 combine.Opinions -anyone. Grind it,keep looking for used[anyone have one],roll the dice on the combine engine.Also,would you be afraid of a standard crank like out of a 7060 at a few hundred higher R.P.M. Thanks for any input.

Replies:

Posted By: DrAllis
Date Posted: 23 May 2010 at 7:25pm

If it has discolored the journal (even tho it might not be cracked) it has taken out some of the hardness and will someday fail on that journal. Imagine taking a grade 8 bolt and heating it will a torch until almost red and letting it cool off.......it probably isn't gr 8 anymore.

Posted By: Kcgrain
Date Posted: 23 May 2010 at 7:40pm

The standard crank, does not have the counter weights, other than that they are the same, Like the Dr said i wouldnt try to reuse yours if its blued or ground in to. You dont need RPM to make the 170 hp of a 8070, and in my opinion the only reason they were counter balanced was to make up for the poor fuel delivery of rotary style pumps at high HP applications. An inline pump evens out the balance between the cylinders, which doesnt require the counter balancing to keep the engine running smooth at Hi RPM and fuel delivery. There are used counter balanced cranks available at salvage yards, like all states ag $850, its only 50 bucks more than the standard crank, and thats already ground and or polished.Before Id buy a crank, and over haul that motor I would first determine why the rod spun, and take care of that issue, like was the radiator plugged and it was over heating, is the valves shot so you have uneven cylinder pressure, is the injectors any good and in corretly, is the pump operating correctly. A cheap over haul of a crank , piston and liners will not be cheap in the long run.