Combines 670I under haul IJ

My dealer 2 years ago didn't have much of a choice for parts, only one supplier at that time for the proper bearings for my engine. But the engine is identical to the AC8000 engines with two oil sumps. I had 3100 hrs before I cracked mine open and it was still in good condition. The bearing showed some minor wear but the bolts measured out to the replacements, so they didn't have the noted stretch. I do have the Ambac system so it was already slowed down. The 670I crank in the N5 weren't known for trouble, the N6 with the extra 200 rpms had most of the troubles. And here in the Midwest, Cummins seems to be the choice for repower, but the Cummins repower costs equal to 2 good shape 670I complete Overhauls. Unless you open it up and find many problems I would keep the 670I. Dealer looked mine over while in it and figured I would go over 6000 hours before major was needed. I have 2 AC8000 series with the 670 and both went over 5000 before OH and both had nozzles that created the OH. I bought both fresh out of overhaul.

John, Isn't that the same engine as the 3500 found in the tractorsIJ I did the under-haul on mine this summer. The rod bolts aren't "torque-to-yield" but rather "torque-once" they don't stretch but evidently you are not supposed to re-use them, or even use them to check bearing clearance if you put new bearings in. If I remember right they wanted the threads and heads oiled with straight 20W oil and then torqued to 68.5 lbs_ft. We didn't have a 1_2 drive wrench that displayed in half pound increments so we decided to live dangerously and do 69 lbs_ft. Sheeesh!! Ed in Montana

The 670T_I are the 426ci block, but with many updates. The 670HI is the 426 block with the balanced crank of the 7080_7580_early N6 and due to high rpms where known to stretch and break the rod bolts and normally leaving an easy way to put oil in the engine. The 670I is used in the N5_late N6_8050_8070_4W220, due to the Ambac fuel system delivering the same torque and hp at lower rpms, the 670I was far less prone to breaking bolts and throwing rods. There are numerous internal difference between the 3500 and the 670I as well as a few external. lube and cooling are the main differences.

Good satire regarding torque, Ed. Have you guys ever had your torque wrenches re-calibratedIJ I send mine to the factory repair center every 3-4 years or whenever we need to do intricate work like con rods. A 50-dollar bill is a good investment for peace of mind. Tom in MN

Tom, do you usually find that the wrenches are a long ways offIJ The "head wrench" around here has a couple Snap-ons and maybe a Mac or two. To hear him tell it, those things should never be off. Now my hi-quality C.H. Ina stuff should probably be sent in once in a while. Ed in Montana

Ed, I dont have the quality torque wrenches you guys have; mine are the clicker type from Sears that usually have something else wrong with them like the little viewer is cloudy from someone putting an oily finger on it. Another thing that starts going south is inaccurate readings at the bottom end of the scale. The only way I have to check accuracy is to connect 2 torque wrenches with female-to-female adapters, set both to the same torque value, and see if they click at the same time. There hasnt been much variation in the middle of the range, but readings toward the upper or lower end can be off. These F-to-F adapters are Snap-On items that are advertised for tightening square headed setscrews. They are good tools to have when working on combine sheaves and sprockets as well as checking torque wrench accuracy. Okay Ill bite. What is C.H. Ina stuffIJ Tom in MN

What's C.H. Ina stuffIJ You know. Go to the local discount hardware store and look in the bargain tool bin. You should find some tools there that have no brand name. Only those 5 letters "C H I N A" Gotcha !! ;-) Ed in Montana

Yes you did, and you didnt have to work very hard at it!