My first restoration soon begins a Model 70

[Leon renaud]

I'm about to begin tear down of a model 70 which I will post pics of soon.I am interested in learning of any upgrades or improvements that I should consider making while I'm rebuilding things.I have been reading lots of past pages but for some reason I can not access the Archives it just won't let me in so searches are bringing up very little.
One question I have is "Can the 7HP Kohler be bored to take the 10 Hp piston?"I was told by my father in law the dealer did this to his 70 back in the mid 60s that both engines are the same other than bore.I plan on running a loader on this machine and possibly a back hoe.
Thanks in advance
Leon

[eastonct124]

I'm only going off specs, leon....but all the engines jump .250" over the the previous model's bore. That's 1/4". I don't see how any kohler block, can be "made" into another HP engine.
But, I'm no expert on exactly what CAN be done as far as machining modifications with them.
Either way, a 7hp kohler, though it sounds small, has tons of torque, and will out pull an equivalent sized tractor with a new 14hp "other brand"engine.

[Yosemite Sam]

As far as the Kohler 7/8 hp engines that were used on Cub Cadets, they are a completely different engine than the 10 hp and bigger engines, almost as though they are a scaled down version of the larger engines.

[Merk]

7 horsepower Kohlers had a big and small bore cylinder/piston.The motor(s) from a 70 and a 72 that I rebuild were both small bore cylinders. Not sure if the motor in the 72 was the orginal one.
The big bore 7 horsepower motor had a bore of 2.938.
The bore of a 10 horsepower Kohler is 3.251.
That is a difference of .313.
You will take too much out of the cylinder to be safe to run.
The above infomation came from page 1.6 of a Kohler Service Manual. A service manual is a must to do any motor work on your Cub's motor.

I wouldn't use a 70/100 frame with a loader/back hoe set up. The frame isn't strong enough and there isn't enough motor to run the tractor and the hydraulic pump to run the loader/back hoe. I would use a wide frame hydro Cub Cadet with a 12 to 16 horsepower motor.

The 70 that I restored in this topic
http://www.onlycubcadets.net/forum/s...ght=Uncle+Dick
had a small bore motor when the motor was rebuilt. It now has a big bore piston in it. The power the 7 horsepower motor makes is impressive. I had no problems pulling a 10 inch moldboard plow this fall.

[Matt G.]

I restored a 100 (same as 70 with a 10 hp engine) this past summer, and the details of it appear in this thread. You might find some info in there helpful as well.

http://www.onlycubcadets.net/forum/showthread.php?t=879

[transformer]

Hey Leon we too are starting our first project a 70 just getting started a little at a time.I got a little wrenching done on my 70 today working on the steering.Ive learned 2 things since I started. 1 read this forum till your head hurts. 2 always have your service manual at your side when your working on your tractor. Had to learn that the hard way. lol. Two threads that are a must for you are Merks 70 restoration and Matts 100 restoration..They have been a savior for me...Thanks guys....I have to agree with Merk on the fact that the 70/100 would be way light for a loader or a backhoe.Ive been around and on equipment my whole life and from my experience the lighter the machine the more trouble you have from them and the less you can do with them.But thats just my 2 cents.Like you Ive also had trouble with searches looking for specific things here...But these guys here we'll be glad to help ya when you get confuzzed...They sure have me...The steering upgrade with a thrust bearing I think is a must. I ordered my parts for mine tonight after tearing down and cleaning everthing up today..Let me know If I can help maybe help each other...Oh and Merk How do you know what bore you have in a 7 horse didnt know there was big and small bore 7. Can you tell that by the numbers on the engine or by a tear down?

[Merk]

I found out about the difference in bores when I rebuilt a 7 horse motor. The machine shop I used told me. There may be a serial break down....haven't found it.

[eastonct124]

The spec sheet lists the early block as a k161s, and the later as k161s3564d.
Whether it's marked on the block or not, don't know. Measuring the bore is an easy indicator. I can't find any further documentation on it.

[klejeune]

When I rebuilt my CCO K161S I found out it was a small bore too. I had already ordered the .010 over piston and when it came in I found out it was a .010 over the large bore. I had it bored out to fit anyway. I should have got a standard large bore piston. The large bore 7hp is the same bore as the 8hp K181. They get the larger displacement from the length of the rod in the 8hp.

Lesson learned. Measure first and then order the piston and have it bored to fit the piston you have in hand.

[Leon renaud]

Matt and Merc
I been living at your web sites and Also read all of Uncle Daves? Tractor restoratin.As for the loader If you check my past post My Father in laws 70 came with a Danco loader on it and he worked the tail off that thing!I found and am trying to buy back HIS original 70 but the guy just won't give it up yet and it needs complete restoration!been sitting rotting in his yard under a tree for over a year I know of but "I'm going to fix it"I even offered a Wheelhorse 16 hp tractor and a trailer in trade !he will never fix dads up I just gotta catch him at the right time.I can't get into the Archives unless I get a specific link for some reason but I have read most every post on the 38 pages I have been able to get to in the forum.My original Question is what upgrades should I consider as I rebuild I'm sure you guys all have some little tricks you've applied to your rebuild like say Electronic ignition or milling the heads etc.I'm open to anything to improve the tractor as I rebuild.
Thanks Leon