tecumseh cam shaft bushings

[Dhodge 528]

has anyone successfully machined any hh120 cam shaft bushings? I am rebuilding a very worn hh120 and my cam shaft was worn and out of round on both ends of the cam shaft, so I turned them down a few thousandths to clean them up. amazingly the cam lobes were not worn and the gears are in great shape. I am working on getting the bronze bushings out of the block so I

can make new ones sizes to fit the newly shaped cam to be pressed back into place.

Has anyone else experimented in this area that can chime in with their experience?

I found that the lobes on the cam were slightly larger than the allotted tolerances in the service manual for an hh120.

After further review I found that my hh120 must have had an oh120 cam shaft inside it. According to the service manual the

oh120 had slightly larger cam lobes, but otherwise the same. Kind of amazing what you run across and what people do to keep these things running. Just my assumption. I cannot figure any other way the cam lobes would be larger than specifications.

I may be deeper into this rebuild than I should be, but I want to keep my C-120 tecky powered auto original.

[Dhodge 528]

I must be in my own little world over here!!!!

[slammer302 2,156]

When it comes to Tecumseh there just not a lot of excitement but there is a small fan club here more in the smaller teckys though I just put an h60 back together last night runs great

[tbarnhart 240]

I don't  see any reason why your approach shouldn't work. When I redid my OH160, I didn't have to mess with the cam bearings. I have heard that the OHV cams were a performance upgrade the the HH engines because of higher lift, but I've never been able to prove it. As you said, the specs do show a different profile, but I don't what the differences are in lift, duration, or timing. Check the little pin that activates the compression release. Those will wear and not open the valve when the valves are set to proper clearance. Its especially critical on the OHV engines with higher compression. The starter hates that. The cheap fix is to set the valve clearances tighter, but that only works to a point. The time to fix it is when it's apart. Also curious what your cylinder looked like. Mine only needed a light honing and went back with the original piston and new rings. I don't know how many hours were on it but I know it was a lot from the other wear points on the tractor. I've heard that the Tecky cast blocks were an excellent grade of iron that resisted wear better than (dare I say it) the Kohlers. There might be a reason why Tecky oversize parts are harder to find. You just cant wear them out. You do want to keep that tractor original. The only model of c-series with a Tecky and an auto. My 160 is a '74 model as well.

[wheel-mule 46]

I would use oil lite bronze bushing material for the bushings.Make the bushing OD .001 -.0015 larger than the hole in the block so it has to be pressed in.Keep in mind this will compress the ID when installed,so you will need to make the ID of the bushing at least .002-.003 larger than the new cam dia,so after install the cam will still fit plus have .001 plus clerance to turn.I'm one the the people that LIKE Tecumseh engines.

[Dhodge 528]

Thanks for the input fella's. It was a bit of meddling getting the old brass bushing out. I used a die grinder and a small chisel, but they are out. I have started machining my inside diameter of the new bushing. I am in fact oversizing it .003 larger than the cam shaft ends I machined

yesterday. I plan on machining the outside diameter .001 larger than the castings in the blocks so hopefully I have

estimated correctly.

My cylinder was out of tolerance, so I am boring it 0.20" over size. My crank journal was 0.80" out. I ordered a standard

rod and a .10" under

sized rod that I found on Evilbay. I have another useable crank, however I may have the crank journal wire welded up and

turned down to standard size or I will turn the back up crank down to .010" under, not sure at this point. I cannot believe this engine was still running and cutting grass, but it was.

I have mostly Koehler's and I like them a lot, however the cast iron Tecky's are pretty dang good engines too. I like them

both very well.

This is my first time doing the repairs I am working on currently and it is a fun little learning experience so far.

Cam shaft bushing making 101 - he, he

Edited December 28, 2014 by Dhodge

[slammer302 2,156]

I look at the Tecumsehs as a new challenge and something different to work on besides kohlers

[Dhodge 528]

Old bronze cam bushings are out, new ones were cut inside diameter to fit the cam shaft I turned down to clean up for fit. I turned

the outside about .001" over size pressed them into place. They actually press down and fit onto a shoulder about 1/8" above the

bottom of the port hole in the block castings. The casting has a groove, on one edge leading to the bronze bushing, so I had to mill a notch on the top of the bushing once in place. Then I ground a small groove down the inside length of the bushing to allow oil to

pass down between the bushing and cam shaft end. It will also allow oil to get down between and rest in the 1/8" area between the cam shaft end and the block casting on both halves. The finished work looks as it should and I am quite happy with how everything fit

and how it looks. Now I am waiting on the .020" oversized piston and the .010 undersized rod to arrive so I can have my machine work completed and ready for reassembly. I have a new gasket set coming as well, so I will be re cutting the valve seats and grinding the

valves while I wait. New crank shaft bearings and seal will be ready as well.

I know this is a lot to go through when I could have bolted a Kohler on, but I have lots of Kohler tractors, plus I wanted to keep

this old 1974 C-120 Auto original and that cant be done by bolting a Kohler up to it. I believe 1974 was the only year they put a

Tecumseh on a C-120 auto.

[Dhodge 528]

I guess I should put something in my avatar so I don't have to be a snow flake any more!!!!!

Geno---can you help with that??????