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Patrick Reese

Tecumseh HH60 valves/valve guides

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Patrick Reese

Looking for some advise or help.. I have a recently refreshed HH60, I say refreshed because we did not do a soup to nuts rebuild, which is what brings me hear. It seems that when we took it apart and replaced the piston, rings, rod, lifter, did a valve job and put it back together we did not check the tolerances on the valve guides. On the tecumseh they are heat pressed (I believe) in the block during manufacture and the only thing that can be done with them when they are worn is to find oversized valves and ream out the guides..

 

It seems that after a good break in period that the engine is still burning oil and fouling plugs. It is behaving like it is the valve seals. (reminds me of my old high school '67 Impala with bad valve seals) There is plenty of compression, and it is usually smoking only after idling for a bit and going from low speed to high speed. It is not chugging blue smoke under load. It is however fouling spark plugs terribly.. when we dissassembled the engine upon purchase there was evidence of heavy carbon build up in the valve areas and the lifters were worn in one spot telling me that they were no longer spinning in their bore. I should have picked up on this but not being a small engine mechanic only an occasional hobbyist this got by me.. all these things to me add up to loose valve guides.

 

Now the questions...

 

Does anyone have experience with matching up oversized valves for these small engines? NOS Tecumseh oversized valves are probably as scarce as hen's teeth. I'm wondering if my local automotive machine shop could take some measurements and find an automotive valve that would be the same size or close enough that it could be machined to fit??

 

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sorekiwi

I cant help you specifically, as I havent done too much with tecumsehs, but what you are saying makes sense.

 

I work at a place which rebuilds auto engines from around 1920. and the valves we use on our engines start life as replacements for truck engines.  The head of the valve is reduced in diameter, the stems are shortened and then machined to suit the "keepers" for the valve spring.

 

Years ago there were machine shops that would machine the guides oversize, fit a thin wall bronze bushing, and ream to suit the valve stem.  I don't know if that is still common practice or not.

 

The K series Kohlers have a pressed in valve guide, I wonder if the Tecumseh block could be machined to suit one of those.

 

It may be worth searching on www.smokstak.com - a whole bunch of crazy people resurrecting old engines.

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Patrick Reese

Thanks for the reply sorekiwi, I have an auto machine shop near me that I have used in the past to do machine work on two old Pontiac's I restored. They are great with automotive engines and nice guys to boot. Come Monday I'm going to see what, if anything they might do to help me out with this small engine. Seems to me like rebushing the block would be the easiest interms of leg work.. also the valves in the engine now are recently reground and the seats resurfaced as well as valves ground down for clearance.. rebushing the block should allow me to reuses all the components as-is.

 

sorekiwi as to installing a new pressfit  valve guide I'm not sure how the aluminum block would be with that. I think I read where the stock guides were heat pressed in upon manufacture? Just not sure of all this.

 

Has anyone had any success or experience installing new valve guides or adding bushings?

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sorekiwi

I thought the HH60 was the cast iron version?

 

PICT0003-2.jpg

 

H60 on the left HH60 on the right.

 

Aluminum engines have a steel valve seat shrunk into the block, I'm not sure about the guides on a Tecumseh.  I'll go dig one out of the garage in a bit and have a look at it.

 

Also I am guessing that you don't know if it is the guide itself that is worn or the valve stem (or both).  I have had Kohlers where the valve wiggles badly, but most of the wear was on the valve stem, and the guide wasn't so bad.  Possibly new (standard size) valves may help your issue considerably.

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Patrick Reese

OH I think I mispoke.. I have the HH60 which is a cast iron block and aluminum head.

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Callen

If your lifters wore in one spot, you need to find a different camshaft. The lobes are manufactured with a slight taper to make the lifters turn. If the valvestems are worn, you would see a definate step. The machine shop should be able to counter bore the valve guide and drive in a brass bushing and finish ream to std size. I would check the crankcase vent to make sure it isn't clogged and the reed is working correctly. That will make it force oil past the guides even if it isn't worn.

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sorekiwi

I agree that a machine shop should be able to do something with the guides.

 

It would be worth contacting this guy:  http://shop.ruppparts.com/Bronze-Valve-Guide-Liners-H22-HS50-bronzeguidepr.htm.  This link doesn't specify the HH60 engine, but they may work.  I talked to him a few years ago, and he really knows his Tecumsehs well.  He owned a Wheel Horse as well, if I remember correctly.

 

But do check the valve stems for wear, I have seen quite a few engines that were more worn on the stems than the guides.

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Patrick Reese

Callen, the camshaft looks like new.. there is no visible evidence of wear. Even the mechanic that did the valve job for me commented on how it looked almost new. Don't know why the lifters stopped spinning.

 

sorekiwi as to the valve stems being worn we did mic them before grinding and no wear was evident..

 

Callen, this morning I removed the reed valve assembly. IT looked like it was free, but I did soak it lacquer thinner and found that there was gunk inside the reed valve. One thing I did change.. when I had assembled it the first time I put it together with the filter mesh away from the vent pipe this time I assembled it with the mesh and opening to the reed valve in direct line with the vent pipe. Maybe, and that's just maybe this was obstructing the ventilation enough to push some oil upwards. The breather assembly did have oil puddled up inside the housing when I took it apart.

 

For now it seems like it is smoking a whole lot less (only a tiny bit when going from an extended idle to a full throttle) and every once in a while at idle it will "putt" and puff a tiny bit of smoke. The true test will be if it still fouls plugs. I still think we are going to address the valve guides over the winter though.


PS I just checked an engine diagram that I downloaded and it shows the vent pipe inline with the reed valve opening and mesh so I did in fact have it assembled wrong.

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sorekiwi

That could quite possibly be your problem.  If the crankcase does pressurize it not only can push oil up through the guides, it can also push it up past the rings as well.

 

Tecumsehs are also very sensitive to the oil level.  I don't know how it works, but if you overfill them by an ounce they seem to puke a quart out of the breather.

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Patrick Reese

 

Tecumsehs are also very sensitive to the oil level.  I don't know how it works, but if you overfill them by an ounce they seem to puke a quart out of the breather.

 

Probably has something to do with that "dipper" on the end of the rod slinging oil up at the lifters! The our Tecumseh is also hard to check when the oil is fresh. Almost impossible to see the oil on the dipstick since it takes so long to unscrew it to get it out any decent amount of oil runs off the stick.

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