H35 Valve Lash Question

A

AdamE

Well-Known Member
Folks, I'm getting ready to tune up an old Troy-Bilt Junior tiller and had a question about valve lash.

It's got an H35-45593S engine an I found specs that say clearance should be 0.004 - 0.008. Does that sound correct? It's seems like a big range.

Do you like to go right in the middle, or on the lower or upper side of the spec?

Thanks!
 
Yes per the SM that is correct.

Since L head wear and closes the gap over time I would use the .008" spec as the target clearance. It is right the opposite for an OHV engine where the gap opens up over time.
 
Thanks StarTech.

From what I'm seeing though, is that you can't really adjust the valves. You can check them, and if too tight, you can grind them, but that's about it.

This is the first time I've thought about the valves on this small of an engine. I just adjusted the valves on a Vanguard, so I got overconfident.
 
Can only open up the clearances which requires careful grinding the valve stems squarely and sneak up on the desired clearance just like you do a Briggs L head engine. You do have to remove the valves to do this. If you over do it then it is new valves.
 
StarTech said:
If you over do it then it is new valves.
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OR do some lapping which you should be doing anyway if you are that deep into the engine. That can/will alter the gap a touch.

As StarTech was saying, go easy on the grinding. Too much off and you are screwed.

What I do is use some 320 grit wet/dry paper on the valve stem. Nice slooooooo material removal. Checking fairly often after say 5-8 seconds of swiping on the paper. Do NOT get in a hurry. Creap up on the proper clearance gap.

Recommend NOT using any form of grinder or power tool. You will grind off too much. Ask me how I know. Nice gentle sanding and watch the paper as it removes material.

Lap valves first then adjust or sand for your gap.
 
Valve adjustment trick on L-headed Briggs.

Put two zip ties on the spring once you are done gaping for clearance. Insert the now shorter spring into the block. Put the valve spring retainer on and cut the zips off. Easy right?

Remember L-heads need adjustments too.
 
I use a marks a lot pen on the valve stem and a flat file. Each time the color goes away when hand filing the stem will be .001 less. You will be surprised at how fast a good file will remove valve stem metal or even just using 220-320 grit sandpaper on a piece of flat metal or glass.
If that H35 has the adjustable timing on the magneto mounting, pay attention the the correct timing specs in the service manual. It is a critical setting or the BTDC. If set to far advanced BTDC it will eventually lose a rod. (severe kickback when trying to start also) Also there is two different timing specs due to the year of manu per the engine code for the H35 ENGINE in the service manual. If you set the timing WRONG it will not run good. (free Tecumseh L-head service manual download on-line)


Do not use a grinder on the valve stems. You will most likely end up removing too much and then need obsolete replacement valve.
 
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Thanks all. This is getting deeper than I considered.

It would be a cool, learning project to pull the head and mess with the valves. It's something I've never tried.

Actually, the valves may be the problem since after several minutes of use, it starts running badly. It's been so long since I've used the tiller, I forget what is does though.😁
 
AdamE said:
Thanks all. This is getting deeper than I considered.

It would be a cool, learning project to pull the head and mess with the valves. It's something I've never tried.

Actually, the valves may be the problem since after several minutes of use, it starts running badly. It's been so long since I've used the tiller, I forget what is does though.😁
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You wrote:
It would be a cool, learning project

Just a hint. The H-35 is not a cool learning project. If you want a learning project best to go with a Briggs 5 hp area engine. Why, because the Tecumseh H-35 is obsolete and parts hard to find. It;s a good engine BUT really requires lots more attention to detailed tuning as compared to the Briggs. At least download the free service manual before going deep into a Tecumseh and review availability of parts, such as valves, carbs, gaskets, how to set timing.
Also for tiller engines I keep a eye and ear open for replacement engines from power washers that have bad pumps on the cheap. ($50 area) I find really good late model Briggs and Honda power washers engines that fit onto tillers.
 
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