Tecumseh Valve Guide Clearance

[bill18163]

I'm working on a Tecumseh HMSK80 engine. I've got the head off and I cleaned off all the carbon. I plan on lapping the valves and probably replace the springs. I have the valves out and I was going to check the clearance gap when I noticed that the exhaust valve was a little sloppy in the guide. You can wiggle it a little side ways. My question is will this hurt anything? Can I use it that way?

[Arkie]

Just speaking from Tecumseh experience and I eventually come around to where I actually kinda got to like Tecumseh engines. I own several but I'm not married to them.
BUT:

Tecumseh engines are obsolete, parts when found are expensive, and not really worth much effort, time, money restoring a Tecumseh, especially for someone else.

I would do the valve lap and put it together as is for my own use ONLY. If it runs good, Ok, if not throw it back into a weatherproof pile as a parts donor. I would not even replace the valve springs unless I knew for sure they were weak and l-head valve spring usually don't go weak unless maybe for some reason they were subjected to high external heat.

Most likely just a small amount of wiggle test on the Ex valve will be ok, but a wiggle on the intake usually results in oil consumption and carbon build-up on piston/spark plug, but sometimes if it's not worn rings the engine will remain useful for intermittent use, like a wood splitter, Air compressor or garden tiller.

Lots of guys with the old NLA Tecumsehs just replace them with a HF $99 predator engine.
I don't because I do not like China stuff, but I have access to lots of old Briggs and Honda engines.
When scrapping Tecumseh's you need to save the carbs, they are desirable, sell good on flea bay and some of the Tecum carb's will actually bolt onto the Horizontal Briggs engines (some of the 10 year old area Horizontal shaft 5-8 HP Briggs carbs are NLA and no China clones yet) and operate with no mod's at all, even the governor linkages fit.

You can download a FREE Tecumseh L-head service manual for from this site or on-line

[bgsengine]

I'm working on a Tecumseh HMSK80 engine. I've got the head off and I cleaned off all the carbon. I plan on lapping the valves and probably replace the springs. I have the valves out and I was going to check the clearance gap when I noticed that the exhaust valve was a little sloppy in the guide. You can wiggle it a little side ways. My question is will this hurt anything? Can I use it that way?

NAw it's fine I'd say .. most L-heads are gonna be like that anyhow.. once springs are in place, natural action of the valve should center it on the seat.. it'd only start to become a problem when valve faces start getting grooves worn into them on the contact surfaces.. then the slop can make them more likely to hang up and not seat.. after getting myself one of the official briggs valve guide wear check tools, I quickly came to realize that what *I* considered excessive slop was well within Briggs tolerance limits.. so if you call it "a little wiggle" I wouldn't worry much (Besides, considering Tecumseh parts are few and far between and Briggs L-Head parts including valve guides will fast become obsolete now that they're in bankruptcy, your only choices would be to run it til it drops or trash it.. unless you got a machine shop in your back pocket to fabricate parts..)

[KE4AVB]

Personally those Briggs GO/NO GO gauges are a joke. I had to replace valve guides to would pass those test gauges but the engines either wouldn't run or smoked heavily. On those L-heads that didn't either have brass or slithered bronze guides, I had problems getting the replacement guides for use with the Briggs 1/4" valve guide tool kit. At first it was the aftermarket guides that would not fit due to being thicker. I finally got a size larger reamer to take care of that problem. I still had problems with the Briggs replacement guides as they are so thin. Finally I just brought some rigid brass tubes and just use it now. Now the slithered bronze bushings will still need to replaced with the OEM bushings.

To me a little wiggle is subjective as what I call normal and excessive is two different things.

Mentioning Briggs problems I just got a drop shipment of parts or I should I say was suppose to get parts. When I received the package all that was there was a box, plastic air bags and a packing list, but no parts. Parts weren't lost in shipment either as the box was well sealed. Yet I still got billed for the parts. At least it wasn't parts I was needing right a way as they were for stock and I have requested replacement parts.

I also was needing a 330000 series head the other day and was informed they are on back order for at least two months. Lucked out as the valve seat wasn't cracked, just dislodged so my personal mower is back online.

[bill18163]

Thanks guys,
I'll check the lash and adjust if necessary and then lap the valves and put it back together. I'm just curious, are those valve guides a press fit? Are they hard to replace? Again, I'm just curious, I probably couldn't find the parts anyway.

[KE4AVB]

According to the Tecumseh service manual the guides were permanently made as part of the engine. At one time we could get valves with oversized valve stems (1/32" larger) but they are NLA now. The procedure was to ream to the oversize and install the new OS valves.

Now I haven't done this but it should be fairly easy to resize and install a new brass bushing so a standard valve can be used. The reason I haven't try this is that I just don't see Tecumseh engines any more here. Most have died off now. IF the specs I have here for the HMSK80 it would the same as the Briggs 5/16 replacement guides which means you ream out to 11/32, install the bushing, and then finish ream to 5/16. Its just that Tecumseh skipped the bushing installation and opted for an oversized valve stem instead.

Otherwords this means there is more than one way to skin a cat.

[RoyM]

The valve in an aircooled engine has to be a bit loose in the guide to allow for expansion, if it is at automotive tolerances it will seize as soon as the engine gets hot. I learned that the hard way.

[Arkie]

When adjusting the lash, do not take the valve stem to a grinder because you can easily take off too much, just clean the end of the stem good and take a marks a lot pen and color the end of the stem.
Hand file and the color will ID witness you are filing flat and each time you take off the color you have removed .001-.002. off the end. Them stems cut easily with a good hand file.
You can make a dry fit into the engine to get an idea of how much you removed if you will check such before you start by pressing down on the valve head without the spring in place.
Make your first lash test with the springs installed so as too see how much needs removed, then take the springs off and do a dry non-spring test of the lash and using this method you can file adjust the lash without having to install springs each time for a test fit.

It's common for the L-heads lash to close up or get less as the engine wears due to wear of Cam, lifter, Valve face,
so .002 or so over max specs is ok.
With spring installed the clearance is usually about .002 less that a dry non-spring lash.
Briggs L-head manuals lists spec's for springs on and springs off when reading valve lash.

Them Tecumseh valves are hard to find and expensive when found, similar to hen's teeth and dinosaur eggs .