# Can you adjust valve clearance without removing head/valve



## hatrick (Feb 22, 2019)

Finally took my ‘79 Ariens with an 8hp HM80 to the shop as I just couldn’t get it to run good after rebuilding 2 carbs and checking a number of other things. They said it had low compression due to a worn exhaust valve and wanted over $400 to do a valve job. I figured I’d give it a try and see if I can get it fixed and was wondering if I should just start by adjusting the valve clearance and if I could do that without taking the head off and valve out? I’m guessing that the clearance is to longer there and the exhaust valve isn’t fully closing. It ran fine last year and earlier this year so I’m hoping it isn’t really that bad and a valve twea is all it needs.


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## 4getgto (Jul 20, 2020)

You won't have to take the head off (to check) the valves for clearance but you will if they need adjustments. Valves have to be pulled out and stems ground to make adjustments.
And till you do all that you might as give it a full valve job.

I'm not sure where that shop is getting $400 to it though.??????? Blower probably ain't worth that much.


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## crazzywolfie (Jun 2, 2014)

how mechanically inclined are you? i usually avoid pulling the head unless i have to but i guess to fully do the job properly i can understand why you should. without pulling the head you don't know if the valve need to be lapped or not which you do have to remove the head to see. you do usually need some specialty tool. i usually use a valve spring compressor to lift the valve up, file some material off the valve and then let it back down over and over till it is within spec.still $400 seems like a bit much. i think the shop just didn't want to take on the job which is why they threw such a high number on the job.


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## paulm12 (May 22, 2015)

did they say worn valve or worn valve guides? Valves are easy to replace, valve guides may not even be replaceable. though they may have a manual process for that.

tx


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## hatrick (Feb 22, 2019)

I think they said valve seats and that the valves would need to be lapped. I agree that I don’t really think they wanted to do the work. They said it wasn’t worth the cost and I should just but a new machine.

I love these old Ariens machines so I’m not ready to give up. I guess I may as well give it a whirl on doing the valves myself. Is it worth the extra $30 to just get new valves versus cleaning the old ones? Lapping tools and spring compressing tool is only $35 so I can probably do everything for well under $100.


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## hatrick (Feb 22, 2019)

Too bad I couldn’t just file a bit off the valve stem through the breather cover access and not have to take the head off just to see if it helps. I guess that would be tough and potentially leave filings.


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## crazzywolfie (Jun 2, 2014)

hatrick said:


> Too bad I couldn’t just file a bit off the valve stem through the breather cover access and not have to take the head off just to see if it helps. I guess that would be tough and potentially leave filings.


you can or at least that is how i have done it. you just have to be careful. the machine i did it to is on winter number 2 and still going. it doesn't get used all the time since i am the only 1 using it but it does usually start with 1 pull and seems to run good since. you use to be able to muffler on it glow during the day with how bad the exhaust valve lash was on it.

also you are probably good just using your old valves unless they are damaged or wore out.


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## hatrick (Feb 22, 2019)

That’s great that you were able to adjust your valves without taking everything apart. Any tips you can give would be greatly appreciated. I was thinking of getting one of these spring compressors unless you have a better recommendation.


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## crazzywolfie (Jun 2, 2014)

i got 1 more like this. the one you posted a pic of looks like it would make the job trickier 








8" Valve Spring Compressor Hand Tool Automotive Engine Compress / Release New : Amazon.ca: Automotive


8" Valve Spring Compressor Hand Tool Automotive Engine Compress / Release New : Amazon.ca: Automotive



www.amazon.ca


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## hatrick (Feb 22, 2019)

Thanks for the tool advise. I can see how your tool would make it easier to adjust the clearance when not removing the head. By compressing the spring upward it would give better access to the tip of the valve stem and give enough room to get a small file underneath in that tight breather housing. With your tool it actually looks pretty easy. Thanks.


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## nwcove (Mar 2, 2015)

Why not just repower with a clone ?


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## tadawson (Jan 3, 2018)

Some prefer to not downgrade, esp. when maintenance on what you have is quick, easy, and zero cost, perhaps?


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## crazzywolfie (Jun 2, 2014)

tadawson said:


> Some prefer to not downgrade, esp. when maintenance on what you have is quick, easy, and zero cost, perhaps?


i really don't see how a clone engine is a down grade. i personally usually look at it as an upgrade but if you want to be cheap and it is as simple as filing a bit of material off the valve to keep the machine going for a little longer then that is ok to if that is all that is wrong with the machine.


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## nwcove (Mar 2, 2015)

tadawson said:


> Some prefer to not downgrade, esp. when maintenance on what you have is quick, easy, and zero cost, perhaps?


Jmo, but a clone is not a downgrade from a tired flathead tech. More power, easier starts, quieter and for $99 bucks down there....its a no brainer unless the op likes to tinker and doesnt need the machine ......again jmo.


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## crazzywolfie (Jun 2, 2014)

nwcove said:


> its a no brainer unless the op likes to tinker and doesnt need the machine


you could say the same about a clone swap. there is no guarantee that a clone swap would be any more or less reliable than a old Tecumseh engine. most of the time it comes down to stuff like maintenance. because of epa standards clones have really tight carb tolerances which can cause them to be less reliable. the only real advantage better fuel economy and maybe a bit quieter depend on the machine and the muffler it has on it. the one used on good snowblowers tend to be larger which results in them being quieter than what you find on most clones.


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## hatrick (Feb 22, 2019)

I really love these older machines and want to keep it original. I have 3 ‘79 machines so learning to do a valve job it probably a good thing. I like to tinker and learn more about these. I gave up on classic cars so maybe restoring an older machine is in my future.


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## 3vanman (Nov 21, 2017)

hatrick said:


> I really love these older machines and want to keep it original. I have 3 ‘79 machines so learning to do a valve job it probably a good thing. I like to tinker and learn more about these. I gave up on classic cars so maybe restoring an older machine is in my future.


If you don't mind bending (or sitting) you can actually do most of the job without removing the engine, or belts.
First time will take a bit longer, but by your third machine, you'll be a pro.
Minimal tools needed, and I recommend lapping the valves while you are at it.
Head gasket and breather gasket, plus maybe an intake manifold gasket are all the parts you need.
There is a lot of info on You tube explaining how to do this job.
Donyboy73 has a huge library of snow blower and small engine repair.


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## tadawson (Jan 3, 2018)

nwcove said:


> Jmo, but a clone is not a downgrade from a tired flathead tech. More power, easier starts, quieter and for $99 bucks down there....its a no brainer unless the op likes to tinker and doesnt need the machine ......again jmo.


Hmmm . . .Tec goes 42 years, that's hardly a problem. Offshore junk hasn't even existed that long . . . When they get to a similar age, still have parts, and are still running, then _maybe_ you can say that. For now, all we have is the questionab,e QC and materials of the el-cheapo clones . . . vs proven longevity of the old Tecs. It went 42 years the first time - refresh it and it's realistic to expect a similar life span the second time around!


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## drmerdp (Feb 9, 2014)

I’ve revived a number of tired tecumsehs by filing the stem through the valve cover. Fast and dirty but does the trick. Some machines just aren’t worth fixing correctly. If you have a twin shaft tecumseh your options are limited. But as for single shaft engines... I love a good engine swap with a Honda or Clone.


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## ST1100A (Feb 7, 2015)

drmerdp said:


> I’ve revived a number of tired tecumsehs by filing the stem through the valve cover. Fast and dirty but does the trick. Some machines just aren’t worth fixing correctly. If you have a twin shaft tecumseh your options are limited. But as for single shaft engines... I love a good engine swap with a Honda or Clone.


Some of the old 'Small Engine Repair' textbooks used to show you how to do that. File the valve stems while they were in the engine instead of taking the valve out.
You would lift the valve up off of its lifter and the spring tension would give it the pressure against the file. It worked, just took some time.


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## ST1100A (Feb 7, 2015)

hatrick said:


> I really love these older machines and want to keep it original. I have 3 ‘79 machines so learning to do a valve job it probably a good thing. I like to tinker and learn more about these. I gave up on classic cars so maybe restoring an older machine is in my future.


It becomes an 'Addiction' after a while, and it is not as expensive as a classic car but just as fun and satisfying.


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## hatrick (Feb 22, 2019)

I ordered a spring compressor and I’ll try just filing the tip of the valve stem to get the clearance back to spec just to get through thus season. Then over the summer I’ll go for lapping then valves. I still have to get a new breather gasket... should I also get a new breather while I’m at it?

I was also thinking of pouring a bit of Seafoam down through the spark plug with the piston at top dead center and let that sit for a day or so to try to loosen some of the crud up. Any value in that theory?

I’m actually kind of looking forward to this job. Hope this makes a big difference.

Unlike classic cars, these are way cheaper and now I have room in my garage for my Jeep.


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## hatrick (Feb 22, 2019)

Just as a double check... does anyone have the valve clearance spec for a ‘79 Tecumseh 8hp 155128c? From what I could find online, .01 seems like a good target for both valves.


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## Preacherman (Dec 20, 2020)

hatrick said:


> Just as a double check... does anyone have the valve clearance spec for a ‘79 Tecumseh 8hp 155128c? From what I could find online, .01 seems like a good target for both valves.


.010 is center of specs .008- .012!




https://www.barrettsmallengine.com/manual/tecumsehlheadmanual.pdf


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## ChrisJ (Nov 27, 2014)

If memory serves, on my 1998 HSMK80 I aimed for .008 on the intake and .012 on the exhaust. The reason was mine were too tight and the exhaust valve wasn't closing fully after running a while under load. I believe the range for both was .008 - .012 but I felt having the exhaust on the larger side was better.

I didn't need a spring compressor, just two screw drivers.


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## drmerdp (Feb 9, 2014)

ST1100A said:


> Some of the old 'Small Engine Repair' textbooks used to show you how to do that. File the valve stems while they were in the engine instead of taking the valve out.
> You would lift the valve up off of its lifter and the spring tension would give it the pressure against the file. It worked, just took some time.


Its definitely tedious, I have a nice long file that I clamp a vice grip to the end for more control. I only use the last inch of the file because of the space constraints. Once I’m done I break off the used inch and have a fresh section of file for the next one.


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## Jatoxico (Jan 6, 2018)

Took a few thousanths off the exhaust valve on my HM80 without removing the valve. With valve tappet down (spring extended) I strung a zip tie through a few coils. raised the valve (compressed sping) to max height and tightened zip tie. Then spun motor again to drop tappet away from the valve. Used a carpenter's pencil to level off the keeper and files away.


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## hatrick (Feb 22, 2019)

Very cool trick!! I wish I had know that one before spending $25 on a valve compressor. How did it work out for you... any noticeable improvement in how your engine ran?? I'm hoping to work on mine tomorrow when I have some free time.

Also, did you do anything special to get rid of the filings or just shop vac it out and give it a good wipe after you were done?

Love this forum and all the knowledge and help!!!


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## Jatoxico (Jan 6, 2018)

hatrick said:


> How did it work out for you... any noticeable improvement in how your engine ran?? I'm hoping to work on mine tomorrow when I have some free time.
> 
> Also, did you do anything special to get rid of the filings or just shop vac it out and give it a good wipe after you were done?


Well I just did it today and the problem/concern I'm trying to address is that the exhaust valve was _just barely_ in spec cold (0.008 was little tight to my feel) and after running under full load for awhile it began to run rattier and rattier as it got fully hot. More popping, more muffler flashes and backfiring than earlier in use so this was my diagnosis and fix. After it cooled it was better behaved. I also noticed the other night, that the part of the muffler normally covered by the heat shroud was dull red. IDK if thats normal since its usually covered and ofter daytime but seemed like more evidence of an exhaust valve not fully seating.

After filing I ran it for 20 minutes or more 2X while I readjusted the carb, set the rpms and futzed around and it does seem better. Its smoother than it was before w/o load where before it tended to hunt and pop more with the occassional flash from the muffler (it was always much better at least early on while tossing snow). But the real proof will be under true operation for an hour or more and the dreaded EOD.

As far as filings I kept putting grease over the tappet to catch any filings and wiped it down each time I checked the clearance. I also covered the oil return hole with paper towel. Most of the filings seemed to end up on the file itself. I feel good about it and it didn't blow up yet.


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## hatrick (Feb 22, 2019)

Oh my goodness what a difference .012 makes! Finally got some time and sure enough my exhaust valve had zero clearance. The intake seemed fine at .008 so after a bit of filing I got the exhaust valve back to .012. Got things back together and with barely half a pull and she roared back to life. Normally it was a bit of a fight with 5-6 pulls and playing with the choke to have any chance of getting started or giving up and using the electric starter. After a quick carb adjustment I now have a nice low idle and smooth high end with pretty much no popping or surging if any at all. I’m sure more time fine tuning the carb will get it even nicer.

The only thing that could possibly be better would be a bit more responsiveness to the throttle control. Seems to be some lag when lowering and raising speed in the low and mid settings but ramps up nicely when I open it to full. Just seems to take a few seconds to change engine speeds but does finally get there. Not sure if that is further adjustment of the throttle cable where it clamps down or if it is just inevitable on a machine with more hours and wear. I do notice the governor is a bit sloppy where it sits in the housing (it can lift up and down a bit and isn’t really tight) but it seems to function properly. But that seemed to be confirmed as somewhat normal in another thread I posted a few weeks ago.

The last thing I need to do is recheck my compression. Before I adjusted the exhaust valve I was only getting 15lb with a cold engine using the hand pull. I'm sure that is way better now.

This has been a game changer in the learning department. Especially owning three ‘79 machines (two 8hp and one 7hp). I’m glad I didn’t listen to the shop and give up on this machine. Basically this is my workhorse. Thanks to all for the help, advise, tips and most importantly the confidence to fix this one.


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## Toro-8-2-4 (Dec 28, 2013)

Keep in mind you have compression release on the exhaust and you will not get an accurate compression reading when by pulling by hand.

You may want to check the governor adjustment. Donyboy73 has a good instructional video on doing that on a tecumseh. Good Luck.


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## Jatoxico (Jan 6, 2018)

hatrick said:


> I now have a nice low idle and smooth high end with pretty much no popping or surging if any at all. I’m sure more time fine tuning the carb will get it even nicer.
> 
> The only thing that could possibly be better would be a bit more responsiveness to the throttle control. Seems to be some lag when lowering and raising speed in the low and mid settings


Very similar performance. It stutters a bit going from idle full speed but runs well at upper ends of the throttle. I cannot stall the engine when idling with the low speed adjustment screw. Not sure if that's normal but doesn't seem right.


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## hatrick (Feb 22, 2019)

The compression release will definitely keep me from getting a true reading but I’m more looking for the relative improvement. Hoping for something in the 40-50 range from seeing others doing a similar cold hand pull start test (and a Donyboy73 video doing this test).

I’m pretty sure my governor is adjusted ok and functioning properly since I’m running about 3400-3500 rpm and it seems fine under load. Ran it full on into a 20” deep snow bank and it didn’t bat an eye going in over 4’. The governor just seems a bit worn and loose where the shaft comes out of the engine housing versus my low miles 8hp where it is nice and tight and solid.









1979 8hp - Possible Governor Issue - Idling Problem


So I have a 1979 Ariens with a Tecumseh 8HP engine (155128C) and I’m wondering if I have a governor issue. The motor just won’t idle smoothly and consistently but will run at full throttle. I rebuilt the carb and tried a cheap aftermarket carb with the same result. I’m wondering if the governor...




www.snowblowerforum.com





Overall I’m thrilled and can’t wait to give her a try next storm.

Jatoxico... not sure on your low idle screw adjustment but mine seems to be able to stall if I go too low on that screw and the engine really races if I go to far in.


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## Seaweed (Jan 18, 2016)

Trayl has a good video on this too. 



The info starts at 5:27.


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## Seaweed (Jan 18, 2016)

Hi- I'm not sure I'm posting this right but here goes. I want to do this on my HMSK100, having the same issues as hatrick and I have a couple questions also don't want to take the head off right now.
1. How do I insure I'm at the TDC to take my initial gap measurement and subsequent measurement after filing?
2. Did you replace the gaskets? And do they go on dry? With some oil?
May have some more but that's it for now. 

Thanks, Rich



Jatoxico said:


> Took a few thousanths off the exhaust valve on my HM80 without removing the valve. With valve tappet down (spring extended) I strung a zip tie through a few coils. raised the valve (compressed sping) to max height and tightened zip tie. Then spun motor again to drop tappet away from the valve. Used a carpenter's pencil to level off the keeper and files away.
> 
> 
> View attachment 175636


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## Jatoxico (Jan 6, 2018)

Seaweed said:


> Hi- I'm not sure I'm posting this right but here goes. I want to do this on my HMSK100, having the same issues as hatrick and I have a couple questions also don't want to take the head off right now.
> 1. How do I insure I'm at the TDC to take my initial gap measurement and subsequent measurement after filing?
> 2. Did you replace the gaskets? And do they go on dry? With some oil?
> May have some more but that's it for now.
> ...


I did not have to replace any gaskets. I had the head off before and it is not torqued down very tight. The gasket came off easily and I felt it could be used once more. Same with the breather gaskets and the carb (which was new). All gaskets went on dry w/o any sealer etc.

As far as TDC, I determined my initial valve lash when I had the head off. I wanted to see if the valves were loose. The lash on the exhaust was barely in spec but neither was so loose that I could spin by hand. After decarboning and buttoning everything back up there was no improvement in how it ran (still too many pops and muffler flashes) and as I said in my case it would run even worse after fully hot.

So when it came time to grind the valve I just watched the valves and figured out which stoke I was on and carefully watched the lifters/tappets for movement to get to TDC. Then I removed about 0.004 so 0.012 is just tight by my feel. It is running better overall and did get one full workout which suggested improvement.


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## Toro-8-2-4 (Dec 28, 2013)

Seaweed said:


> Hi- I'm not sure I'm posting this right but here goes. I want to do this on my HMSK100, having the same issues as hatrick and I have a couple questions also don't want to take the head off right now.
> 1. How do I insure I'm at the TDC to take my initial gap measurement and subsequent measurement after filing?
> 2. Did you replace the gaskets? And do they go on dry? With some oil?
> May have some more but that's it for now.
> ...


If you remove the spark plug and stick a long thin screw driver in the hole you can feel for the piston to come to TDC. Becareful and move the crankshaft slowly so you do not damage anything. You can certainly do it the way Jatoxico did it but this way gives you a sanity cross check. As long as the gaskets come off clean you can re use. There are benefits to removeing the head. You can fully inspect the condion of the pistion top and cylinder wall. You can also clean and inspect the valve seats. Not to mention a full decarb of the top end of the engine.


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## hatrick (Feb 22, 2019)

I was able to determine tdc by just looking in the spark plug hole with a good flashlight. You can easily see when the top of the piston tops out. Just pull super slowly on the starter cord. May take a few rotations but super easy. As for gaskets... I ordered new ones and a new breather but they hadn’t come in yet so I reused my old ones with no problem and the outer breather gasket on mine tore a tad on the top edge. I’ve had no leakage or issues since it doesn’t seem to be a pressurized system. I did wrap a piece or cardboard with duct tape and put underneath the valve stem before grinding to catch filings and wiped things out after each filing to ensure it was clean. From start to finish it was maybe a 90 minute job. Super easy. Don’t sweat it too much... totally worth it. I’ll likely lap the valves next time around but it seems great for now.


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## hatrick (Feb 22, 2019)

Here’s the tool I got which worked great.





Amazon.com: ABN 8in Valve Spring Compressor, 3-6.5in Capacity, 6in Clearance – Small Overhead OVH Engine Repair Compressing Tool: Automotive


Buy ABN 8in Valve Spring Compressor, 3-6.5in Capacity, 6in Clearance – Small Overhead OVH Engine Repair Compressing Tool: Compressors - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



www.amazon.com


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## Seaweed (Jan 18, 2016)

Hi- Thanks everyone. I wanted to try the easy route first and then take the head off down the road. I do have the same symptoms as hatrick and this seems like an easy fix to get thru the season. Thanks for all the tips!


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