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Old 02-20-2012, 04:40 PM
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Default Tecumseh L-Head Governor Removal

Here's a quick little how-to on removing the governor mechanism from a Tecumseh L-head engine. Shown is an H40, which is identical to many others including the H60 I did yesterday. You will notice the PTO shaft has been hacked off. The 5/8" clutch was perma-frozen to the shaft, and the engine is destined for the scrap bin. Right after shooting these pics I stripped the rest of the guts out and trashed it. Saveable parts were used to repair my H60. I didn't shoot many pics when I did the governor removal to my H60, so I decided to use this engine for a how-to before I scrapped it.

Start with the usual- drain off the engine oil into a suitable container and remove the clutch, pulley, CVT or anything else installed on the PTO shaft. Disconnect the springs and linkages between the governor arm and carb. Remove and discard the arm assembly coming off the governor shaft (seen in top right of first pic). This will just leave the shaft stub sticking out of the engine.
http://www.diygokarts.com/vb/attachm...1&d=1329775346

Next, remove all 8 engine side cover bolts. Laying the engine on the recoil is the best bet here. There's still going to be some oil in the 'case, and (this is one thing I really like about these engines) the entire governor assembly is mounted to the side cover. Once you have removed the cover, you can set the engine aside and not have to touch it again until reinstallation. Gently work the cover loose with a soft-faced mallet, and begin to pull straight off. Cocking the cover sideways may cause it to jam. Do not just start shoving screwdrivers in there to pry it off either. You do not want to damage anything. http://www.diygokarts.com/vb/attachm...1&d=1329775708 Here's a shot of the inside of the side cover. At the top you can see where the shaft enters the engine. You can also see the nylon governor gear, and the retainer/oil deflector plate. (more on that later). Go ahead and remove that plate.http://www.diygokarts.com/vb/attachm...1&d=1329775854 Great. Grab the nylon gear with your fingers and pull straight off. Now, you encounter the spool, which is retained with a spring clip. You can remove this clip with needlenose pliers, a flathead screwdriver, or whatever you like, and pull the spool and washers off. http://www.diygokarts.com/vb/attachm...1&d=1329776071 This leaves you with the shaft and arm assembly. Point it up like in the pic. From outside the case, tap it into the case with a hammer. There is a tiny C-clip there, but it's so much easier to just tap it. It'll pop off. Remove arm from inside the case. Now, all that's left is the governor gear shaft. You can leave this if you like, I opted to remove it. Partially because I make my own gaskets and removing it makes it easy to lay the cover down flat on a sheet of gasket material and trace it out. Should you choose to remove it, here's what you need to know. It's a steel shaft, press fit into the aluminum cover. Grasp the shaft with vise grips and go get your torch. Heat the boss with the torch for about 10 seconds, and twist out the shaft. DO NOT rock or wiggle it, twist it- or risk breaking the aluminum cover. Now- I just did this on two engines with complete success. http://www.diygokarts.com/vb/attachm...1&d=1329776399
Now- back to that retainer plate/oil diverter. We don't need the retainer, but the other side of the plate looks like it might deflect oil. Instead of throwing it away and risking the unknown, I chose to cut off the retainer portion, and put the rest back on. I used a grinder, you can use snips too. http://www.diygokarts.com/vb/attachm...1&d=1329776960 You may notice I also drilled and tapped a 1/4"-18 NPT hole in the cover for a pulse-pump takeoff and installed a brass hose fitting. If you do this, be sure to thoroughly clean the cover to remove all traces of debris before proceeding. Next, use a small self-tapping screw or other method to seal up the governor shaft hole in the cover. Gently scrape all the old gasket remnants off the mating surfaces of both the cover and engine block. Purchase or make a new side cover gasket and place it over the dowel pins on the block. Apply a light coat of assembly grease on the cam and crank bearing surfaces and lower the cover in place. Work it down gently, again avoiding cocking it on an angle. Having cleaned the bolts apply a drop or two of Loctite #242 blue threadlocker to each bolt. Run them in finger tight and then torque them down in a criss-cross pattern to 9.5 Lbs/Ft. Poof- you're done! All that's left is to fab up a new throttle linkage!
Attached Thumbnails
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9b.JPG  
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Last edited by Doc Sprocket; 02-25-2012 at 07:41 AM.
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Old 02-20-2012, 05:21 PM
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Nice. What is the expected RPM output of the engine after removal ?
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Old 02-20-2012, 05:32 PM
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Entirely depends on when valve flutter presents. With these engines, I don't know yet. The valvesprings are still stock and probably getting tired. I may replace them in the near future, with new springs of the stock rate. Somewhere between 5k-6k RPM is a pretty reasonable expectation. The internals of these engines are fairly impressive and the flywheel is a big cast iron sonofagun. I would definitely call the connecting rod the weak link. However, as long as valve flutter keeps things in check I think the rod will hold out.

EDIT- I have since run this engine at around 5500RPM (calculated based on tire size, gearing, and confirmed road speed) with no valve flutter.
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Old 02-20-2012, 08:01 PM
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Quote:
Originally Posted by toystory_4wd View Post
Entirely depends on when valve flutter presents. With these engines, I don't know yet. The valvesprings are still stock and probably getting tired. I may replace them in the near future, with new springs of the stock rate. Somewhere between 5k-6k RPM is a pretty reasonable expectation. The internals of these engines are fairly impressive and the flywheel is a big cast iron sonofagun. I would definitely call the connecting rod the weak link. However, as long as valve flutter keeps things in check I think the rod will hold out.


i had to delete my private messages so i kinda forgot where we were at with that deal

these old motors seem pretty strong, i dont think it has a weak link
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Old 02-20-2012, 08:36 PM
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That's okay- I just PM'ed you
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Old 02-21-2012, 09:13 AM
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And what would be contributing factors to engine failure due to not having a governor? Cracking the connecting rod, Crank, or wearing out the springs?
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Old 02-21-2012, 05:16 PM
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First- Blue- I did not mean to imply the conrod was weak- I just meant that it was probably the weakest link so to speak. If something is going to fail that may well be first.

Brandon- There are many ways an engine can suffer what we will call a "catastrophic failure". Most often, it is the connecting rod letting go. The flywheel can break, the piston, crank, cam- anything can break under the right circumstances. The key is "the right circumstances". If you do a forum search on governor removal you will find many differing opinions- but the general consensus is that if you take steps to keep the RPM reasonable, and the engine under load, you will most likely be problem-free.

That said, bear in mind that these engines were designed to run all day long at 3600 RPM for the useful service life of the engine. Increase the maximum speed, and wear will also accelerate to a certain degree.
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Old 02-22-2012, 10:26 AM
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Quote:
Originally Posted by toystory_4wd View Post
First- Blue- I did not mean to imply the conrod was weak- I just meant that it was probably the weakest link so to speak. If something is going to fail that may well be first.

Brandon- There are many ways an engine can suffer what we will call a "catastrophic failure". Most often, it is the connecting rod letting go. The flywheel can break, the piston, crank, cam- anything can break under the right circumstances. The key is "the right circumstances". If you do a forum search on governor removal you will find many differing opinions- but the general consensus is that if you take steps to keep the RPM reasonable, and the engine under load, you will most likely be problem-free.

That said, bear in mind that these engines were designed to run all day long at 3600 RPM for the useful service life of the engine. Increase the maximum speed, and wear will also accelerate to a certain degree.
This post is genuis!
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Old 02-22-2012, 04:34 PM
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This post is genuis!
Are you being a wiseacre, or are you serious?
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Old 02-22-2012, 09:08 PM
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Quote:
Originally Posted by toystory_4wd View Post
Are you being a wiseacre, or are you serious?
No, I am serious I finally found a way to stop grandpa from giving me s!&! About taking the governor out of the 8 hp.
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Old 02-23-2012, 04:59 AM
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Hahaha! Alrighty, then!
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Wrench, Wheel, Wreck, Repeat...
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Old 09-27-2012, 06:35 AM
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I just thought I would remind people of this thread. It has gotten buried for a while but is now a sticky
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Old 09-27-2012, 02:23 PM
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Gah. What is it with these mods and their stickies posts? You pat my back, I pat yours is it?
Only kidding, good write up toystory!
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Old 09-28-2012, 12:39 AM
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Good write up, however I will note I've personally seen 4 of these engines pop from Customer governor removal.

I have on a side note seen well over a hundred simply lose compression from over revving. Kids like always are crafty and find ways to speed things up, it usually ends well.

Not to detract from anything you've got here, I just am a firm believer in preaching gearing and safe revving.
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Old 09-28-2012, 01:16 AM
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Gah. What is it with these mods and their stickies posts? You pat my back, I pat yours is it?
Only kidding, good write up toystory!
LOL. Nah....when you are good, you are good.

I seem to remember that you too have a few stickies
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Old 09-28-2012, 04:47 AM
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Quote:
Originally Posted by Blazkowiez View Post
Good write up, however I will note I've personally seen 4 of these engines pop from Customer governor removal.

I have on a side note seen well over a hundred simply lose compression from over revving. Kids like always are crafty and find ways to speed things up, it usually ends well.

Not to detract from anything you've got here, I just am a firm believer in preaching gearing and safe revving.
No doubt. But like anything else here- we are providing the raw information here, and it it up to the individual to evaluate the information and make an informed decision. Many, many times, we have stressed the importance of setting an appropriate gear ratio, and not having unreasonable expectations of an engine.

I would like to know of the mitigating circumstances involved in "losing compression from over revving". Sounds a bit fishy to me...
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Old 09-28-2012, 10:39 AM
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Yes, you are 100% correct. The information is there for people who want, need, and know how to use it. You have done a fine job with pictures and explanation.

Quote:
Originally Posted by toystory_4wd View Post
I would like to know of the mitigating circumstances involved in "losing compression from over revving". Sounds a bit fishy to me...
Overhead valve Tecumseh engines and newer Intek Briggs engines have plastic cams. Over revving and heat will actually wear the lobes of the cam down. End result = compression loss.

Though they were being cheap when they made the engines this way I consider it a grace for most users. Older Tecumseh flathead engines would simply pop a chunk through the front of the block when those popped.

Here is a visual example of said popping. I took this picture a few years back.

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Old 09-28-2012, 10:42 AM
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Quote:
Originally Posted by Blazkowiez View Post
Overhead valve Tecumseh engines and newer Intek Briggs engines have plastic cams. Over revving and heat will actually wear the lobes of the cam down. End result = compression loss.
Ahhh. I see. Given that in this thread I am specifically referring to an Hxx series L-head, I (with steel internals), I couldn't have forseen that.

That said- we really don't know what kind of revs we're talking about, the general condition of the engines, the quality and quantity of lubricant(s) involved... There's so many variables.

Let's face it- anything will fail when sufficiently abused.
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Old 09-28-2012, 10:48 AM
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Yes sir, I had to throw in overhead valve Tecumseh engines because they equate for 70% of karting engines people will run into.
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Old 01-17-2013, 10:44 AM
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Quote:
Originally Posted by Blazkowiez View Post
Good write up, however I will note I've personally seen 4 of these engines pop from Customer governor removal.

I have on a side note seen well over a hundred simply lose compression from over revving. Kids like always are crafty and find ways to speed things up, it usually ends well.

Not to detract from anything you've got here, I just am a firm believer in preaching gearing and safe revving.
As in, the motor blew up?
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