# ENGINE SPEED GOVERNORS



## Brian Rupnow (Apr 27, 2019)

Lets talk about engine speed governors. I am well acquainted with flyball governors and flywheel mounted governors to control the lockout rod on hit and miss engines. I have built many of them with varying degrees of success. Having just completed my sideshaft horizontal engine, I am interested in putting a governor on it, similar to the governor envisioned by Edgar Westbury who originally designed a governor as an "add on" to the Centaur engine. This governor fits onto an extension of the sideshaft and movement of the governor weights control how much the carburetor throttle-plate is opened or closed, by a linkage between the governor and the throttle on the carburetor. It is a centrifugal governor, controlled by the speed of the engine. Let us assume that I want the engine to run at an idle speed when under no load, but as the load increases, the engine will open it's throttle proportionally to compensate for any load which makes the engine want to stall. In order to do this, the governor weights would have to be at the full extent of their travel, outwards away from the center shaft when the engine is running at idle speed. As load from a driven device caused the engine to slow down, the weights would begin to move closer to the shaft because of spring tension and a lessening of centrifugal force. This in turn would move the lever, causing the throttle to open more and increase the engine speed to offset the slowing caused by the load.----SO--My question is, where would those governor weights lie in relation to the central shaft when the engine was shut off. Would they lie close to the central shaft causing the carburetor throttle to be "wide open", but with very weak springs so that they fly out quickly to their full extent and close the throttle plate to "idle" condition as soon as the engine goes from zero rpm to idling speed? I can't really see it working any other way. Does this mean that when I start the engine I am always going to be starting it with the throttle plate in the "wide open" position, and as soon as it starts the governor closes the throttle to "idle" speed?


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## Cogsy (Apr 28, 2019)

This could be tough to put into words but I'm thinking about a (sort-of) two-part throttle. So you have a manual throttle which you move, which sets the maximum available throttle position. Then you have a 'traditional'  governor which closes the throttle as weights are thrown out at high speed. I have seen a similar thing on old lawn mowers where the throttle is opened manually via a cable (terminated with a spring that can be over-ridden) but there is a 'sail' on the throttle which is affected by the airflow from a fan on the flywheel. As RPM increases beyond maximum, the airflow to the sail overcomes the spring force and the throttle closes, but when RPM drops the spring opens the throttle again. In this way you can start the engine at low throttle position, then open the throttle to whatever position and the engine won't rev past what you've set the governor to. Basically, you'd have two springs competing with each other attached to the manual throttle and the governor.

You could set it such that the engine is always idling but obviously you wouldn't get maximum power out at idle and I'd guess that enough of a load to be full throttle at less than idling speed would probably stall the engine before it could respond.


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## gunna (Apr 28, 2019)

On full size engines I am familiar with, the default position of the governor when stopped is full throttle as you surmise, Brian. I don't suppose you really mean "idle" speed just a suitable low speed for normal unloaded running.
Ian.


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## Brian Rupnow (Apr 28, 2019)

I modelled the governor based on Edgar Westbury's drawing, and it doesn't look that bad.


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## Brian Rupnow (Apr 28, 2019)




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## canadianhorsepower (Apr 28, 2019)

Hi Brian ,
Nice idea, but before you spend a lot of time on this. Read more about unloaded RPM and loaded RPM on a Briggs Stratton engine
the RPM IS THE SAME but when the engine is slowing down the governor spring will kick in to keep the same "unloaded RPM to a FULL loaded RPM. This will never affect your idle RPM. The best way for you to prove this, set your unload rpm to 2500 then load your motor so your governor can kick in and keep the same RPM


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## Brian Rupnow (Apr 29, 2019)

My original idea was to build this governor and add it to the sideshaft horizontal engine. The sideshaft engine runs so well as it currently sets that I have decide not to change anything on it. I may however build the governor as a "stand alone" unit and drive it with a coupling on the end of the horizontal sideshaft camshaft.


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## Brian Rupnow (Apr 29, 2019)

Just as I thought, this governor lends itself very well to being a stand alone unit. This is something that could be attached to the end of my engine baseplate and coupled to the end of my camshaft. Having it's own ball bearing in the support brackets would take all the loading away from my engine cam bushings.


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## Brian Rupnow (Apr 29, 2019)




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## Brian Rupnow (Apr 29, 2019)

Knowing my limitations as a machinist, I decided to make the flyweights from two pieces.


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## Brian Rupnow (Apr 29, 2019)




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## Brian Rupnow (Apr 29, 2019)

A very pucker-worthy job so far. I started out earlier today with a crusty old chunk of 3" diameter shaft. So far--So good.


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## Brian Rupnow (Apr 30, 2019)

Somebody said they were confused because they didn't see any springs on the flyweights. Here they are. I just want you to know that springs are one of those things that I find absolute S.O.B. to model. I can do it, but it takes me a long time, and since I only do it about every three years, I never remember quite how to do it.


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## Brian Rupnow (Apr 30, 2019)

We got PARTS!!! These two flyweights came out very nice. Not really the weight of a fly though. More like maybe a full size rat. I have to go rake leaves for a while now before wife shoots me. Might get a start on the parts which bolt to these later today. There is a heavy rain warning for Barrie and surrounding area for tomorrow, so tomorrow will definitely be a work in the shop day.


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## Brian Rupnow (Apr 30, 2019)

Jeez, what an old pussy I am!!! Raked leaves for half an hour and I have a blister the size of a dime at the base of my thumb. Rake hanFirst layer of skin is gone. Second layer is red as  an apple. Work related injury. Guess what my son. I have your weekend all planed out for you!!!


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## nel2lar (Apr 30, 2019)

Brian
They make gloves for us wossies.
Cheers
Nelson


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## Brian Rupnow (Apr 30, 2019)

Today I made the second part of the flyweights. They don't look like a lot, but it's taken a good share of my day.


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## popnrattle (May 1, 2019)

Beautiful work, Brian!


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## werowance (May 1, 2019)

so the 2 springs on the weights,  different spring tensions is how you would adjust the governor to be appropriate to the size of the engine / desired rpm?  sort of like the advance weights in a chevy hei distributor?


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## Brian Rupnow (May 1, 2019)

Yes Werowance--more or less. there is one more spring that I haven't as yet shown, which helps or works against these two springs and is adjustable so that you can "tune" the rpm at which the weights move. This gives you control over the engine speed set points.


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## werowance (May 1, 2019)

the more I look at it the more I realize its almost exactly like the governor on my farmall super A tractor.  the throttle has a spring on it so that when I pull the handle say half way the governor can override the half way on the carborator and pull it futher on say 3/4 of the way to compensate for load change.  on yours the solid link would not give you that ability but since you don't have a throttle handle anyway on your engine then it wouldn't matter.   and on that note of being like my Farmall,  its a bugger to adjust correctly after tear down so it doesn't constantly surge under idle...


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## werowance (May 1, 2019)

just to share a farmall governor pic for comparison


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## Brian Rupnow (May 1, 2019)

At this stage, the governor works. I had it up on the mill chuck, and it does indeed open and close as planned with rpm changes. I was going to make a video, but there isn't anything to really see yet. When I get to the stage of levers moving I will post a video. Something which isn't shown in the 3d model yet is the external counter spring. It has adjustable tension, and is used to fine tune the rpm at which the governor kicks in or kicks out.


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## Brian Rupnow (May 1, 2019)

This shows the governor counter-spring which adjusts the governor to engage at different rpm's. The governor is shown as "not engaged" in this model. When the governor begins to spin and "engage" the long blue lever moves to the left at the top end, and a link from it goes to the throttle lever on the carburetor. By turning the knurled adjuster wheel and putting more tension on the red counter-spring, we can control when the governor engages.---I think!!!


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## stragenmitsuko (May 2, 2019)

Nice , governors have always been a bit of a "dark area" to me . 
They work , or they don't work ,on lawnmowers that is , but that's about all I know about them .
I'll be following along , and beautifull work as usual brian .


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## canadianhorsepower (May 2, 2019)

[QUOTE=" it's a bugger to adjust correctly after tear down so it doesn't constantly surge under idle...[/QUOTE]
surging at idle has nothing to do with your governor, it's a carburetor issue. Governor only work at high RPM. matter of fact
your governor is always trying to keep your motor at idle


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## werowance (May 2, 2019)

i dont want to take over Brians thread but if you bump the throttle or goose it let it drop back to idle it will keep bouncing until it settles down.  the governor keeps goosing it.  there is an adjustment on the side of the governor for the farmall - there is a baseline setting for it however you still have to fine tune it and its just a hair of a turn one way or another to get it spot on and then you can goose the throttle or bounce it and it will rev up and drop back down and maybe the governor will only bounce once.  but then under load the governor does it thing properly.  that fine tune adjustment is what I had a time with when I rebuilt my tractor and put in all new ball bearings and springs and such in the governor.   but it works great when adjusted properly. however when its to loose or to tight it will set there and bounce back and fourth rev rev rev rev rev for a long time before it settles down.


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## Brian Rupnow (May 2, 2019)

I believe that when a governor does that, it is said to be "Dithering".


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## canadianhorsepower (May 2, 2019)

[QUOTE=" "Dithering".[/QUOTE]

Dithering is a term use in hydraulic and pneumatic circuit,
it is cause by al almost equilibrium in pressure


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## werowance (May 2, 2019)

Thanks Canadian for the PM that's good info to have.  Brian,  I really like this build.  it could easily be adapted to many different engines.  and the adjustment you modeled explains how you will be able to overcome the dithering or surging or what the heck is called    I call it a pita lol.


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## Brian Rupnow (May 2, 2019)

I didn't do a lot today because I was running all over town with good wife doing things that had nothing to do with machining. But--While we were out running around town, I bought a $20 stick of bronze. Did I ever tell you how much I really HATE machining bronze?-Nasty grabby damned stuff. Made the sliding sleeve and three thrust washers this afternoon.


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## Brian Rupnow (May 3, 2019)

No machining today, had too many other things going on. As I sat playing with the governor as built last evening, I came to a sudden realization. When I move the flyweights out away from the center shaft, as they would do from centrifugal force, the fingers contact the end of the sliding spool and make it travel in a linear movement along the center shaft. However, when I move the flyweights back close to the center shaft, there is nothing to make the sliding spool move back to it's original position. Now it is a lot clearer to me about why the counter-spring is attached to a separate lever. The counter-spring pulls the lever back, which causes the shaft to revolve and that movement  also moves the two other arms which are connected to the governor thrust collar. The thrust collar which is trapped in one end of the sliding spool forces the sliding spool back until it is once more in contact with the arms on the flyweights. This is going to be very interesting to see in operation.


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## Brian Rupnow (May 3, 2019)




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## Brian Rupnow (May 3, 2019)




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## Brian Rupnow (May 4, 2019)

Bit by bit the plate brackets are coming together.


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## Brian Rupnow (May 4, 2019)




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## werowance (May 5, 2019)

is that a filing machine in the back ground?


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## Brian Rupnow (May 5, 2019)

Werowance--That is an oscillating spindle sanding machine. I just bought it about 4 months ago for smoothing inside corners on things I machine. The spindle comes with five different size drums and rotates and goes up and down while it is rotating.


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## Brian Rupnow (May 5, 2019)

Another day--another part. With the help of two young grandsons we finished up the leaves today. Thirty one bags of oak leaves down to the road for the township to pick up. The grandsons age four and seven really thought it was cool riding around in the empty cart behind my lawn tractor. The baseplate which I finished this afternoon looks a bit different than the baseplate in the model. That is because I was trying to make as much as I could from "reclaimed" 3/4" material, and I didn't have a piece big enough to make it the same as the model. That's okay though.--I will make the missing piece of the baseplate a "bolt on" part.


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## nel2lar (May 5, 2019)

Brian
That is a thing of beauty. One fine job on design and build.
Nelson


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## Brian Rupnow (May 5, 2019)

Nelson--I have always been interested in mechanical feedback speed control devices. It will be interesting to see this one work.


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## nel2lar (May 5, 2019)

I do not know if it would make a whole lot of difference but the spring mounts on the side of the governor if they were cut on an offset they could be tensioned or loosened with just a turn on the holders. That is one special governor, I fell in love with it. Thanks for sharing.


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## Brian Rupnow (May 6, 2019)

Here's a little tip on threaded spring tensioners like the one in my model. If you make them as a single threaded shank with an eye at one end, they will rotate when you tighten or loosen the adjustment finger wheel. If however, you make them as seen in this model with a double shank and slot the piece they pass thru, then they won't rotate when you are trying to adjust spring tension.


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## Brian Rupnow (May 6, 2019)




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## nel2lar (May 6, 2019)

Brian
A work of art. Looking real nice.
Nelson


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## Brian Rupnow (May 6, 2019)

Edgar Westbury called up #20 swg. for the springs which keep the flyweights together. 20 swg (which I assume to be "standard wire gauge") is listed as being 0.036" wire diameter. The closest I could buy to that is actually 0.038" diameter wire. It feels like it would take seven men and a bulldog to pull the flyweights apart with these springs in place, but we're in "Try it and see" mode here. I'll let you know how that works out. The rather puny looking tension spring on the left is one I had selected out of a 200 piece spring kit that I had, but it looks pretty wimpy beside the .038" springs.


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## Brian Rupnow (May 6, 2019)




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## Brian Rupnow (May 7, 2019)

This governor has four arms with hubs on them. I decided that the easiest and most accurate way to make them was to make the arms and hubs as separate pieces and then silver solder them together. These pieces are way too small to hold in the correct relationship for soldering, so I made up a couple of jigs from short pieces of .093 " round-bar, some round 3/16" stock, and  scrap aluminum. The aluminum is counterbored by the amount which the hub runs past the arm it is mated with, and the 3/16" round rod keeps things from tipping and getting crooked while being soldered.


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## Brian Rupnow (May 7, 2019)

Well, that didn't turn out too shabby at all!! Everything fits where it's supposed to. I'm coming right down to the short strokes on this governor. I only have a couple of pieces left to machine.


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## Brian Rupnow (May 8, 2019)

And here we have a video of the first dynamic test of the governor mechanism. I am pleased with the results. I still have to make an adjusting screw and knob for the counter-spring, but it seems to work exactly as I hoped it would.---Brian


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## canadianhorsepower (May 8, 2019)

Brian Rupnow said:


> And here we have a video of the first dynamic test of the governor mechanism. I am pleased with the results. I still have to make an adjusting screw and knob for the counter-spring, but it seems to work exactly as I hoped it would.---Brian



the video is very nice, do yourself a favor,remove the spring from your counter weight, all you need is one


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## Brian Rupnow (May 8, 2019)

An observation---The governor seems to want to start moving the arm at about 650 rpm. This initial test was made with the counter-spring at it's maximum setting. I am assuming that if the counter-spring was adjusted to not have so much tension on it, the arm would start to move at a lesser rpm. (Hopefully I will find that out tomorrow.) This governor was designed to run off the cam shaft of an engine. The part that I find interesting is that my engines generally idle at about 1000 rpm, and there power band is around 1400 to 1500 rpm. The cam shaft rotates at 1/2 of the crankshaft rpm. --So, it seems that the governor engaging at 650 rpm fits right in with a 1300 rpm crankshaft speed. This could be purely coincidental, or it may be that Westbury actually made this governor, and the spring size he specified for the flyweights is based on actual testing at the time it was designed.


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## Brian Rupnow (May 9, 2019)

I lay in bed last night thinking of just how this throttle was going to work. If there is anything a bit fishy about this throttle governor, it is the fact that when the engine is shut off, the governor parks itself with the throttle held wide open. I don't like the idea of having to start the engine with the throttle wide open and waiting for the governor to spin up to speed to close the throttle. The answer would be to find a way to disengage the governor when the engine was at rest. Without going thru a complex bunch of maneuvering to install a clutch between the governor and the engine camshaft, I have an idea. If the link between the governor and the throttle arm were made as shown here, I could use a mechanical means to lock the carburetor throttle in the closed (idle) position. The governor would still work as expected, but instead of moving the throttle arm, the spring in the linkage would simply compress and not move the throttle arm. As soon as I unlocked the mechanical throttle over-ride, the governor would once again turn to it's normal function. thinking--thinking---


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## canadianhorsepower (May 9, 2019)

[QUOTEI . If there is anything a bit fishy about this throttle governor, it is the fact that when the engine is shut off, the governor parks itself with the throttle held wide open. I don't like the idea of having to start the engine with the throttle wide open and waiting for the governor to spin up to speed to close the throttle. -

[/QUOTE]

Brian that's the way a governor work on all small engine . As soon as your engine will start that governor will kit in.
but then again that spring on your counter weight simply make it harder for it to reac.
nice work


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## Brian Rupnow (May 9, 2019)

More dynamic testing this morning showed that what I thought is true. The less tension there is on the counter spring, the sooner the lever moves at less rpm of the spindle.)


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## Brian Rupnow (May 9, 2019)

This is going to get very interesting. I ordered a 3/8" Lovejoy coupling today, and I will use it to connect the camshaft of the horizontal sideshaft engine I just finished to the governor, all on a common base. The engine will eventually drive something with a varying load to see how the governor responds.


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## Brian Rupnow (May 10, 2019)




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## Brian Rupnow (May 11, 2019)

Just for the heck of it, at the end of my very long install a dishwasher at my oldest son's house day, I thought I would try this set-up. Driving the governor at 1:1 ratio off the crankshaft to see what would happen. What happened was that even at idle speed the governors swung out to their largest travel and no amount of tightening or loosening the counter spring would make them return to the "parked" position in close to the center spindle. Okay--driven at 1:1 off the camshaft they will be turning at half this speed. I'll let you know what happens when driven from the camshaft.


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## Brian Rupnow (May 12, 2019)

Today I rearranged things a bit and drove the governor with a 1:1 ratio from the camshaft. Very pleased to report that when driven off the camshaft, the governor will both engage and disengage by changes in the engine speed resulting from changes in the throttle setting. Yesterday I tried this same trial by running the governor off the crankshaft, but  the governor was driven so fast that it would not disengage regardless of what engine speed I was able to achieve.


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## Brian Rupnow (May 13, 2019)

So there we have it, and its a beautiful thing. The engine is bolted to the sub base. The governor is just setting in the correct position, but not bolted down yet. I will wait until I have the Lovejoy coupling in place between the engine and governor before I drill and tap the holes which mount the governor. I did some more testing of the governor attached to the camshaft via pulleys and belt like shows in my last video, and I'm quite comfortable now that the cam shaft turns at the right speed for engagement and disengagement of the governor with slight variations in engine rpm.


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## Brian Rupnow (May 13, 2019)




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## Brian Rupnow (May 14, 2019)

The link that ties the governor arm to the carburetor throttle arm isn't going to be rocket science. Just a turned brass end and a piece of 1/16" diameter bent wire. My Lovejoy coupling won't be here until Thursday, so maybe tomorrow I will make the machined brass part of the link. I won't bend the wire until the governor is bolted down in it's final position, as dictated by the coupling.


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## Brian Rupnow (May 17, 2019)

We are ready to Rock and Roll!!! My Lovejoy coupling came in this morning and I immediately went down to Canadian Bearings and picked it up. Some of you may wonder why I waited until I had the coupling before I drilled the holes in the sub base to mount the governor to it.--Well, it's a matter of trust. I simply don't trust the solid models that are available from suppliers websites.---and in this case, my distrust was quite justified. The solid model I downloaded from Lovejoy had the center spider at 0.280" thick. In reality, it measures at about 0.400" thick. If I had positioned the governor based on their 3D cad model, all of my drilled and tapped holes would have been out by half a hole. Two years ago, a company I was doing some work for had me design about 15 dies based on the customer supplied 3D cad models. The dies were designed, machined, and sent to the customer. The parts they made from the dies were all way out of spec. What the Hell??? Turns out the customer parts had went thru 3 or 4 revisions and nobody updated the solid models. They fired the guy responsible at their end and the guy I was doing the work for had to eat about $30,000 in rework of all the dies. I have finished the link between the governor and the carburetor to what I hope is the correct length and soldered the ends on. I'm going to go eat a bowl of soup  and give the Loctite holding the pivot pins for the linkage time to set up a bit, and then start things up and see what happens.


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## Brian Rupnow (May 17, 2019)

It works!! I had to take one of the springs off the governor body, because it just wasn't sensitive enough with two springs on. Now I can start the engine and let the governor adjust the rpm the engine runs at in a no load situation. When I push hard on one flywheel with my thumb to load up the engine, you can see and feel the governor reacting to the load by opening the throttle to give the engine more gas to keep the rpm that the governor wants.  I will now try and make a video of this so you can see the action happening.


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## Brian Rupnow (May 17, 2019)

This is the video which shows the governor working to maintain a constant rpm at the engine, whether it is in a "no load" situation or a "loaded" situation. I am pleased, it does work quite well. I may, in future, hook the engine up to some machine I build, but for now my thumb works pretty good as a "loading device".---Brian


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## nel2lar (May 17, 2019)

Brian 
Congratulation is in order on this one. You earned your title of engine designer. She is a beauty and runs very nicely, the governor is doing everything it is made to do. Now take a well deserved break.
Again, you did it.
Nelson


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## TonyM (May 18, 2019)

That works really well. Great job.


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## stragenmitsuko (May 18, 2019)

A good load for this would be an ac generator .
The rpm determines the frequency , wich is usually 50 or 60Hz .

Then the alternator could be loaded with an ac motor or some light bulbs and the governor would
have to work to maintain rpm .

Great work brian


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## ShopShoe (May 18, 2019)

Wonderful,

I enjoyed the entire design and build of the engine, and then the governor.

Congratulations on a very successful build and thank you again for all your postings.

--ShopShoe

(Tongue in Cheek)

What stragenmitsuko said above: I think a generator and a variable load on it would work great with what has been built so far, but I understand you really love mechanical devices and not electrical systems. What about a fluid (water?) system that would require a pump, a reservoir, and maybe a needle valve or two? (Made out of  clear plastic so you can see the fluid?)

--SS


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## Ctmouse (May 18, 2019)

Brian Rupnow said:


> This is the video which shows the governor working to maintain a constant rpm at the engine, whether it is in a "no load" situation or a "loaded" situation. I am pleased, it does work quite well. I may, in future, hook the engine up to some machine I build, but for now my thumb works pretty good as a "loading device".---Brian



Great Job thanks for sharing! 
Rick


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## Brian Rupnow (May 18, 2019)

Thank you all, gentlemen. That all went very well, with no re-do's or scrapped parts. I do have a really nifty over-center clutch to power from the engine output, but at the moment I don't have much machinery to put on the other side of the clutch. I really appreciate it when people comment on my builds. ---Brian


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## Brian Rupnow (May 18, 2019)

And for Luc---You were right. The governor only needed the one spring to work correctly. I built this governor almost exactly to the original drawings by Edgar Westbury, as shown on the first page of this thread, and he showed two springs, so that's what I did. I have always followed the principle that if I`m not really sure, go by the drawing. If I have to tweak things a bit after something is built, I will.---Brian


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## JohnBDownunder (May 19, 2019)

Thanks once again for an enjoyable, educational thread Brian. Any of your threads are a magnet for me.
John B


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## bigearl91 (May 19, 2019)

Very well executed. Thanks for sharing the build with both of these projects.


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## Brian Rupnow (May 19, 2019)

I looked around my shop for flat belts, but I only found this short little guy to run my over-center clutch.


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## canadianhorsepower (May 19, 2019)

Brian Rupnow said:


> And for Luc---You were right. The governor only needed the one spring to work correctly. I built this governor almost exactly to the original drawings by Edgar Westbury, as shown on the first page of this thread, and he showed two springs, so that's what I did. I have always followed the principle that if I`m not really sure, go by the drawing. If I have to tweak things a bit after something is built, I will.---Brian


Thanks Brian, very nice work, as usual. Now if you want to try something that will get your governor working
so fast, you want notice the change in RPM ,but only the arm reaction. Remove the second spring on your counter weight. All you will ear
is engine noise( working harder) and no RPM change. anyway THUMB UP


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