Throttle governed engine

[crueby]

Victory!!

[gbritnell]

Brian,
I have been following along and am a little perplexed. You built the engine and it ran fine. At that point you put it on the shelf only to be taken down to power your edge sawing machine, but it wouldn't run.
I don't mean to play the devils advocate here but what on earth happened from running to all the things that were required to get it rerunning?
Curious minds want to know!
gbritnell

[Admiral_dk]

Very happy to see that you finally succeeded 

[Brian Rupnow]

George--I think it was a voodoo curse.  Well, not really. If I had pulled the heads off and lapped the valves a bit more FIRST I probably wouldn't have done all the other things. When an engine runs well and gets put up on the shelf for a few years, then doesn't run properly when you get it down off the shelf, you start eliminating possible causes. The engine had spark. The engine had fuel. The engine refused to run properly. I pressure tested both cylinders with compressed air thru a fitting screwed into the sparkplug hole, and  they seemed to hold pressure adequately. I did every "easy" thing that I know how to do to make the engine run properly, and none of them worked. At that point it was either abandon the project or start digging deeper. For whatever reason, this engine seems to be very very particular about the valves sealing 100%. Ah well, it's January and I don't have a whole lot going on anyways.---Brian

[Craig DeShong]

   we ALL knew you’d figure it out.  Congrats.   

[Art K]

Brian,
Woohooo....and I'll tip one to a running engine.
Art

[Brian Rupnow]

I have restored the hand built carburetor to the engine, and it is running much better. I have decided that the engine would benefit greatly if I were able to manually adjust the ignition timing while the engine was running. The points will now mount to the red plate with the red handle. The red plate rotates on a central boss on the gear case, and by loosening the green capscrew I can advance or retard the timing to find the "sweet spot" where the engine runs best.

[Jasonb]

Brian, you may want to alter that so that the long red screw also acts to loosen/trighten the bracket then you don't need two hands to adjust things. Another option is to add a spring or friction washer under the cap head screw so you can just move the bracket by the lever but it won't move due to vibration.

[Brian Rupnow]

That is a good idea Jason. I may put a spring washer under the head of the socket head capscrew.

[Brian Rupnow]

I had three grandchildren sleeping over and a sick wife, so I've been running around like a chicken with it's head cut off today.--Did manage a couple of hours this afternoon to whittle out the "Timing plate". The points shown are an old pair that I keep on hand for "set-up" purposes. The brass bit in the center will actually be attached to the front of the brass gear cover. When I have the handle attached to the timing plate, this will allow me to tilt the plate in one direction or the other, to the limits of the curved slot, to adjust the timing while the engine is running.

[Brian Rupnow]

Here we have the timing plate and handle installed on the engine. The concept is that you set the ignition timing as close as possible with the plate mounted as shown in its neutral position.Then, when the engine is running and warmed up, you loosen the bolt that is in the curved slot, and this lets you rotate the plate and points mounted to it a few degrees clockwise or counter-clockwise. This retards or advances the ignition timing until the engine is running in it's "sweet spot", then lock down the bolt in the slot.

[Art K]

Brian,
I did a similar thing on my Upshur engine. I put the points on a round disc with a I think 20 degree slot in it. The back side has a step that fits into the hole bored in the crankcase, keeping it in that same radial plane. With the screw holding the plate in place.

This is the best photo I can find.
Art

[Brian Rupnow]

I haven't ran of with the gypsies, nor anything nearly as exciting. I've been plugging away on this engine, correcting faults and trying to get my head around a few things. Like Bob Seger's song, "Nightmoves" I've been "Working on mysteries without any clues." I've had everything apart right to the bare bones and built it back up again, checking clearances and tolerances. I have no problem starting and running the engine. The problems are inconsistencies in the way it runs each time. Some of the new features I've added cascade. I added the manual ignition timing plate and lever, and it works fine---but it eats up 1/4" of clearance on that side of the engine. The answer to that of course, was a new pulley and starter hub, with an annular slot on the engine side 1/4" deep to fit over that #10-24 bolt head that holds the ignition points in place. I have eliminated everything that would potentially cause a problem except for the cams themselves. They are a direct copy of the cams Malcolm Stride used on his "Bobcat' and "Jaguar" engines. I made the single cylinder "Bobcat" engine with enough changes to rebrand it the "Canadian Cub", and although it ran satisfactorily it also shot vapour out the mouth of the carburetor while running. I ordered a new set of "Rimfire" sparkplugs yesterday from Roy Sholl at S & S Engineering.  If I decide that the duration of the cams is too great and is causing the vapour discharge from the carburetor, I'm not sure if I will go so far as to make new cams or not. When I first built this engine, I didn't put any key in the starting hub and crankshaft on that side of the engine. The engine ran so well and with so few problems that I thought I would get away with it. Of course, it has came back now and bit me on the arse, because with all the messing around trying to change this engine over to  a "Throttle governed" style, the starter hub was slipping on the crankshaft.  So, this morning I broached a keyway into the starter hub and set the entire engine up on my mill table with the crankshaft locked against rotation and milled a new keyway into the exposed end of the crankshaft. The saga continues-----Brian

[Brian Rupnow]

Today we have some good news and some bad news. The good news is that the trouble with the right hand cylinder was indeed the sparkplug. I haven't got my new plugs from Roy yet, but I did discover a 1/4-32 sparkplug in one of my other older engines and used it to replace the sparkplug in the right-hand bank. The engine now runs fine. Who knows!!!---It might have been the bad sparkplug that was the problem all along. The bad news is that the engine doesn't want to accelerate while under load. The governor and linkage works exactly as I had planned. When I spin the engine over with my electric drill, the governor weights immediately fly out, closing the throttle right up to the adjustable "stop", the engine starts, and everything runs fine. When I put a load on the engine, the governor reacts exactly as I had planned. The engine slows down, the tension spring pulls the weights of the governor back to center, the linkage opens the throttle. BUT--then the engine stalls. If I engage the load very slowly, sometimes the engine will keep up, but nine times out of ten the engine just stalls out and quits. I more or less know why, but I'm not sure what I can do about it. In a conventional "old style" automobile with a carburetor, when you step on the gas to open the throttle, the accelerator pump squirts a stream of gasoline directly into the carburetor throat to keep the mixture from "leaning out" which would cause the engine to stall. In my miniature carburetor, there is no provision for an "accelerator pump". If I richen the mixture to my carb by unscrewing the needle valve, the engine won't run at low rpm. If I start the engine under load, it will run, but it doesn't like it. The vapour coming out of the carburetor throat has lessened considerably, so that may have just been a function of running too rich and having a bad sparkplug.

[Jasonb]

Have you got an adjustable  air bleed on your carb, plenty of model engines use them to give a richer mixture at lower revs and tick over. Look at The Nemett one if you want something to copy.