Shaeffer's Little York hit and miss engine

[gbritnell]

I'm wrapping up the build on this engine. I just need to fire it up and make some governor and carb adjustments.
The castings for the head and base are aluminum. The flywheels are very nice iron and there is an assortment of bronze castings for the connecting rod, valve rod, timing lever and some other small parts.
This is a little bit different style hit and miss for the fact that the valves are under the head and have a unique construction and assembly. At first it looks a little crude but when finished it fits the overall look of the engine. Another difference is the timing gears are on the inside of the base casting. This allows the governor mechanism to be closer to the outside of the base and brings the flywheel in closer.
The crankshaft is a built up style but differs in the fact that it was designed with counterweights on the cheeks. With as thin as they are I don't think they will add much counterbalance.
This engine was designed with a set of fabricated points on the side of the engine. It makes it nice because no brackets need to be made to use a Hall trigger. A conventional or electronic ignition can be used.
Now for some pictures.
George

 

[gbritnell]

Up next are the head and valves. This engine uses an NGK CM-6 plug so although it's a little bigger it keeps the cost down. These can be had for about $4.50 on line. Along with the head is the points setup.
George

 

[gbritnell]

I think the governor mechanism is a little more complex than needs to be but it seems to work fine on the bench. It has the traditional spool that slides on the crankshaft. It is moved by a pair of governor weights mounted to a yoke on the flywheel. When the spool moves it pivots a lever that has a ball bearing on one end and the lock plate on the bottom end. When it's in the lock position it holds the end of the exhaust rocker arm in the locked out position. I did change the spring setup for the governor. It had as much complication as the other bits and pieces so I simplified it by making an adjustable rod that is loaded with a spring. It is a very easy job to change out the springs to get the desired rpm for the engine.
George

 

[gbritnell]

Next up is the crankshaft and timing gears. As was noted the timing gears are inboard of the crankcase base which narrows up the whole affair.
George

 

[gbritnell]

This engine has a cast crank cover made from aluminum. It's a nice feature that keeps the oil from slinging about. The bad thing is there's virtually no way to oil the big end of the rod without removing it. You can use a squirt oil can but with that you have to hope it will wick into the bearing.
That's about it. If anyone is contemplating building this engine be prepared for some drawing interpretation and calculation. (90% of the dimensions are fractional). I'm pretty good down to most 1/32 dimensions but save for 1/64 I don't know any of the others. With a calculator it's no big thing but more of just a pain in the butt.
Oh yes, here's one last picture. It's the fuel tank. It is plumbed with 5/32-48 MTP fittings. The drawings call for an inline check valve but Coles didn't have one in that size. When I get ready to start it I'll see if it needs one, if so I guess I'll have to make it.
Thanks for looking,
George

 

[moanaman]

Very interesting motor unlike any I have seen in Australia, but I am no way an authority on small commercial IC engines. well done.

BarryG

 

[metalmad]

what a interesting and lovely engine!!
that remote spring affair takes some getting used to, but only having one adjustable spring sounds great to me :bow:
Pete

 

[bearcar1]

Terrific work you do George. I 'missed' buying a set of these castings years ago at a show, are they still being sold or have you had this set for some time? It seems to me there was another model that looked like it would be fun called "The Woodpecker". Ah, so many models to build and so very little time. :'(


BC1
Jim

 

[Diy89]

Great engine!

 

[gbritnell]

Thanks guys,
Jim, the castings are still available. They are being sold by Ministeam.
George

 

[HPME]

Nice engine George!
I built one of these several years ago, nice running engines.
Daryl

 

[Brian Rupnow]

Lovely engine George. I would think that having an adhustable governor spring would be a real asset.---Brian

 

[higby]

George,

Greetingd from Sydney. I need your help.
Partly inspired by your post and pictures I purchased the plans and basic kit from ministeam and have been busy on this delighful project fo about 6 months. I am no engineer and have found this little engine very challenging not helped by having to convert most of the mesurements to metric.
Now I am stuck! Is there any chance of one more image with the flywheel on the Cam side removed so I can see the cam arrangement. For the life of me I cannot work out from the plans just how the cam is tightened. Also, do you have any suggestion for the fixing of the boston gears to the shafts with any method other than Locktite? I am contemplating a tiney grub screw to hold the smaller of the two tight on the shaft. This will however necessitate drilling the tiny hole through the face of the teeth!
Your advice would be deeply apprecitaed.
Warm regards
Richard. Sydney, Australia.

 

[gbritnell]

Hi Richard,
Boy it's been a long time since this thing was built. I went back through my old photos and every one I took was posted in this thread. I also looked at the drawings, which I updated for Ministeam, and the only thing I can tell you is what's on the drawings. For the timing gear on the crankshaft due to the other components stacking up there is really no way to fix the gear other than possibly with a small tapered key unless like you say you would have to put a tiny grub screw between 2 of the teeth. When I redrew the drawings I basically put all the required dimensions on it plus took them from fractional inch to decimal inch but the assembly was from the original drawings. As far as the cam my drawing shows a 3-48 grub screw. You could probably use a 2 mm.
gbritnell

 

[gbritnell]

Hi again Richard,
Not wanting to leave you hanging I did a second look at my pictures and I see that the timing gears are inboard of the side wall of the engine. Being that the crank gear is trapped between the crank cheek and this wall you could very well use a small key. It wouldn't have to be tapered as the gear can't go anywhere. I hope this helps.
gbritnell

 

[higby]

George, you are a gem Mate.

Thanks for your response. I chose to make this little engine because it was really small. To the aging eyes of a home machine hobbyist this was probably a mistake for that very reason. Anyway, I took the Ministeam plans, scanned and printed them out at A3 size and aided by your images launched myself into the thing. Notwithstanding that my workshop language has deteriorated markedly over the 6 months, I am about two thirds complete.

Your suggestion of a tiny keyway gives me another option which I had not thought of. Both choices will need the skill of a watchmaker if I am to avoid mucking up the little gear. Just debating which of the two options will weaken the small gear the least and which will be the easier to make by this amateure. Aah, and it's a grub screw that secures the cam. Excellent.
Thanks again George.
Warm regards
Richard - Sydney, Australia.

 

[higby]

Hi George,

Sorry to bother you again but still need your help.
I have the finish line in sight and just need to make the carburetta which will be an eyesight challenge. But also have a problem concerning the cams.

There are two on this little engine. The main Rocker cam "N" and a smaller cam called K - "Switch Cam" which is basically a 2/3 circle with a flattened side. Its this latter cam I have the problem with. I can see no reason why this cam is needed as both the rocker arm and Points arm work together. It would appear that the pointed end of the switch arm needs to engage with this small cam wheel but not knowing the reason why leaves me not knowing how to set the thing up. I can only guess that's is a back-up for the main rocker arm.
I have poured over your images but unfortunately no image with a wheel removed thus exposing the cam setup.
Much appreciated.
Regards
Richard - Australia

 

[higby]

As you were George,

Not to worry as I have worked it out. My stupidity. With further thought I realised you need two cams, one for the points and one for the exhaust valve.

All the best.

Cheers from Sydney, Australia.

Richard