Design and build side-shaft hit and miss engine from bar stock

[CFLBob]

Brian, I've lost track. Does the engine have the piston with O-ring?

If it is, what is the O-ring made of to withstand that heat?

Thanks.

 

[Brian Rupnow]

The piston has a Viton o-ring now, which is a heat resistant material. I'm not sure if it is a polymer or something rubber based. See post #183.

 

[Brian Rupnow]

Today I am messing around with the hit and miss function of this engine. It definitely works. Engine fires up, gains rpm., up to a point where the governor lever tilts down and the threaded rod blocks the rocker arm from releasing the exhaust valve. Engine goes into miss cycle, and rapidly slows down until rocker arms is released. Exhaust valve is allowed to release, then engine tries to run again but doesn't quite make it. I have found that my anti-backflow valve isn't working, so while the engine is missing, all the gas in my gas line is running back into the tank. I broke down this morning and ordered an anti-backflow valve from a hobby shop in Mississauga. It has a neoprene ball in it, which should do a lot better at keeping the gas in the gas line.

 

[Brian Rupnow]

I will probably work on the gas tank now, because everything else is finished. Measurements show that a tank 1" wide x 1.5" tall, x 5 1/2" long will fit the location I have shown in the 3D model. There are a number of ways I could go about building this tank, but since I have no equipment for welding aluminum I may make it out of steel rectangular tubing with ends and filler neck and outlet tube silver soldered into place.

 

[Brian Rupnow]

I'm having an easy day today, so thought I would build the gas tank. Laying on the chair you see the rectangular steel tube 1" x 1 1/2" x 1/8" wall, a piece of 1" x 1/8" stl. flat bar, a brass or bronze pipe cap, and a 90 degree black iron pipe elbow. I have already cut the extra length that I didn't need from the elbow, by screwing it to a 1/2" straight pipe nipple and cutting it off in the lathe.

 

[johwen]

Hi Brian,
Try a smaller carburetor bore size and i think you will find it will run slower and pick up petrol easier. With piston rings I make my own and put two rings in the groove with the gap set at 180 apart I use 2 narrow rings i a .0625 ring groove seal very well and hold compression. Cheers John

 

[Brian Rupnow]

With the little bronze or brass pipe cap gets screwed onto a matching pipe nipple and then set up in the lathe, it changes quickly from an ugly duckling to a pretty gas cap.---And yes, I know my lathe is pig dirty. I can do things two ways. I can use my lathe dirty until the project ends and I thoroughly clean it up, or I can keep it nice and clean and never do any work.

 

[Brian Rupnow]

This is as much as I'm going to do today. That pipe elbow has been welded to the endcap on the inside with my mig welder. Not continuous---just three good tacks to keep things from moving when I solder that end with the elbow onto the end of the rectangular tube. I have to solder the elbow to the endplate at the same time to get everything leakproof. I'm going to mig weld those little "bolting ears" also.

 

[Brian Rupnow]

Today we have a 99% finished gas tank. It isn't pretty but very little of it is exposed when it is bolted into place. I may actually splash a bit of gasoline resistant chassis black paint on it before installing it.

 

[Brian Rupnow]

TADA!!! We have a finished and installed gas tank. Everything fits. I will hook up the pipe from the other end when I get the anti-flowback valve that I have ordered

 

[sieby]

The piston has a Viton o-ring now, which is a heat resistant material. I'm not sure if it is a polymer or something rubber based. See post #183.

Hi Brian - i am from Australia - how can I get hold of the plans for the Hit and Miss Engine. Nev Sieby

 

[Brian Rupnow]

I have been notified by Canada Post that my new anti-backflow valve will arrive tomorrow. At that point, the voodoo will begin. Setting up the governor on a hit and miss engine is kind of a black art. On other engines like the Kerzel and the Odds and Ends hit and miss, the only variable is the strength of the governor springs. On this engine there is going to be a whole whack of variables. First I start out with the assumption that my flywheels are heavy enough. I'm sure that if anything, they are probably too heavy, but I don't really know. This leaves a few other variables. One is the strength of the compression spring that holds the governor normally disengaged. Another is the amount of engagement between the governor latch rod and the rocker arm. A third may possibly be the second threaded adjustment rod that determines how far out the governor weights are allowed to fly. Should my carburetor adjustment be richer, or leaner. I hope to figure all of this out in the coming week. I've came a long way on this project since it began four weeks ago. Everything to this point in time has been successful. The engine runs (and keeps running). The water reservoir doesn't leak. I will find out tomorrow if there are any leaks in my new gas tank. (I've tried it with tap water, but Coleman fuel will leak thru spots that tap water won't.) Wish me luck guys, it's been a fun ride.---Brian

 

[Brian Rupnow]

Sieby--I will be selling plans to this engine for $25.00 Canadian funds, but your a bit too early. I still have to get the hit and miss part of things sorted. I just checked and there are about 65 drawings. Some of those will be redundant, as I have switched carburetors a couple of times. I accept Paypal paid into my account there which is under my email address [email protected] I do advise you to wait a couple of weeks until I have had a chance to "clean up" the engineering files and get the hit and miss function sorted out. If you DO send any money to my Paypal account, please state which engine plans you want, because I have quite a few different ones.---Brian Rupnow

 

[JohnBDownunder]

Still looking great Brian.
One thing I don't seem to see is venting of the gas tank. I would think it must be there somewhere or a partial vacuum will stop fuel flow.

• Tank cap a loose fit?
• Or tiny hole in the cap that I cannot see??

I have new specs after the cataract opp so???
John B

 

[Brian Rupnow]

Johny my boy, you're getting old and blind like me. Either that or else I didn't have the hole in there before I posted the picture. anyways, There is a 1 mm hole thru the center of the gas cap so the tank doesn't vacuum lock. I used to not put that hole in the gas cap, and just loosen the cap to run the engine.--It didn't work. Those caps are quite heavy, and are screwed to a tapered pipe thread. Engine vibration will cause the cap to screw itself shut to the point where the engine won't run.

 

[Brian Rupnow]

My incredibly small anti-backflow valve showed up today. It's not very big, but it doesn't have to be any bigger. This goes into the gas line between the carburetor and the gas tank to keep all the fuel from running back into the tank when the engine is in "miss" cycle. I had built one of these, but it didn't work consistently and I didn't feel like messing with it. Mine was made with a 3/16" diameter steel ball. I think this bought one has a neoprene ball.

 

[JohnBDownunder]

Ha Ha, Brian,
Yep started my 78th orbit of the sun last August. Strange isn't it that most of us do not think as old folk should? I figure I'm thinking in about my 40s or so. Age becomes clear to me tho whenever I attempt anything physically demanding. So as far as possible I avoid that dastardly stuff.
Messing in my shed sure beats work. I LOVE being retired.
Oh, and a 1mm hole may or may not have been present, and I could easily miss it. I'm always getting in strife from SWMBO for not seeing tiny specks on the kitchen bench etc.
John B

 

[Brian Rupnow]

Engine is running steadily and consistently now, using fuel from it's own tank. Plumbing the tank got a little crazy but it all worked out well and incorporated my new anti-backflow valve. nothing appears to be leaking. It's setting beside me here on my office desk, running like crazy. Next thing will be to set up the governor.---Brian

 

[Brian Rupnow]

Doom, despair, and agony on me---the damned purchased anti backflow valve from Sullivan #S756 doesn't work. Not only doesn't it work, but when I called Great Hobbies in Mississauga where I purchased it, they won't send me another one, claiming I have to ship this faulty one back to them at my expense ($11.00) before they will send me a second valve to try. I am at an impasse now. Not sure what to do. Their customer service man is supposed to call me back this afternoon. If he doesn't make me happy, I may drive to Mississauga and pull his arms and legs off!!!

 

[Brian Rupnow]

I just got the call from Great Hobbies telling me that this Sullivan valve will only operate if there is "back pressure" from the line on the outflow side of the valve, to seat the ball. I think they ---well--it doesn't matter what I think. Fact is, I'm out $35 and don't have a solution to the problem. I can try building another one myself, with a smaller ball (My first one had a 3/16" diameter ball) which may have been too heavy for the venturi vacuum to lift of the seat. If anybody knows of a source for a purchased anti backflow valve that doesn't rely on back-pressure in the line to make it work, please tell me.---Brian