Model Engine Building

[Jerry B]

I Have Build Two Model Hit&Miss Engines Got Them Runing,But They Give Me Alot Of Problems Getting Them To Run, The Cam Is Ajustable,And The Points Are Adjustable, The Vavles Are Seated Good, I use Electic Motor To Get Them To Run,It Takes Foreven, Can Some One Help Me ,Thank You Jerry B

[Andrew Mackey]

What type (hit&miss, TG, 2 cycle, 4 cycle, Other) of engine is it?
Andrew

[Ted Utess]

Hi, Jerry---I too am a self-taught model engine builder. Someon once told me that when the machining wqs done you were half-way to a running model. This has been proven to me many times. All the adjustments are VERY TOUCHY and on has to be DELICATE with all of them. The one thing I have found that isn't mentioned enough is VALVE TIMING. The exhaust valve wants to open BEFORE bottom dead center and close JUST AFTER TOP DEAD CENTER. If you can get it to run at all, leave the EX valve adjustment loose and slowly change it, the engine will pck riht up in most cases.---TED

[Heller D. Davis]

Jerry: I have been building model engines for twenty four years and one of the most important items you must have is good compression. The end gap for the rings must be small, not over .oo5. The rings must fit the grooves with minimal side clearance and the valves must seat 100%. If you have good compression all of the other factors can be adjusted to make the engine run properly. The flywheels should bounce back when rolled up against compression and released. Also the model must not be to tight on the bearings. It should rotate with no binding or drag. Also the valve timing mentioned earlier is right on. Exhaust must start to open before bottom dead center and close just after top dead center. I run all my models with the ignition timing set at about three degrees before top dead center and use coleman camp stove fuel for fuel. You also have to have a check valve in the fuel line to hold the fuel up to the mixer. Hope this helps

[Capt,n John]

Do you think running a Model Hit& Miss engine on propane would be any more easy to start and adjust? How about a sniffer valve. Where can I get plans for a sniffer valve? Thanks Capt,n John

[Capt,n John]