Hi Guy's I have an old stle Sachs 4.2. It has the coil on the spark plug and then runs to the front of the case, then there is one wire running from the front of the case. Question, Is this the old style ingnition or do I need a ingnition box for this. I will try to get a photo of what it looks like

Thanks, Dave

Picture please

here it is, thanks guy's

That's one of the best RC engines ever, there is no better engine made today, other than weight..
It's a magneto engine, no battery needed...the extra wire is a ground used to kill the engine...
Save yourself some aggravation, that carb is so old there are probably no rebuild kits available...
Get a Walbro SDC 80 if you can find one...

There should be kits available for that carb. Haven't seen a Walbro on an airplane engine yet that didn't have the major parts available for it. If not, as suggested the SDC-80 is pretty much the carb of choice for that engine.

That engine is bolted to a Byron Purr power muffler / mount. If it is in good shape, I would be interested in buying it at a reasonable price. I agree .... great old engine. Powerful and they'll run forever.

If the magneto makes a spark, rebuild the carb and run it. No battery required.

The carb is an ancient Tillotson HU series..With plastic parts....

Thanks Guy's
Its like being in a engine manufacturing center. Its going in my Corsair and when I got it I was told it was new, So I will run it and see how she does and if I need to up grade to a new carb I will go with your suggestions.

Great help, thank you

Dave Can anyone give me a suggestion on what size three blade prop

Fly that Byron Corsair with a good 24-10 until you're use to flying it then and only then and after you've debugged everything about the engine and airframe ....worry about what size 3 blade prop will work well. Use what is proven then move on from there.

CJW123 sure sounds like Ralph to me?!

I found the carb, but which one

Thanks Dave

http://www.ordertree.com/cms/Emab/413.html

SDC-80 is a good starting point for a 4.2

Im not 100% sure , but I think the sdc80 has been discontinued. There may be some setting around still.