after being away from my glow plane for about 4 years i find my self having to relearn some stuff. i learn to fly on my sig senior than switched over to electrics for the last few years. i just installed a new magnum 70 4-stroke on it and started the engine break-in process by the book and after about 25 minutes of break in time, i went to restart it again and nothing. i checked the glow plug and its good. i think maybe the fuel lines came off in the tank becuase when i pulled off the fuel line to the carb and cranked the engine with the electric starter no fuel came out. am i doing this right. i dont wanna remove the tank if i dont have to. the first 10 minutes of run time it smoked heavily and vibrated pretty bad. i repeated the process 3 more times in 5 miniute intervals leaning it 1/4 turn each time. the wierd thing was i thought i would see it running a little better each time i leaned it in but it ran the same. rough and heavy smoke. any help please?

First, I would check to see if you can put mild pressure on the tank using the line from the needle valve and the line from the muffler (Block one and put a bulb on the other). That will tell you if there is a cracked or broken line or a crack in the tank. Make sure that you have the correct line going to the muffler and to the needle valve. Was the tank drained and clean before you put the Senior away? If it had some old manky oil in it from last decade's fuel, I would expect strange results. The vibration might just be an out of balance prop, or residue of old fuel in the tank. I would make sure that you get good fuel delivery first. Glow plugs can look good but have a few contaminated coils that make the motor run poorly...this is not unusual in breaking in new motors, but this sounds like fuel delivery issues to me.

Man oh Man, is is this a familliar story. The mag 70 carb is a bit different than any of the others I had. My Mag 70 was doing exactly what your are describing. Two or three days at the field with the "experts" helping only made things worse. First, the Mag 70's mix needle screws out to a stop vs in. The standard screw it in to a stop and then out 2 1/2 turns flat doesn' t work with this engine. Check the manual for initial needle settings. Start again from there. Tune up the top end, then the idle, back to the top and back to the idle. Starting from scratch is what you need to do. Once you get it tuned in, you will be very happy with the engine. Mine is the best running of the bunch, and I have two 91's , a 70 and a couple 52's as well as some O.S . If you need the inital settings, I'll dig out my manual and send them to you.

Don

Added
If you need the tune up sequence, let me know. Reading back, you can't get the over rich condition, IE heavey smoke with leaks in the fuel delivery system. You are getting to much fuel. Start from scratch on the carb with the settings in the manual and then adjust from there.

Don

To reset the low speed needle valve screw to the factory setting, follow these procedures:

Open the carburetor barrel completely.

While holding the barrel open, turn the needle valve screw OUT (counter-clockwise) until it stops.

From this point, while still holding the barrel open, turn the needle valve screw IN (clockwise) 4 turns.

This is the factory setting.

It's backwards from most other engines? Ok. That's a bit odd, but once known, I guess those with Magnum engines can live with it.

Most OS four strokes are the same way

i put a OS f-plug and she is running a little better and not shaking quite as bad. i just restarted the break-in process. wish me luck ! i need it ! glow fuel smells so good after messing with the electric stuff for soooo long !