70 ragtop

My Feedback: (24)

Looking for a little help with an A&M 4.2 mounted to a Byron Purr-power muffler. Running a Walbro WJ1 carb with C&H ignition(gold box), coupled advance

Engine is mounted in a Byron P-51, bought it used years ago, fit engine to the plane and never got around to finishing. Finally getting it wrapped up, put a carb kit in it, and was presently surprised when it fired right up. Flying field is about an hour away, so I ran a couple tanks thru it around the yard, high power runs-idle, fast acceleration ect....it just ran great.

I drove up to the field, it fired right up and seemed to be running great. Taxied out, tail came up and when I pushed the throttle up, it started to miss, like it was really rich.

Brought it home, amd of coarse it fired right up and seemed to run great. Put a Menz 24-10 prop on it, ran three tanks thru it, running it around the yard, idle-full throttle-idle-mid throttle, ect, it ran great.

Drove back up to field, engine fired right up, but would not accelerate to full throttle, it sounded super rich coming off idle. Messed around with it and by leaning both screws, got it to accelerate to full throttle. Warmed it up and richened it back up so it wasn't running lean. Flew one flight, it ran great. Went to fly again, it did the same thing, only I couldn't get it to clear out this time. If I left it at full throttle it would sit there sputtering/missing like it was really rich, then it would clear out and accelerate fine. Playing with throttle different ways didn't seem to help

Brought it back home, same thing. Once in a while it would clear up and go to full throttle all by it's self. Once hot, seemed to run ok, but if you go to idle then try to accelerate again, it same thing. Put a new plug in it, same thing

Put another carb kit in it, bought the lever tool, even changed the nozzle check valve per the Walbro chart for accelerating rich. Checked fuel system, no issues found, no bubbles to carb when running. Timing was at 29.5 at full throttle, and TDC-1 at idle, have since bumped that up just a touch. I've never had an engine start so easy, and it starts every time. You would never guess it had issues it has the way it starts. I'm not sure if it's missing, or rich anymore. The C&H ignition has 4.9 volts to it( checked with a meter), and is powered by a Ultra IBEC Ultra IBEC - Tech-Aero Designs LLC , but I haven't monitored that while its running yet. Ground from CDI to engine is solid, not sure what to do next

Hoping you guys might have some ideas
Thanks

All Day Dan

My Feedback: (5)

Try it with a separate ignition battery. The IBEC may be dropping the voltage to the ignition module when the engine is running. Dan.

2walla

My Feedback: (10)

Check the balance on the prop. Some of the 4.2 carbs had an enrichment circuit in them with a spring and ball bearing and would get real rich if it had some vibration in it..

Lifer

My Feedback: (1)

Pulse leak?

70 ragtop

My Feedback: (24)

Thanks for the feedback guys
I tried a 4 cell nicad in place of the IBEC tonight...no change. After I shut it down, it wouldn't restart...no spark. Plugs on CDI are new, and look good. Guess the CDI was on it's way out
Will give CH a call tomorrow

CK1

My Feedback: (60)

My bet would be either the source coil is bad or there is crack in the plug boot and it is starting to carbon track to ground , shortest path thing.
I think sending it to Adrian (CH) is the right choice .

70 ragtop

My Feedback: (24)

Was $60 for a new unit, have a new one on the way