Dieseling engine

Posted by AdStriking6061@reddit | aviation | View on Reddit | 6 comments

I have a 1976 Beech Sport 150. Had the mags overhauled around 100hrs ago. Just did an annual on it and timed the mags to 25⁰ BTC. engine shuts off perfectly with the fuel cutoff. but when I use the ignition switch and turn it to off it tries to die for about 20-35 seconds before it shuts off. It has a lycoming 0-320-E3D with a Marvel Carburetor MA-4SPA and slick mags. any suggestions at what to look at would be great.