1972 MTD 990 with 15 hp cast iron B&S. I recently picked up this tractor and am trying to get it to run smoothly. I had taken the front engine shroud and the points cover off just to have a look at things. When I tried to start the engine it produced a large yellowish/white spark from the rear shroud bolt to the metal gas strap every time it turned over. See photo. The engine never started. Also, when I removed the spark plug wire it stopped producing the spark. I don't know what I did but it started when I removed the points cover.
I replaced the points and condenser but did not reinstall the cover. When I tried to start it again the large spark was gone and it started and ran for 4 or 5 minutes. I would love to know what could have caused this large spark. If anyone has any ideas I would like to hear them. Thanks.