2F dieseling at shut off. (1 Viewer)

[rainingagain]

There are many reasons for dieseling. What do the plugs look like? Are they showing sign of getting excessively hot? When you turn the engine off an fuel air mixture could be ignited by a hot plug. You mention the timing bb is at the bottom of the window which I believe indicates the timing is advanced past spec. Typically dieseling is from hot spots in the cylder. Carbon build up can increase the compression ratio, advanced timing creates more heat. then running lower octane fuel, will all contribute to the issue. Does this engine ever see faster speeds or higher rpms for any length of time? Maybe a different heat range plug might help too. Sometimes a good flogging can blow the carbon off the top of the pistons too, but that's up to you.

When I was wrenching and someone brought in a older carb'd vehicle that was running rough and we suspected carbon buildup, we'd tell them to go out and try to get it up over 100mph then come back if there's still an issue haha. Give a good flogging like you said. It really does help.

 

[island45]

I discovered the problem last week and solved it immediatley. With Spring in the air I have been working on the Foyota and chasing down problems. Seems there is a hold down clamp for the dizzy as well as a squeeze bolt to lock the rotation in. Last year I noticed the hold down was missing so I did some grinding on a washer and used that. It seemed to tighten it up, but not really. What I wasn't seeing was the 12mm bolt that locks the rotation. The dizzy had been retarding itself gradually over time and running worse and worse. The dieseling problem was outa control. I'm happy to report that it shuts down without a stutter, starts extremely well hot or cold and even with the infamous chinacarb it runs like a Swiss watch. Yay!
In re-reading this thread I have to give Mattressking a gold star for mentioning the timing right outa the chute and reminding me again later in the thread. In my ultimate wisdom I did not bother checking because I had set it carefully a few weeks before and was confident it was correct. At 70 years old next month I'm afraid the 40 years of cruiser wrenching may be over-ruled by memory loss. Anybody seen my 12mm box end?