Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: Setting Timing
Regardless of what might be the "optimum," the timing in your engine now is too far advanced, assuming that you don't have some other problem such as carbon buildup, lean mixture or third-world gasoline.
You can probably get a cheap test tachometer, but shouldn't really need one. Set the engine down to a reasonable-sounding idle and set the timing. See how it runs. Then repeat as necessary.
My 258 likes anything from about 2 to 10, although it will ping at the higher end of the range, and loses power at the lower end. Generally engines run best with timing just below the pinging threshold.
Just retard it a few degrees at a time until the pinging goes away. That will probably solve the run-on too. If it doesn't, the mixture probably is too lean overall.