Base timing. Really ?

mopower440 said
well im not sure why on the above posts it was stated that the limiter plate was hurting it..?

If you're talking generally, then generally

Mattax said
Don's plate stops the advance. To then get the initial and maximum where they should be, the distributor has to be rotatated. That shifts whole curve up. Alternatively the springs can be messed with and thats not easy for most folks. The secondary spring is the most critical and hardest to find for an advance that's been stopped early.

Welding up the inside of slots it cuts off the bottom of the timing curve. For most electronic distributors, that's it, all done. Curve is still correct when the initial is set like a pre-CAP engine (or higher initial if its hot cam).

360 Tune Up

Try this.
Sketch out a timing curve using a factory initial timing and rpm.
Then take the same curve and but start it with a higher initial timing. Just like if the distributor was rotated to get higher initial.
Sketch that out.
Where does the rest of timing ending up?
What happens when vacuum advance is added at normal driving speeds?

Now go back to the first timing curve you sketched.
Draw a line across where you want the initial to be.
Now where does timing end up when vacuum advance is added at normal driving speeds?