If it looks like this, its a Mallory built version.
View attachment 1716171784
Changes don't do what you think they they will do. In particular changing the advance also changes the initial spring tension and degrees out before the secondary spring joins in.
Advance should begin at 1000 rpm or less. Stock, non-smogged 318 should start advancing by 800 rpm.
That's too much timing at 2500 rpm to use with vacuum advance.
2 bbl 318 is a pretty efficient engine. Doesn't need that much advance until high rpm.
I'll promote reading up on
what timing does, a post from this thread:
total timing reading accurate with no load?
Since your timing measurements started with TDC, lets plot them onto a chart with a factory 318 distributor that was meant to be set at TDC. Some others graphed
here.
View attachment 1716171783
For your 318, if you want to learn how the adjustments inter-relate, would be worth changing the advance from 14 to 18 or 20. This will reduce tension on the primary spring, and also delay the effect of the long loop spring. Retest and the advance should begin at a lower rpm. The response off the line should have more pep too.
Good info. Should also test for what vacuum is needed to begin obtaining vacuum advance.
That's fine
For the 340 - No.
For that an advance curve more like the Chrysler built MP distributors came with, or that Rick works out here.
https://www.forabodiesonly.com/mopar/threads/distributor-curve-help-needed.496183/#post-1973532835