Erratic Timing
FWIW.
Even though the '68 distributor used roughly the same advance as your plate has (30 crank degrees), the '68 vacuum advance provided more than the replacement pod you bought. The range spec'd in the book suggests something around 24 - 26*.
What mechanical curve you can use for your engine will depend on the details.
If its got EGR and/or smog cam (where the exhaust closing was extended) that's going to change things a little.
And if its later 4 barrel equipped 318 (police or truck) different again. Probably a longer initial advance, and slower secondary advance.
Then based on that, its not too hard to match an appropriate vacuum advance.
You can get clues on what the 318 is from using the paint color, intake, date info cast on the block, and of course engine number of you can see it.
FWIW.
Even though the '68 distributor used roughly the same advance as your plate has (30 crank degrees), the '68 vacuum advance provided more than the replacement pod you bought. The range spec'd in the book suggests something around 24 - 26*.
What mechanical curve you can use for your engine will depend on the details.
If its got EGR and/or smog cam (where the exhaust closing was extended) that's going to change things a little.
And if its later 4 barrel equipped 318 (police or truck) different again. Probably a longer initial advance, and slower secondary advance.
Then based on that, its not too hard to match an appropriate vacuum advance.
You can get clues on what the 318 is from using the paint color, intake, date info cast on the block, and of course engine number of you can see it.
