Re: adjustable vacuum advance canister....1986 258
A couple of cures -
Convert to an HEI - easy, very effective - then use an adjustable advance to get it dialed in. See the other post this morning about how to dial it in.
Or - with what you have -- make a little limiter stop inside the distributor to limit the travel of the breaker plate. It takes a little creativity. Max - total advance should not be more than 35 @ 3000. And it should come in slowly and evenly.
Use PORTED VACUUM.
IF you have the Ford type distributor that has a big hex nut on the diaphram, it's adjustable for sensitivity too.
Remove the hex nut - use washers as shims on the spring, or remove some. Removing them makes it LESS sensitive - puts more spring against the vacuum.
Instead of using the original carb and "Nuttering it" best to replace it altogether. The "Nutty" way is just setting it to full rich all the time - Mickey Mouse! At todays gas prices, one tank wasted will buy a nice used MC2100.