Where do you have your vacuum advance hooked up?

All good stuff, thanks for all the input. So is there a difference in vacuum cans for ported vs manifold vacuum?? Say like a stock points dist. in '70 was hooked to ported vacuum correct? Are the newer distributors ie: mopar performance electronic ones, firecore, FBO, set up with a different advance unit that is designed to use manifold vacuum? or does it basically just boil down to how much vacuum your engine makes at idle and what it prefers timing wise?

I followed the tips in the Book from Don at FBO I use one of the mech advance plates.

I set my base timing at 14* with the mech advance 18* - 32* total. 88-440 truck-whiplash cam 230/245 @.050 .518/.518 with the edelbrock RPM duel plane intake....running the holley 440 STREET dominator single plane intake I run the dist locked out on 0* timing set at 34* IIRC

I installed a new reman 318 1st of January. got a new stock replacement points dist. -ditched PCV for a evac system. -stock tbi roller cam/headers/q-jet.

set the timing at 10* adjusted carb A/F ratio with vac gauge for highest reading re-adjusting curb idle to 750 rpm.

hooked can up to full vac port on carb and that raised curb idle but cleaned up the idle and very smooth. re-adjusted to the 750 rpm.

nice smooth daily driver 16.5 mpg no ping anywhere in the rpm range and have dropped back to 87 pump gas..still no ping under load.

after reading the book I understand it a little better. at first with the big lumpy cam I had no power and heated up driving.

once I got the initial timing advance to where the engine wanted it and limited the mech advance it tuned right up and became street friendly.

got to get the spark ahead of the slow burning pump gas so it all burns in the cyl not the exhaust tubes. it had killer exhaust fumes that had me thinking it was way rich but it was really going lean. which in the book it said this is cause by it burning all the oxygen and leaving the unburned fuel trying to burn as it goes out the exhaust tubes thus making the engine temp rise and header tubes glow red with lots of smelly fumes.

so after 20 yrs of ported vac with mostly stock cams/dist/daily driver junk I have them on full vac and very happy with the results set up this way.

this is the first time I have had a 318 on 87 pump gas not PING! over 1/2 throttle from a stop light in traffic running a 195* thermostat.

I have the same FBO complete system (with coil) on my 64 Belvedere's orig stock 383. PIA to get it to stop pinging at WOT. Don says my carb is too lean & I must use manifold vacuum. I don't know if the orig afb has manifold vacuum so he says to find a port on the intake. I tried adjusting the can & still no help. Might ditch the system & go back to the dual point with pertronix dizzy.

I guess the way I see it is if you have an engine that starts fine with the static advance setting and it idles good, then ported vacuum is the way to go. If you have an engine that idles good with more advance than allows for starting with out kickback, then manifold vacuum is the better one since you can retard the timing to allow it to start and then have it advance a set # of degrees with the vacuum to where it idles good. So at WOT, both manifold and ported vacuum signal will drop significantly and mechanical advance takes over at that point correct? Sorry for all the questions, just trying to educate myself on this subject

PIA to get it to stop pinging at WOT.

At WOT, there's no vacuum advance, so I would look at the total timing, fuel, or both.

Ebooger has written many articles explaining why you want (and need) as much as 45-50 advance during cruise for max performance and mileage.

34 total at WOT is fine, need the extra 15 from vacuum advance when cruising / light load.

Did you previously run the dual point with no issues?

IIRC there is a # stamped on the arm of vac can IIRc you get about half that # in mech advance. so you can search out a can that will give the advance needed.

my understanding is with a stock dist on ported vac it adds to much mech advance. up to 50* or more.

the can is adding mech advance and the weights are adding more mech advance when rpm increases.

I tried last night to swap it onto ported and the results were poor.

I removed can from full vac, rpm drops, adjust back up to 750 curb idle, hook line to ported vac, adds no mech advance, test drive and 1/2 throttle from stop it pings and spark knock.

change back to full vac on can and adjust curb idle back down to 750, test drive, no ping or spark knock.

dist & carb working together may be what I stumbled upon on mine.

on my junk, following the steps in Don's book and not the way I have always done it fixed a lot of things I have put up with for yrs.

I will be hooking up the vac gauge on ported vac to see what it is doing at 1/2 throttle from a stop. and get a WOT reading.

I haven't seen many replies about compression ratio I run close to 11-1 compression on pump gas so I wouldn't want anything over 34 degrees timing EVER on my engine. I wouldn't recommend any type of advance until we get all the engine specs.
40-45 degrees of advance would cause some major detonation on a high compression street/strip engine. That's where the caps start walking and the cracks start opening up

Gus