I understand the basic principles of what makes each different, but I wanted to hear from some of you guys which you prefer AND why.

Locally there's a good deal on a new MSD distributor with vacuum advance and I'm wondering if I should buy it for when I swap my intake. Is it ok/possbile to plug the vacuum advance and just tune it with springs? I thought this might limit adjustability or something since it was designed for use with the vacuum canister.

I have a stock distributor with vacuum advance right now, but in the future (hopefully not too long) I will be swapping a 4 speed in my car and I am not sure if that affects my decision on this.

My distributor now doesn't seem very precise, as the cap doesn't lock down tight with the attached clips.

 

Vacuum advance changes ignition timing based on engine LOAD, less vacuum, higher load, less advance wanted. Centrifugal advance changes timing based on engine SPEED, regardless of the vacuum level. At higher speeds, highway for example, cruising, vacuum level may be insufficient to allow enough spark advance; that cuts fuel economy. Thus, the centrifugal INCREASES advance while cruising, regardless of what the vacuum level is.

Bottom line, IMO, is it's nice to have both! imp

 

Thanks for your response. Unless someone here thinks I shouldn't use vacuum advance I'm going to go for it, it's being sold for half what it costs and it's brand new. It requires use of a ignition controller, so I'll be looking at those soon too. Luckily I just made huge upgrades to my electrical system so I'm ready in that sense.

 

I ran an MSD billet dizzy that was mech only for many many years daily until It stopped advancing reliably rather than rebuild it I went to see what else I could find. One guy that I talked to was down right pissed off that I ran mech only on the street and told me "shame on you" he really wanted me to buy a vac advance system... I was like **** this guy and kept looking.

I went with the MSD E curve which does have vac advance which I use. So rather than 32 deg at freeway speed I run 42 deg (there abouts) at freeway speed and when I punch it, it rolls back to 32. I didn't see a much noticeable difference in fuel mileage and as you would expect none in power. The fuel mileage differently inst worse but its probably only 1mpg better. I have also found the MSD E curve to be quite reliable despite looking scary its been very solid and doesn't have fly weights to get sticky or need rebuilding.

So yeah if you can get a good working vac dizzy by all means run it.

-Gun

 

Thanks guys! I'll be getting new distributor Wednesday.

 

Hey is this white powdery oxidation anything to be worried about? There was an invoice with the distributor, it looks like it could have been sitting awhile. I read that this is due to moisture that can't escape the distributor? If what I'm reading is correct it's no big deal. Can a hole be drilled in cap to vent moisture?


In this next one I tried wiping off the oxidation, the magnets or whatever they're called look fine.

 

I would brush it off with a soft brush of sorts and go about your business.

You'll need a good timing light now and probably advance spring and bushing set. I bet that bad dog isnt all in until like 3500 with those springs 2000 to 2500 would be better

 

ok, now all you have to do is set the initial (idle) timing AND the timing curve to get the most benefit from it.

 

Once I brushed off the magnets, I saw no signs anything would be wrong. It came with a red cap, which I didn't want, so I painted it today. Prices are high for msd caps! I did a vacuum canister test today to see if everything actuated correctly and it looked good. I will certainly get a spring kit to dial everything in once that time comes. Now I am on the lookout for a low priced 6a or 6al2 ignition controller and good quality coil too.

 

Painting a distributor cap is not recommend. The paint absorbs moisture and will cause the terminals to arc at best. Could you not get a cap molded in the color you wanted?