mech advance or vacuum advance?
 

swaping to car..combo is in sig..im learning as i go:D ...so what is better and why?what are the advantages of using a MSD mechanical advance as oposed to an 85 distrubter?

and what is the diffrence between points and elctronic?i am carbed illiterate..im too young(23) to know that stuff..i grew up with EFI:D

You and I are in the same boat. I am soon to be 23 and also grew up with EFI. I did a 300 6 cyl to 302 swap in a truck I had and went carb but nothing performance just stock replacement stuff. The drag motor is carbed and my guru here suggested I go vacuum adavance know because of my level of knowledge, affordability, and ease of work. I am going to use a MSD 6AL box. Good thin about that is it can be used with either distrubutor. I got a 85 dist at the parts store for $85 with cap rotor and base. Not to bad a price I think. I would suggest the vacuum advance due to availibilty and ease of operation. I understand wanting optimum performance but I dont want to buy parts that wont benefit me yet if I dont have to.

Brad

Vacuum is better for a street car, when cruising at part throttle the timing doesn't advance so you'll get better fuel economy and at part throttle acceleration the curve will advance faster from the change in vacuum, whereas a mechanical advance is controlled by the engine rpm.

For a drag car that doesn't need fuel economy, driveability or part throttle response and spends most of it's time at full advance (3000+ RPM) then mechanical is the way to go.

If you do go with vacuum advance, find someone who knows how to re-curve distributors, it's becoming a lost art but it makes a big difference.

BTW I'm only 24 and since the mustang mags don't talk much about carb tuning (except for some full blown race motors) I've learned a lot from HOT ROD and from other books about tuning carbs.

I have never seen a distributor that had vacuum advance, and did not also have mechanical advance. If you are asking if you should just use mechanical advance as opposed to using both, it depends on what you want to use the engine for. If you are building an everyday driver, I would recommend using both. If you are building a weekend only racer, i'd just use mechanical.

Take care,
-Chris

Is there an exact science or science at all for changing the springs that are in the MSD distributors for altering the mechanical advance. I just stuck the distributor(MSD8582)in as it came. I have several other springs and what not. Would I really get any noticeable performance gains from messing with it a bit?

Yeah, there is a science to it, actually. The lighter springs allow the full advance to be acheived earlier, whereas the heavier springs put the full advance off until a much higher rpm. When you want the advance to reach full depends on everything else, like your gears, your other engine mods, etc.

Take care,
-Chris

Makes sense. Thanks! I guess I will play with it a bit and see what happens. Although knowing me I'll screw something up. Later.