Here is a MSD system I recently picked up.

Comes with

MSD-6AL
Blaster Coil
MSD distributor 8556
Two step module selector.


Basically my question is. I have a Non-CC carb setup.
Can I still use this MSD distributor? and everything else?
If I can ditch the vaccum dizzy I would be okay with that.

 

You won't have the street advantage of vacuum advance, but otherwise, it will "work".

 

So what would be a disadvantage of running all of the above?

The thing is, I want a revlimiter... period. I ruined my first engine build by overrevving substantially. I understand you can run the 6AL with my current distributor, but would be such a waste to have a nice distributor like this lying around collecting dust.

 

Cruise fuel economy would suffer without vacuum advance.

 

Please elaborate? I am not sure sure if I am on the same page.

What I think you are saying is that the timing will change due to the vacuum with the old style.

With MSD it would I guess stay constant instead of variable?

 

The distributor only has mechanical advance. You'll get the advance you need under power, but under light throttle conditions such as cruising down the highway, when vacuum advance would give you additional advance, you won't have it so fuel economy won't be quite as good.

Back in "the day", I had a mechanical-advance-only distributor in the hybrid 302 I had in the '57. I would get about 11 mpg with it. I later changed the distributor to one with mechanical and vacuum advance, and I'd get 13 mpg.

Back before overdrive, lock-up torque converter, etc.

 

So, What would be some advantages then of the mechanical only?

I think what I will do is start out with the MSD distributor because it directly plugs into my ignition system. Drive it around for a month or so, then I will throw my vacuum distributor in and record the difference in performance and then economy.

Anyone else chime in on some of this? I believe everything you say Five7, just like to have some diversity, if there is some to give.

 

Mechanical Advance is more predictable. It gives the same amount of advance every time, regardless of any outside input. This is preferable for drag racing, where running the exact same time over and over again is your goal. Fuel economy and part-throttle driveability mean nothing

A vacuum advance is flexible. It provides a more optimum spark curve while under light loads, which provides fuel economy. Not only do you have the mechanical advance in the distributor to give you your wide open throttle power, you have the vacuum controlled advance to give you a better spark curve while cruising around.

You should never put parts on a car "just because". It is a nice distributor, but why not hook up the ignition system to your stock distributor, sell the msd, and buy something that will actually make the car go faster?

 

Well regardless whether or not I use the distributor I will use the MSD-6AL period. (I need a rev limiter)

So one more vote for vacuum advance eh?