can you add a vac advance on stock A distributor

[mike657894]

I had an idea to mount a vac canister from another distributor to the stock A distributor. Maybe with a bracket. Will it have enough oomph? Can I get one with enough stroke? Is there a reason it would just not work no matter what? just seems like it could be a 20$+time upgrade and one less thing for people to learn that I teach how to drive the car . Has anyone here done this and succeeded or failed?

[C26Pinelake]

What are you trying to accomplish ? Wayne

[Charlie Stephens]

A model B distributer with a centrifugal advance might be a better choice or one of the aftermarket distributers with something built into it already. Note the Model B distributer requires a Model B timing cover or it will be a little more work in the timing.

Charlie Stephens

[C26Pinelake]

Originally Posted by Charlie Stephens

A model B distributer with a centrifugal advance might be a better choice or one of the aftermarket distributers with something built into it already. Note the Model B distributer requires a Model B timing cover or it will be a little more work in the timing.

Charlie Stephens

So I ask you Charlie, what will the end result be as compared to a stock A? Wayne

[Dodge]

There is also the aftermarket automatic advance unit that goes inside the valve cover in the disributor/oil pump drive.
And no a vaccum advance can't be made to work on a stock dist.

[Dick Steinkamp]

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Vacuum advance only provides advance under high vacuum conditions. This is primarily light throttle cruise, trailing throttle (especially downhill) and idle (if manifold vacuum is used rather than a ported vacuum). This would not solve the need for the engine of additional advance with an increase in RPM.

[40 Deluxe]

It CAN be made to work! Ford did it from 1949 thru '56. Vacuum advance only. They used a combination of ported vacuum and venturi vacuum to get the right advance curve for all RPM and load combinations.

[Dick Steinkamp]

Originally Posted by 40 Deluxe

It CAN be made to work! Ford did it from 1949 thru '56. Vacuum advance only. They used a combination of ported vacuum and venturi vacuum to get the right advance curve for all RPM and load combinations.

I didn't know that. Thanks. Sounds a little complex, but it certainly would work.

[Art Newland]

I think mike657894's dream of throwing a vacuum module on a Model A to replace the spark advance lever is the question, the answer in no. Maybe you could take the principle of Ford's all vacuum setup and apply it to a model A, but it wouldn't be easy or cheap or work as good as an all mechanical advance setup. Mechanical advance with direct manifold vacuum advance is the hot "low-tech" setup.

[C26Pinelake]

from a non mechanic how would this improve the performance of a stock engine and why would you do it ? Wayne

[BRENT in 10-uh-C]

Originally Posted by mike657894

I had an idea to mount a vac canister from another distributor to the stock A distributor. Maybe with a bracket. Will it have enough oomph? Can I get one with enough stroke? Is there a reason it would just not work no matter what? just seems like it could be a 20$+time upgrade and one less thing for people to learn that I teach how to drive the car . Has anyone here done this and succeeded or failed?

Mike, in my line of work, -AND being an avid Model-T hobbyist also, I have trained more than just a few people on how to properly operate both a Model-A and a T. While I applaud you for 'looking out' for a rookie in training, I feel you are also doing them a disservice simply because they are learning to drive YOUR car, ...and not the typical Model-A.

The Model-A Instruction Book that was provided with each new Ford vehicle (--and also available in reprint) devotes about 6-8 pages to the steps one needs to follow in the proper operation of a Model-A. Might I suggest you make a check-list similar in design to a checklist that is used during a pre-flight/post-flight inspection of an airplane that allows your student to go thru and learn the correct/approved procedures for operating a Model-A.

[Y-Blockhead]

Originally Posted by 40 Deluxe

It CAN be made to work! Ford did it from 1949 thru '56. Vacuum advance only. They used a combination of ported vacuum and venturi vacuum to get the right advance curve for all RPM and load combinations.

Called the Load-o-matic by Ford. You would need a carburetor the has both ported and venturi vacuum ports. On cars that were equiped with the setup had 'matched' carb and distributors.

Most guys with Y-Blocks switch to the '57 up distributor (mechanical and vacuum advance) and carburetor to match for ease of setup and better performance. The Load-o-matic may be made to work on a Model A but why bother?

On of the things I like about driving a Model A is you get to "fiddle" with things and impress your unknowing passengers...

[mike657894]

thank you for the knowledgeable answers I thought it might be as easy as make the bracket. Im not trying to spend much if any money. I will have to get an instruction book and put it in the car for any future drivers. I could have used it when I started.

[Willie Krash]

The spark lever is what makes the car fun to drive. Learn a skill set that others cannot image, like a stick shift.

[KGBnut]

I'm one of those guys that likes all the things in the Model A that are not automatic. In my mind, it's part of the fun. However, IF I did want to simplify (and damage-proof) my car for novices, I might look into the Sparky-Start. It may accomplish what you are trying to do, which is protect your starter. At one point, I was thinking about getting a Roadster for my wife, and a Sparky-Start was one of the things I was considering for her.

Also, if I'm not mistaken, it is a period correct accessory.

Click here to see the Sparky-Start at Bratton's.

Ken

[pgerhardt]

The problem is that most (I would guess) do NOT adjust the spark while driving. At best it is "up to start" and then "down to drive". Of those who do attempt to adjust the spark, how many do it correctly?

[Special Coupe Frank]

If you want "automatic spark advance", I would go for either the centrifugal weight unit that replaces the stock distributor drive shaft, or a modern distributor conversion.

Adapting a vacuum control to the stock distributor needs to be carefully engineered, so that it works correctly, and does not do more harm than good.

If I were heading down such a rabbit hole, I would plan on using an external-link vacuum chamber, such as Chevy used on their Stovebolt Sixes, where the vacuum control rotated the entire distributor body; the bracket and link would be better engineered to work with the stock breaker-plate arm.

Then, you need to figure-out the vacuum connection... all distributor vacuum controls that I am familiar with, have their vacuum connection at the throttle body. The vacuum port, and where it is located in relation to the edge of the throttle plate is critical.

The last big element is that most vacuum controlled distributors ( mid-Century Ford products excepted ) also have a centrifugal advance. The vacuum "advance" is actually a vacuum modifier that reduces spark knock on a hard pull. It's actually a vacuum "retard", in most cases, taking the edge off the advance that the mechanical advance is creating
( Reduced vacuum in the chamber, allows the spring to push the diaphragm & link towards "retard" ). When the load eases and vacuum improves, the vacuum is able to overcome the spring pressure in the device, and advances the spark again.

So, the device really should be called a "loss of vacuum retard", rather than a "vacuum advance". And it is part of a system that includes the centrifugal advance system inside the distributor.

Perhaps the best term is "automatic spark control".

It's complicated, and simple, at the same time.

( I have to plead unfamiliarity with Ford's "vacuum-brake" distributors on the flatty V-8 and six, and their later "balanced" distributors. )

[CT Jack]

I have an FS Ignitions mechanical advance distributor with an electronic ignition module. This distributor is approximately 1/2" taller than a stock A distributor but looks identical. They call it the "Zipper". It works perfect and makes driving an "A" a real joy. I can start the engine, go up hills, and accelerate without touching anything. The advance and retard lever is locked. Installation is simple.

[Special Coupe Frank]

Originally Posted by pgerhardt

The problem is that most (I would guess) do NOT adjust the spark while driving. At best it is "up to start" and then "down to drive". Of those who do attempt to adjust the spark, how many do it correctly?

IF the timing is set-up correctly in the first place, you could do the following:

UP for starting

Middle for idling and around-town driving (below 40 mph), or pulling long hills.

DOWN for high-speed driving (40 MPH and up )


This has been my "system". Generally, I do not constantly fiddle with the spark. If I'm in stop & go, around-town traffic, I'll set it at 1/3 to 1/2 down and leave it.

Out on the open road, I'll pull the lever all the way down.

[Dick Steinkamp]

Originally Posted by Special Coupe Frank

The vacuum "advance" is actually a vacuum modifier that reduces spark knock on a hard pull. It's actually a vacuum "retard", in most cases, taking the edge off the advance that the mechanical advance is creating

Frank,
I think you may have it backwards. Here is a good explanation (2nd post)...

http://www.chevytalk.org/fusionbb/sh...hp?tid/239321/

Another (scroll down to "vacuum timing advance")...

https://en.wikipedia.org/wiki/Ignition_timing