Does your current unit have wights and springs under the breaker plate?If it does than it is at least a 57 distributor which means if you disable the vacuum advance(why I dont know)the car will still run off idle but not well until you have enough RPM for the centrifugal to kick in.I am still unclear as to what you are trying to accomplish with this idea.On the side of distributor housing there is a number stamped into it part of which is 12127 with numbers and letters before and after.If you post those #s someone can ID the distributor origin. 

  

Crazy aint it?

55Birdman  Hickory NC

I believe that the 55 Bird tach drive dizzys had only a single vacuum can. The best way I know how to tell the distributors apart is the inside. The 56 and 55 ones had a spring located topside of the point plate. 57's did not.. Cap size is also different, but without then side by side you may not be able to tell the difference.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Mine is 1 1/2" deep bowl. But I pulled cap and vacuum arm is straight as Mummert says but the model #s are no where near what he says. Mine say Niehoff & Cp Model FF17E. Never heard of it. After market maybe? I have had this car a long time with this distributor in it. I am not sure. Thanks for the input

55Birdman  Hickory NC

Birdman:

The bowl part of a '54-'56 distributor is about 1" deep.  The '57 and later are closer to 1 1/2" deep.  The cap diameter is smaller on the early one, but I don't have the numbers in front of me.  If you need them, let me know, I'll measure them.

John in Selma, IN

John - "The Hoosier Hurricane"

Thanks for the info. I looked on mummerts site and found that the vacuum advance arm is straight on the 57. but the serial number isnt the same as listed. Mine is model FF17E. which is in no way what mummert has. But I do have shims and all the other visuals he describes as 57. so I will go with the assumption that mine is 57. Thanks for the info .

55Birdman  Hickory NC

If your distributor has tach drive - and doesn't have a "dual advance" vacuum pot hanging on there ------- meaning the one with the two piggyback cans and two ports for the old teapot carb -----it would likely be from a 57. I believe a 55 or 56 tach drive would have the double can.

I think the 57's had a "ball bearing" point plate pivot too. 

The "single advance" style vacuum pot (57 and later) will have a hex nut on the nose (where the vacuum port enters). If you dismantle this nut- there are shims under there to preload the spring and change the rate of vacuum advance per inch of Hg. If you put in a lot of initial advance (12°-14°) at idle - and don't limit the total centrifugal - it is possible to mechanically "over advance" the spark at elevated revs. Even if you limit it (36°-38° would be a good maximum) the vacuum pot might add enough at cruise to cause a knock. So ----- adding shims to the vacuum pot is a way to cut back on how much advance it can add on to the total at elevated vacuum.

 
 Steve Metzger       Tucson, Arizona

mine has a tach drive. How do I know what year it is? Any ID or anything. maybe it is a 57 

55Birdman  Hickory NC

Birdman:

If this distributor is for a Bird, the ones mentioned above will not have the tach drive.  '57 T-Birds were the only ones with factory tach drive and mechanical advance.

John in Selma, IN

John - "The Hoosier Hurricane"

The petronix I installed was for a 57. I had to do a little mod on it to get it to install. been working fine for about 8 years.

55Birdman  Hickory NC