Vacuum advance.

[strutgka]

Hi..!

Someone here in the forum who can respond to what the difference between the vacuum advance with part b9af-12370-b and B7a-12370-a is.
I have a -57 distributor and it's equipped with a b9af-12370-b, but this seems impossible to get hold of, so a thought popped up if this can be replaced with a B7a-12370-a since they at least look identical, and this is easier to buy. Is this possible..?

Thanks in advance..//Karl-Johan

 

[dmsfrr]

I'll start off by saying that I'm not 100% certain if one advance canister unit fits, works better or is different than the other.
But.... 1957 was the first year of a significant change in the way Ford made their distributors.
I suspect there were few options of advance canisters for '57 and the one that is easier for you to find & buy may actually be the 'more correct' one to have.

In the part number prefixes 'b9af' and 'B7a', the letter 'B' indicates the 50's decade and the second digit, 9 or 7, indicates the model year the part was first created for, '59 and '57.
The distributor design was changed slightly in '59.
If the actuator arm into the distributor is straight or curved, it makes a difference.
For '57 it would most likely be straight.

I'm guessing the 'B7a' part may be the right one for your '57 distributor.
.

 

[strutgka]

dmsffr...!

Thank you very much for the information. What you describe, I knew nothing about.
As I see it, it should in this case be no problem to mount a B7a advance canister just like you wrote. The one I have today is with a straight arm (see picture) and this ought to be the crux then I think that the bracket is the same to the distributor for the Y blocks.
Thanks again ..// Karl-Johan