Distributor question

[Mach1JB]

Guys,

As my buddy helped me a lot to restore my 72 351CJ he asked my a question today about his 351W engine in his 78 Ranchero.

Car is running bad and i already found out that the vacuum advance on his distributor is leaking. ( he also needs a new 2bbl car but thats a different story )

So he needs a new vacuum advance unit.

I searched the internet for an hour or so but can't figure out if his distributor is a single or double advance type !??

The following casting numbers are present on the distributor.

D8AE 12127 JA

So i already know that this is a distributor for a 78 Full size car, but has it single or double advance , is there a simple way to see that !?

Thanks in advance ( LOL )

JB

 

[73 MACH 1 MAN]

If I remember correctly a double advance will have 2 vacuum lines going to it. 1 for advancing and 1 for retarding. I think the dual was for emissions!

 

[Totalled]

Single advance = 1 vacuum nipple. Dual would have two, one out the front, one out the top.

 

[will e]

I believe the double advance is set up so it can use either ported or manifold vacuum. There is typically some type of control for this (they are not just connected right to ported/manifold)

 

[c9zx]

I believe he is asking if it is supposed to have a single or dual diaphragm advance. Finding this data is not as easy as you'd think it should be. I'm currently looking for original source reference books. This is not a definitive answer but may help. http://www.oreillyauto.com/site/c/detail/ACD0/F1355/01973.oap?year=1978&make=Mercury&model=Grand%2BMarquis&vi=1199189&ck=Search_01973_1199189_-1&pt=01973&ppt=C0039

EDIT: I don't know why when the link opens it will not show the detailed information. However, it does list the distributor number you have. I got there by doing a Google search on the part number and selected the O'Reilly's citation.

Chuck

 

[Mach1JB]

Any pictures from a dual ??

 

[73 MACH 1 MAN]

 

[c9zx]

Should look like this. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=NRD482875_0271593978

The wide crimp band stopped after 1971 as near as I can determine. Chuck

 

[Mach1JB]

Thanks Guys ,

I just ordered the right vacuum advance.

JB