So, I was intending on replacing the elderly vacuum advance unit as PM. Ordered a new non-OEM part from Welsh Ent. In US.
Part arrived and the profile of the base is different. My one has a squared off profile, vs. Curved on replacement part. The profile where it slots into the distributor seems the same, however, it would no longer seal properly (assuming mine has a seal at the base and it's not dirt!).

I contacted Welsh Ent. And they looked into it. Seems that is the only design they have ever sold, plus similar to ones from other parts suppliers.

Can anyone kindly shed any light on this?

Quentin

 

I have on my web site library a list & picture of vacuum units, might help narrow it down>>> https://www.jaguar-wiring-schematics...%20vacuums.htm
is there a problem with the old one? have you tested it with a hand pump with vacuum gauge?

 

It should fit. Gently drive the roll pin that's holding it in place out and you'll find that the old one has that same profile.

 

Wow that's detailed!
However, none seem to have the same squared off base as mine.
To my knowledge it's working fine. Just had the Vee cleared out so figured I would replace as it looks ancient.

 

Agreed, however mine has what looks like a seal in tbe squared off section. Seems doubtful the seal would work with the new one?

 

In this link it appears that the author had the same scenario as me and it would appear the different style replacement works. Indicates mine is 35yo!

 

Confirmed it will fit and the answer was already here

https://www.jaguarforums.com/forum/x...nt-v12-242957/

 

That should fit your Lucas dizzy. It's the same as Barratt ones. All made in China. And without the pointless adjuster on the vac.

 

Yes it fitted fine. Kerfuffle over nothing.