Vacuum advance unit connections

[WOO5IE]

Hi, Answer is probably on here somewhere but there is a lot of info on timing / vacuum advance but this is just a simple question as I don't seem able to find the answer.
I have just replaced the vacuum advance unit on my 4.00 Chim . It has 2 connections one being the tube to the manifold . It is still ported and the other connection on the original is blanked off by a small rubber tube with a bolt in. This is on the other side of the diaphragm . It has always been on the original . so question is do I need it and why is it blanked off. Should I blank this of on the new unit.
Was this factory blanked as I have had the car for over 12 years

Thanks

Trevor

Edited by WOO5IE on Monday 4th November 17:14

[J-2]

Does this help, fitted by X Work last year. If this is the way they do it it must be right.

[WOO5IE]

Thanks, that exactly the answer. I don’t why and what would happen it it wasn’t blanked.

👍

[lancepar]

WOO5IE said:

Thanks, that exactly the answer. I don’t why and what would happen it it wasn’t blanked.

??

It could be left off but looks better with it capped,.

This is how I see it.



The diaphragm at rest has equal pressure either side, so when suck from the plenum is applied and because the inside if the dizzy is not air tight it responds and alters the spark point, so capped or not will still work.

[Paulprior]

Does anyone find that it makes any difference?, I replaced a faulty unit and didn’t notice any change ??

[lancepar]

When I changed my faulty one I tested it by sucking on the tube, easy tiger, and with the dizzy cap off could see the base plate moving.

No change noticed in the running either but it is intended to aid economy/mpg.