Vacuum Advance Units - twin connection vs single

[T25Convert]

Hi,

The vacuum advance on my 1.9 DG dizzy is knackered (you can suck through the vacuum line with no effect!). Its the single connection advanec only type.

I have an old T25 dizzy with the twin connection vacuuum advance and retard unit on (came with some other bits I bought).

It physically fits, but will it do the same job as a vaccuum advance only unit if the retard pipe is not connected?

Looking for a short term fix!

Cheers,

Alex

[CovKid]

You can soon tell. Screw it on, stick a short pipe on, suck on the pipe and see if plate in dizzy moves. Stick your tongue over the end on full suck to see if plate stays there. With suction released, the plate should snap back to where it was. If it checks out - yes. Simple as that.

[bigherb]

In short no unless you know the engine it came off. The vacuum units are matched (actually it's the spring inside) to the carb and timing characteristics different carbs have different amounts of vacuum.

[CovKid]

carbs??

I have to disagree - to some extent. I've fitted a couple of double vacuums to single vac dizzies and merely checked and reset timing afterwards. Its not ideal but they can be used - depends which one/type. The prob really is how long the arm on the vac unit is (several types emerged over the years). If its way off the single unit then definately no.

[T25Convert]

Covkid,

I've fitted it and it seems to do the trick, in so much as it advances fine, and seems to retract back again as well.

Will check if it advances enough once I've sorted an issue with the carb to get it running to time it!

Cheers for the assistance,

Alex

[jamesandtheopenroad]

You can get a new single vac from here. About 20quid.

http://www.simonbbc.com/ignition-spares ... vance-unit" onclick="window.open(this.href);return false;

[trickyrichb]

Jamesandtheopenroad,

Have you fitted one of the units you supplied the link to? My 1.9dg is in need of a replacement vac unit.

Thanks

trickyrichb

[jamesandtheopenroad]

Yup. Mine wasn't too bad but wasn't going to get any better.

Took the dizzy apart for a clean up when I did it and lubricated the advance springs too. Miles better now.

Easy to do the change of vac unit. 10 mins maybe.

[T25Convert]

Cheers for the link - I see how the one I've got on performs, any doubts I'll get a new one. Far cheaper than any other suplier I've seen too which is a bonus!

Cheers,

Alex