How do you test if the vac unit on the dizzy is working?

[big lad]

As the title , how do you check its working ok, i have accuspark electronic ignition
cheers in advance

Tony

[wilf]

If you have a strobe, then at tick over you should be able to see if it is working by simply pulling the vac line off the dizzy? You should see the timing change (retard) as you do that.

If you have (really) strong lungs you could also try sucking on the pipe to the dizzy to see if that changes the timing, too. I cheat with a vacuum pump.

[72BLUE]

Hi Tony, I think the general consensus is that you 'suck' on the tube connected to it. This should easily move the baseplate if the vac units membrane is still intact and working properly. There will be more scientific ways to measure its actual performance against spec by, for example, using one of those hand held vacuum jobbies that most folks don't have.

I believe that the current cheap vac units for sale, unless things have changed recently, are made in China and are not to correct spec because they have too thick a membrane in them.

For this reason, unless some expert can put me right, I would be wary of buying a new one. The exception being if you buy from one of the folks that reconditions/rebuilds them to correct spec. I replaced my dead vac unit with a recon one from http://www.distributordoctor.com/ - not cheap, but a proper job from a recognised expert. He does recon distributors too I believe, again here, other people offer new dizzy units complete with new vac unit, but you need to make sure that everything is to the correct spec by asking some awkward questions before you part with your hard-earned.

Cheers
Keith.

[big lad]

Thanks guys, will have a fiddle this weekend

tony

[dasadrew]

Damn! I was too late to post "Suck it and see"