The V8 Owners Forum -

Hi Folks,
Anyone know how to set the vacuum advance on these and change the springs?

Did not want to start undoing things until I knew what I was doing in case there is some special alignment I might cock-up

When I suck on the vac port the base does not seem to move..should it? It seems quite stiff when I move by hand so I wanted to check the springs and see if anything is seized up. Should I be able to move it by sucking or is the engine vacuum much stronger?

Any thoughts?

What carb are you using? (assuming that you are using a carb). The Edelbrock carb has two ports, one is upstream of the butterflies and will only have vacuum once the butterflies start to open.

I use large (100 - 200 ml) medical syringes without the needle for testing vacuum related things.

like this:
http://www.ebay.co.uk/itm/Reusable-100M ... SwT6pV3BUR

sidecar wrote:What carb are you using? (assuming that you are using a carb). The Edelbrock carb has two ports, one is upstream of the butterflies and will only have vacuum once the butterflies start to open.

It's an Eddy. Yes I've figured out the port to use but more wondering how I get to the springs in the mallory dizzy. I can't find any resource on this online.

Eliot - given your suggestion for the syringe does that mean it is not normally possible to suck in the vac pipe to get the thing to move?

I dunno about the Mallory one, but you can see a Lucas one move by sucking with your mouth. But you may need to used a hose etc your lips can seal round easily.

FWIW, I did have a Unilite for a while. But never did find a clear guide on how to set up the advance curve. Luckily, programmable ignition is cheap enough these days to make it a bit academic.

Hi Dave, when you say 'cheap enough' what does it cost and what's involved to replace?

Given that Mallory bits are getting harder to come by I will need a plan b at some point.

I've got a custom curved Scorcher dissy in mine that uses a machined Ford body and all easy to get Bosch internal parts, rotor and cap. Vac advance runs off the always on vacuum port on the Eddy, gives smoother idle, better cooling. Advance at idle is set at 10 degrees and it's all in at around 28 on the 4.6.

moppit wrote:Hi Dave, when you say 'cheap enough' what does it cost and what's involved to replace?

Given that Mallory bits are getting harder to come by I will need a plan b at some point.

It rather depends on how good you are at finding bargains. The simplest would probably be MegaJolt controlling EDIS. Or any MegaSquirt with a V3 PCB onwards. Which will need coil drivers added.

Buying used carefully, you could probably do it for well under £300. New prices you can look up. But the ability to dial in any advance curve you want from your laptop etc is beyond price.