18 replies to this topic

[Big_Adam]

Yo once more dear friends.

Taken my dizzy apart and cleaned it up (it's silver, who knew!) and wanted to know is there any part that should be replaced before I put it back togther?

I know there's not alot to it but thought I'd check. It's from a 998, it's a lucas one. Thats about the most I know, vac advanced too.

Ta.

[Jupitus]

Main thing to check is the amount of play in the shaft - if there isn't too much sideways slack it ought to be ok.

Make sure the mechanical advance weights etc aren't seixed while you are at it

[Mephiston]

might as well do the points and condenser while its nice and accessible (unless you already have)

[dklawson]

As Jupitus said, the big wear area is/are the bushings. Also as he said, make sure the bob weights are free. Check the general condition of the springs. (They're NLA by the way... so don't loose them. A limited spring assortment, not specific to any car, is available from Cambridge MotorSport).

Make sure the ground wire between the breaker plate and dizzy housing is there and in good condition. Make sure the vacuum advance unit is working (both the condition of its diaphragm and the adjuster nut free to move/turn). It should go without saying that you do as Mephiston suggested and fit new points and condenser. However, don't overlook fitting a new cap and rotor at the same time.

[Big_Adam]

Pictures are worth 1000 words they say so:







I'll check for play when I put it back together. No adjuster on the vac advance but it dose seem a little stuff. they cost £20 a pop though I'd rather not get a new one but if I have to then I have to.

On a similar note.



I know where the roll pin goes, and that weird bit but what about the washer with the tab.

[Gibbon]

As Jupitus said, the big wear area is/are the bushings. Also as he said, make sure the bob weights are free. Check the general condition of the springs. (They're NLA by the way... so don't loose them. A limited spring assortment, not specific to any car, is available from Cambridge MotorSport).

Make sure the ground wire between the breaker plate and dizzy housing is there and in good condition. Make sure the vacuum advance unit is working (both the condition of its diaphragm and the adjuster nut free to move/turn). It should go without saying that you do as Mephiston suggested and fit new points and condenser. However, don't overlook fitting a new cap and rotor at the same time.

Sorry to hi-jack your thread Adam!
Just wondering how you check if the vac unit works and if the bob weights are free ?????


Could someone extrapolate ?

[Big_Adam]

The vac unit (if you want tech) move to "X" amount of atmospheres of mercury. Which is stamped on the vac unit.

But to test I just suck on the damn thing and see if it moves. Think my one after it's swim in the white spirit has bugged it. As for the weights I just gave it a spin by hand to see if they moved out. Then tugged them with my finger to see if they stuck or had any grit on them.

Thats about it really. Not sure if it's the right way to do it tho,

[dklawson]

The vacuum advance capsule is typically tested by simply sucking on it as Big_Adam said. What you're looking for is an air leak that would prevent it from moving. There aren't repair kits for these so they either work or don't.

The best way to check the bob weights is to remove the advance/breaker plate from the dizzy and move the weights by hand using a screwdriver. Anytime you take the time to do that, put a drop of oil on the weight pivots. The most common problem is the pivots run dry and they rust to the weights.

[Gibbon]

Thanks for that chaps.

I also have 2-3mm play in the rotor arm. Is that bad karma ?

[Big_Adam]

Try a new arm. Only cost £2 or less.

edit

You do mean the plasitic arm at the top of the dizzy shaft right?

Edited by Big_Adam, 17 August 2007 - 08:41 PM.

[Gibbon]

Try a new arm. Only cost £2 or less.

edit

You do mean the plasitic arm at the top of the dizzy shaft right?

Sorry, when I say rotor arm I meant the shafty bit.
The dizzy shaft has a couple of mm play left and right

[Big_Adam]

Ooow....I think thats alot.

[dklawson]

Stop. Describe how you observe the 2-3mm of motion in the rotor.

IF you are holding the distributor and TWISTING the rotor, look and see if the four lobe cam below the rotor is moving in sync with the rotor. If it is, that's normal, that's what your centrifugal advance does. If the play is side-to-side and the four lobe cam is moving with the rotor... get a replacement dizzy. IF you are pulling the rotor up and pushing it down to get the 2-3mm, remove the rotor and make sure the Philips head screw under the rotor is secure. If you're twisting the rotor and the four lobe cam is not not moving, then replace the rotor as this indicates play between the rotor and the spindle shaft.

[Gibbon]

Stop. Describe how you observe the 2-3mm of motion in the rotor.

IF you are holding the distributor and TWISTING the rotor, look and see if the four lobe cam below the rotor is moving in sync with the rotor. If it is, that's normal, that's what your centrifugal advance does. If the play is side-to-side and the four lobe cam is moving with the rotor... get a replacement dizzy. IF you are pulling the rotor up and pushing it down to get the 2-3mm, remove the rotor and make sure the Philips head screw under the rotor is secure. If you're twisting the rotor and the four lobe cam is not not moving, then replace the rotor as this indicates play between the rotor and the spindle shaft.

Ouf, sounds like it's OK then !
When twisting, the rotor moves in sync with the spindle shaft - On closer inspection i'd reduce the "play" (advance, now that I know!) to 1mm either way

No sideways play. Minimal up-and-down play.


Oh .... just had a suck on the vac unit and got a gobfull of nice petroly tasting air. So that's shafted then !
Merde !

[dklawson]

Put a piece of tubing on the connection to the vacuum advance. Suck on the tube to pull in the advance unit (watch the breaker plate). Pinch the tubing off or cap it with your thumb. Watch the breaker plate in the dizzy. If it stays advanced, the vacuum unit is OK. If if falls immediately back to its rest position, the vacuum unit is shot. If it drifts back slowly, you have a small air leak. Small leaks won't affect your car very much and you can probably use the distributor a bit longer until the vacuum unit has a complete failure. A complete failure won't be catastrophic, the car will still run. However, the idle speed may become erratic and your fuel economy may drop off a bit on highway drives.