How to set points vacuum advance cam in distributor

leregulage

leregulage

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On a ducellier distributor(working on a 404 sedan here-but applies to all makes with the same setup). When a new set of points are installed, should they line up perfectly- with the engine off?

This has a vacuum advance-with that turnable cam/ against the rod of the advance cam. I'm thinking to just give it a few notches, until they line up straight.

Am I wrong on this?
 
Seems the new points are a bit longer or shorter than the ones it came with( this is a china copy dizzy for a 504- can be found on ebay for very little).
 
That turntable thingie is there to compensate for low octane petrol, which may cause pinging. Your points should be set so you get a spark at TDC (static), then timing light with vacuum disconnected, then connect the vacuum and drive and only then use the cam if you hear any suspect noises.
 
One half of the points is stationary, and the other moves in and out against it. However the movable one also moves back and forth, rubbing against the fixed one powered by the vacuum. This is how they are self-cleaning.
Therefore the movable one starts at one end and is sucked towards the other end by the vacuum advance.

Then eventually....after some time.... an oblong-shaped depression is created in the fixed point.
So you should set it so that the circle of the movable point is completely within the circle of the fixed point, but to one extreme.....giving it some room to move.

Never push on the rod going to the vacuum diaphragm....you can rupture the diaphragm that way. Only ever suck on the tube to test how far across the points move.
 
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Beano is spot on, they deliberately don't line up. On points without this system, you get that little pointy bit deposited on one contact.
 
Beano said:
One half of the points is stationary, and the other moves in and out against it. However the movable one also moves back and forth, rubbing against the fixed one powered by the vacuum. This is how they are self-cleaning.
Therefore the movable one starts at one end and moves towards the other end, eventually....after some time.... creating an oblong-shaped depression in the fixed point.
So you should set it so that the circle of the movable point is completely within the circle of the fixed point, but to one extreme.....giving it some room to move.

Never push on the rod going to the vacuum diaphragm....you can rupture the diaphragm that way. Only ever suck on the tube to test how far across the points move.
Click to expand...

Thanks for that, it is exactly what I'm looking for.
 
Good to know I made a difference to someone's life.:)

If the car ever runs rough because the points have got clagged up, naturally the first suspect is the vacuum advance. To test, just take off the distributor cap, unplug the vacuum tube from the inlet manifold and and suck on it. The movable point will move.
Vacuum advances aren't getting any younger.

I'd recommend an electronic distributor....it was such a relief when I fitted one to my 504. Bloody points cause the timing to go out slowly but surely, though the Ducellier are by far the best distributors.

But the advance curve may be different if you get one from a 505. You could always get one of those aftermarket ones you fit to the existing dizzie......
 
Yeah, my vaccum capsule required replacement on my R12 and I just a few weeks ago rebuilt a Mitsubishi Triton carb which also needed a new one. It makes a big difference too.
 
Haven't checked the dwell, it runs fine for now. This 404 came with a non- vac distributor, so the china copy one is quite the improvement. I'll be going to electronic ignition soon. I use one off Ebay(accuspark/hotspark), they seem to do a good job. Used a few of their modules through the years.

Really hard to find good 505 electric dizzys over here. So the aftermarket is a close second.

https://www.ebay.com/itm/Electronic...:sc:USPSFirstClass!22644!US!-1&frcectupt=true
 
That is exactly the same kit as I purchased from the UK.
 
Artificer,
Have had one of these fitted to my 504 for about 3 years now. Perfect starting hot and cold. Instantaneous starts from dead cold or if standing for a day or more.
Have misplaced the UK address of supplier, anyone ?
 
Some mis-info on this thread about point burning & deposits from one point to the other. This is generally caused by incorrect condenser.
UK source but there is also an eBay source in OZ.
https://simonbbc.com/
 
My preferred method for setting timing with points ignition is this:

1. Assuming new points, set gap with feeler gauges etc.
2. Set engine at idle advance point. eg 10 deg BTDC.
3. Connect a multimeter between points and earth.
4. Loosen distributor and rotate until the points just open. ie no connectivity. Fine tune several times, until you're sure you have that exact sweet spot.

This method is very accurate and most useful when the engine is out of the car etc. and you want it to fire first turn.
 
PeterT said:
My preferred method for setting timing with points ignition is this:

1. Assuming new points, set gap with feeler gauges etc.
2. Set engine at idle advance point. eg 10 deg BTDC.
3. Connect a multimeter between points and earth.
4. Loosen distributor and rotate until the points just open. ie no connectivity. Fine tune several times, until you're sure you have that exact sweet spot.

This method is very accurate and most useful when the engine is out of the car etc. and you want it to fire first turn.
Click to expand...

That is the method I use when I have built a fresh engine. It has never failed.
 
Artificer said:
Some mis-info on this thread about point burning & deposits from one point to the other. This is generally caused by incorrect condenser.
Click to expand...

True...usually condensor.... but I was only saying that if the vacuum advance is not working properly, that will also stuff up the points.
 
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My understanding is that with a good condenser it just happens more slowly. Unless those new condensers I bought for my Cooper S back in the day were shite.
 
Method used to set timing.
Locate timing mark on pulley. Loosen distributor. Car radio on, slightly off channel. Volume up. Ign on, now rotate dist* until static "click" is heard.
*Rotate dist until it aligns with timing mark. Whew !
 
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