Slant six distributor vacuum advance unit

[French demon]

Hello buddies

Today, I converted with success my distributor to Pertronix electronic module. The engine starts
During the conversion, before mounting the Pertronix module, I tried to control and move manually the vaccum advance arm which is inside the distributor = very hard to move, even with the points plate removed.
I tried to aspirate through the vaccum unit = no move

Is the vaccum unit out of service? Or is it normal to be so hard to actuate?


François

 

[Darter6]

Remove the vacuum unit and the plate to expose the mechanical advance weights.
I would say they are stuck. Lube them with a penetrate oil and get them moving freely.
Also check for the weight springs that they are in place. With the vacuum canister removed apply a vacuum source and see if it moves free and holds vacuum.

 

[French demon]

Hello Darter
I forgot to say that I checked the weights. They move freely and the springs are there. I also lubricated them.
I will try to disassemble once again the distributor to check the vacuum canister.
It seemed strange to me that it's so hard to actuate.

 

[67Dart273]

I would say hard to move is normal. You need a vacuum source/ vacuum gauge, or one of those little hand pumps, similar to this

Like in the photo, this is a brake bleeder kit, but same pump

https://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-63391.html?utm_source=google&utm_medium=cpc&utm_campaign=21901271210&campaignid=21901271210&utm_content=171677806502&adsetid=171677806502&product=63391&store=457&gad_source=1&gad_campaignid=21901271210

 

[Bewy]

The VA unit should move if you suck on the nipple. It may only move a small distance, but that would indicate it is working.
In your pic, it looks like a threaded rod goes into the lower plate. That would STOP VA movement because for VA to work, the upper plate slides over the lower plate....

 

[French demon]

The VA unit should move if you suck on the nipple. It may only move a small distance, but that would indicate it is working.
In your pic, it looks like a threaded rod goes into the lower plate. That would STOP VA movement because for VA to work, the upper plate slides over the lower plate....

Hi Bewy.
Don't care about the screw that goes through the points plate. it was an ex-owner arrangement to hold the points. I've removed it before installing the Pertronix module

Thanks to 67Dart273, I remembered that I've this kind of tool (I'm so stupid sometimes )

When pumping, the dial hand rotates to the left, stops and doesn't move anymore.
When I release the vacuum, I hear a little "click" from inside the distributor, and the hand comes back to 0.

Bewy : with the cap off, and repeating the test above, I can see the plate moving a - very - small distance (about one or two millimeters only)
Video :

If you confirm that this tiny movement of the plate is correct, my vacuum diaphragm works well

all

François

 

[Bewy]

The factory spring inside the VA unit is quite strong. When you are 'sucking', you are sucking against that spring, so what you are getting sounds normal. With the VA unit, push on the actuator to make sure it bottoms out against the stop freely. Then good to go. Bon soir.

 

[halifaxhops]

Sounds like it is bad. It should move the amount of advance that is stamped om the arm. I will have them at Carlisle. Still have some unpacked if needed.

 

[French demon]

I didn't notice anything stamped on the arm. Maybe underneath?

 

[RustyRatRod]

Hi Bewy.
Don't care about the screw that goes through the points plate. it was an ex-owner arrangement to hold the points. I've removed it before installing the Pertronix module

Thanks to 67Dart273, I remembered that I've this kind of tool (I'm so stupid sometimes )
View attachment 1716414354
When pumping, the dial hand rotates to the left, stops and doesn't move anymore.
When I release the vacuum, I hear a little "click" from inside the distributor, and the hand comes back to 0.

Bewy : with the cap off, and repeating the test above, I can see the plate moving a - very - small distance (about one or two millimeters only)
Video :

If you confirm that this tiny movement of the plate is correct, my vacuum diaphragm works well

all

François

That looks about right. Keep in mind when looking at the distributor, you're looking at half crankshaft degrees. In other words, if you see about 10 degrees of movement on the distributor plate, that equals about 20 crankshaft degrees.