I finally got around to testing my Vacuum Advance with one of those Brake Bleeder/Vacuum testers. The larger port holds no vacuum and does not move the actuator, the smaller vacuum port holds a vacuum but for a very short time. I assume that this is part of the problem I'm having with acceleration/ deceleration both of which are not all together smooth.

Am I going about testing this correctly? Can I do anything to help other then purchasing a working vacuum advance? Where can I source one of these vacuum boxes?

Thanks,
Dan

Is this a 1.8L L-Jet ?

75 2.0L D-JET

Are these unit interchangeable with a VW brand such as this item:

http://www.aircooled.net/new-bin/viewprodu...IGD0007&cartid=

No retard function on that one!

They have them both ways.."adv & retard" and " adv only". Seems about $50 or so cheaper than the porsche one.

Does anyone know if it will work? Are these standard or are they calibrated for the particular application?

I emailed the tech support at Aircooled.NET and will let you know what they say.

Just got back a reply and they stated it will work.

It will work, BUT, the total retard may be different and the advance curve will be wrong. There MAY also be fitment problems, depending where the screw holes are on your distributor. However, the correct part is NLA, so it's the next best thing. The Cap'n

Cap'n just wondering about your experience with this particular unit, is it a certainty that the total retard and advance will be wrong?


Thank you,
Dan

I purchased one, I should get it later in the week. I will take some rough measurements on the advance and see how it compares.

Anyone have any measurements on the retard, e.g. how much vacuum versus the throw on the rod?

The factory manual has graphs for how much vacuum versus how many degrees of advance or retard. You can see a collected table of those measurements here:
http://web.archive.org/web/20000414125755/...ch/distrib.html

--DD

That's great thank you.

I got the new unit and it looked as though it was going to work; the advance seem to be about the same, when placed under vacuum the rod moved in approx. 2mm on both units.

Unfortunately the advance port is on the bottom of the pot and obstructs the distributor from being timed. I guess I will have to flip the bill for a new one unless some one has a working used one for sale?

Hope you have better luck than me.

My 75 2.0 vacuum RETARD canister is toast. No advance on mine. Haven't been able to find a part yet.

NLA for at least 10 years. Make it work. The vac ports are a long way from the clamping bolt IF the distributor is installed properly. Never seen one any other way. The Cap'n

The vacuum advance port is hitting up against the oil filler/breather, not sure how to get around it. The vacuum pot points to the drivers side.

Any suggestions?

I have attached a couple of pictures to depict the problme. Any suggestions on what I should do?

(a) cut the tube and slip on a rubber angle (If I can find one)
( heat the tube and bend it, I'm afraid to damage the diaphragm
© Use the original vacuum advance unit and forget about the retard portion (what does this do anyway?)

Dan

Picture 2

Can you INTENTIONALLY reposition the distributor 90 degrees off and make it fit? Then you could rotate your wires one position in the cap to make up for it. It'd have to be moved either 90 degrees or -90 degrees.

May be a dumb idea. I'm too lazy to go out and look at mine...

Jim

Maybe there's another configuration I don't know about, but in my understanding...

If we're still talking about the '75 2.0, there should not be vacuum advance. Vacuum retard is necessary to have a correct timing curve and retard the timing at idle. The tap that is bumping into the oil filler bail in your photo is the advance tap. Not used. Seems to me it could be cut off. But maybe someone else will tell us why it's needed?

I don't use the vacuum retard at all...

My theory has always been that it was cheaper for VW/Porsche to use the same distributor dashpot, and just leave the advance fitting unhooked.

BTW, some 75+ 914s had the vacuum advance hooked up. At the very least, those cars with EGR did.

--DD

Now, I'm confused... It seems like some are suggesting that I leave both the advance and retard off. They were both initially connected.

Any problem with Jim's suggestion of rotating the body of the distributor and repositioning the spark plug wires?

I would probably try the cut and attach a right angle fitting approach.

Another angle on this whole thing is to get a rebuilt distributor. Parts America has a Cardone reman distributor for $45.99 and a Beck/Arnley reman for $65.99

Worth the cost just to get a working vacuum advance unit even if the rest of the distributor is junk. And who knows, it might turn out to be better than yours anyway.

And if you are getting it just for the vacuum advance unit - then you get a free set of spare F.I. trigger points to boot.

Cardone reman

Beck/Arnley reman

Demick

Demick,
The Beck/Arnley shows the advance port in the wrong place as is my port. Thanks for the info..
Dan

The Cardone shows it in the correct place. But the thing about those images, is they often aren't accurate. They will often use the same image for many listings that simply look similar.

Demick

I ordered one, I'm determined to get this working....

I have personal experience with those "new" Chinese or Mexican vacuum units. They cost me under $5 each, and were NOT worth the money, given the number of failures right out of the box. I sent the whole batch of 10 back when I found 5 or 6 wouldn't hold steady vacuum. The Cap'n

We are suggesting that you use the retard function but leave the advance unhooked. As 1975 DJET system does not have an advance port on the throttle body at all. You can clip that advance tube and cover the hole to keep the grit out, then you can have free movement of the dizzy for timing.

Please elaborate. Is that stock? My stock 75 Djet does not use advance, but only retard.

My bad vacuum unit is causing a fast idle when timed correctly because it won't retard the timing at idle.

As for "Solex," assuming you want to make it work with the stock parts... If the advance tap that's hitting the oil filler bail wasn't being used, then I would think it could be cut off shorter to clear if it is necessary to have it in that position for correct timing. Otherwise flip the bail out of the way and rotate the tap past the bail then put the bail back. If it IS being used AND it is pointed at the bail when timed right, then why not move the distributor one tooth to get it out of the way? Mine is on the other side of the bail, and if the tap approaches the bail it's getting too retarded.

I'll send you a picture of mine later tonight when I get home from work. I'm 80% sure that my distributor is rotated quite a bit CCW compared to yours, which brings to mind the 90 degree switcheroo that I floated earlier.

My distributor drive gear is dead nuts on compared to the drawing in the manual, at TDC, so I think I'm pretty close to where I should be, and it's CCW from yours....

Also, on my '76, I CANNOT get the idle low enough without the retard. I'm sure the retard has some effect off idle, but I think it's main contribution is at idle. This is because of where the port is located in the throttle bore- it gets vacuum at idle, and then immediately is uncovered when you open the throttle.....

As far as advance is concerned, I learned from a thread here a few months ago that once the port was no longer being drilled on the throttle body for advance, it went disconnected. A short hose was put on the advance side of the can, but then tucked neatly out of sight.... from the factory!

Jim

I'm on the same page. Exactly.

Hey. I bought two of those cardone things, and while they DID work, I had to pull out the advance fitting as it too hit the bale of the oil filler.

Good Luck!

b

Ok, I'm home and here's a pic of mine. Maybe not 90 degrees, but it looks like it's quite a way off from yours. Have you checked the orientation of the drive gear in the shaft? Otherwise, how much better can you get with a 90 degree CCW rotation?

Jim
Click to view attachment

I checked the ports and both are open and drawing vacuum. The retard port is drawing at idle and the advance port draws about 10 to 15 In Hg at 2000 to 3000 RPM.

Can I just rotate the distributor?

If you just rotate the distributor body, you will change the timing. If you rotate the distributor drive shaft and the distributor body, you should not be changing anything meaningful. You'll still have to set the timing, but I think you should be able to do that without fuss.

--DD

Ok, after much thought I decided to try to bend the vacuum advance port on the canister...

It worked; I started the bend in a vise trying to only put pressure on the base of the port so as to not damage the canister or pull out the port. I completed the bend with a good pair of needle nose and pliers wrapped in masking tape.

I attached the hose and used a wire tie to secure it to the now bent port, from my picture everything is behind the bailing wire with a fair amount of clearance.

Started right up, I will time the engine tomorrow and take it for a spin and will update.

Thank you

I took the car out for a spin last night, after timing the engine it does run alot better in particular at idle. The cold start fast idle is now working properly. All-in-all I think that this is an appropriate replacement part for our distributors.

Confession to follow: I got the cardone distributor this weekend and too my surprise it looked quite nice, but (1) although the retard diaphram holds a vacuum it does nothing in the way of retarding the distributor (no movment on the lever) and (2) there are no shims at the base of the distributor, I have seen a number of distributors and have never seen one without shims???

Should have listen to the capt'n,

Off to the return line...