Distributor questions Options

[mike_the_man]

Hi all,

I have a couple of questions about distributors:

1) I'm putting in a pertronix, and on the old points, there was a ground strap that was connected to the bolt that holds the points in. In the instructions for the Pertronix, it doesn't mention anyhting about the ground strap. Should I use it? I can't see it being a big problem, but the Pertronix mounting plate might not sit flat if the strap is used. Any thoughts?

2) I have a 74 2.0L. On the vacuum advance there are two ports, but on the 74, only one is supposed to be used. Which port is it, and what does it do? Is there any way to test the vacuum canister to make sure that it is working?

Thanks guys,

[McMark]

Originally there was a braided copper wire that was soldered to the body and the advance plate. The rebuilt units have a wire that screws on. Sounds like a rebuilt distributor or somebody's "fix". I'm not sure that you need the strap with a Pertronix because it has a ground wire. I would put it in to be sure. It won't hurt any.

You can test the vacuum advance by getting a piece of hose and sucking on each port and watch the advance plate. Suck some pressure and then cover the hose with your tongue to keep the pressure. If the plate slowly moves back then your canister is leaking. If you've got a handheld vacuum pump (MitiVac) then you can use it. The point is that you should be able to pull a vacuum on either side and it won't bleed down. As for what to hook up where, the ports are different sizes and match the ports on the throttle body. I believe the 1.8 L-Jet cars only have vacuum retard.

[Dave_Darling]

I'm pretty sure the Pertronix doesn't need the ground, but it does need to have the floating breaker-points plate move freely. If the ground braid is breaking, chances are pretty decent that the plate needs replacing. You can use the one from an FI'd Type III VW.

The vacuum advance port is the one that does not get hooked up on many 74+ 914s. That is the one that points away from the distributor body. If your throttle body has two fittings on it, however, then both do get used.

--DD

[mike_the_man]

The breaker point plate seems to move freely. I'm assuming that it's the plate that vacuum advance arm attaches to. If so, it moves both ways.

What does the other vacuum port do? My throttle body only has one fitting, so the advance isn't hooked up, so what is the other port doing? I'm guessing that it's a vacuum retard?

Thanks,

[garyh]

The breaker point plate seems to move freely. I'm assuming that it's the plate that vacuum advance arm attaches to. If so, it moves both ways.

What does the other vacuum port do? My throttle body only has one fitting, so the advance isn't hooked up, so what is the other port doing? I'm guessing that it's a vacuum retard?

Thanks,

The 2nd port is a vacuum retard. It works only at idle, a (poor?) attempt to make the car pass somg checks.

The ground strap comment troubles me. There should be a braid that connects the two halves of the breaker plate. If this is missing, the car will run poorly. (BTDT) Only know fix is replacing the breaker plate; all my attempts at re-welding have failed.

The pertronix gets its ground through the breaker plate.

[Dave_Darling]

Hmm, I thought the Pertronix had its own ground wire? I know the Crane setup does.

If the Pertronix does not have a specific ground wire, then you really do need that ground braid that we're talking about!

The two fittings are vacuum advance and retard. They are there to change the timing depending on the engine load, which is generally a Good Thing. If there is only one fitting on the throttle body, then the advance fitting (the one pointing away from the distributor) should be left open to the air.

--DD