2.0 Dizzy Question, Maybe I am just an Idiot Options

[Mblizzard]

Ok 73 2.0 built to a 2056. Currently running points. Checked dwell and set to specs. I was setting the timing and I have a timing light that you can set in the advance.

1st question: Can you use the advance setting on the timing light instead of the 27 at 3500 rpm?

2nd question: My dizzy has 2 vacuum ports. One is advance and one is retard. My throttel body only has one vacumm port for the dizzy. Do I need both hooked up?

3rd Question: Do I have the vacuum line on the correct (advance) side?



4th Question: when I check the timing (just for fun) with the vacuum hose hooked up as shown the timing is not anywhere close to 27 at any rpm. That seems odd.

[Mblizzard]

So we have a couple of differing opinions on the correctness of the vacuum advance hose connection.

After setting the timing and connecting the vacuum hose as shown, the engine speed decreases greatly. Which to me says that port is retarding the timing. When I switch sides, the engine speed increases.

Anyone have a definitive answer as to which side of the dizzy is advance and which is retard?

[r_towle]

So we have a couple of differing opinions on the correctness of the vacuum advance hose connection.

After setting the timing and connecting the vacuum hose as shown, the engine speed decreases greatly. Which to me says that port is retarding the timing. When I switch sides, the engine speed increases.

Anyone have a definitive answer as to which side of the dizzy is advance and which is retard?

It's a diaphragm hooked to an arm that moves the advance plates.

Open the top of the distributor and look at it.

When you apply vacuum to the port farthest away from the distributor, you pull the advance plate arms and thus add advance.
When you apply vacuum to the vacuum port closes to the distributor, you push the arm which retards the advance plates.


If you have no vacuum at all hooked up, the advance plates function only by centrifugal force and will eventually (at 3500 rpms) get to full advance.

The vacuum advance is to assist in helping you accelerate by adding in some advance earlier than at 3500 rpms to give you a smoother acceleration.

The vacuum retard is to help with emissions to retard the timing faster to reduce over run and higher idle, and burning extra fuel.

You set the timing with nothing hooked up so you are only using the centrifugal advance, thus why you need to set timing at 3500 rpms....so you know for a fact that you are looking at full advance.

Please explain your symptoms in this thread.....
How you are doing timing, and how lubricated the whole advance mechanism is might be affecting your results.

[Mblizzard]

So we have a couple of differing opinions on the correctness of the vacuum advance hose connection.

After setting the timing and connecting the vacuum hose as shown, the engine speed decreases greatly. Which to me says that port is retarding the timing. When I switch sides, the engine speed increases.

Anyone have a definitive answer as to which side of the dizzy is advance and which is retard?

It's a diaphragm hooked to an arm that moves the advance plates.

Open the top of the distributor and look at it.

When you apply vacuum to the port farthest away from the distributor, you pull the advance plate arms and thus add advance.
When you apply vacuum to the vacuum port closes to the distributor, you push the arm which retards the advance plates.


If you have no vacuum at all hooked up, the advance plates function only by centrifugal force and will eventually (at 3500 rpms) get to full advance.

The vacuum advance is to assist in helping you accelerate by adding in some advance earlier than at 3500 rpms to give you a smoother acceleration.

The vacuum retard is to help with emissions to retard the timing faster to reduce over run and higher idle, and burning extra fuel.

You set the timing with nothing hooked up so you are only using the centrifugal advance, thus why you need to set timing at 3500 rpms....so you know for a fact that you are looking at full advance.

Please explain your symptoms in this thread.....
How you are doing timing, and how lubricated the whole advance mechanism is might be affecting your results.

The main symptoms are overall lack of power and poor fuel mileage.