Bhebert449

Rwcently set the timing on my 69 427. I set the timing advanced 36 degrees when at 3k rpms and it is around 12 at idle. The timing was set with the vacuum advance disconnected. When I reconnect the vacuum canister there is no change to the timing. When i remove the hose from the nipple there does not seem to be any vacuum suction at idle. I don’t have a vacuum gauge but should I be able to feel vacuum suction with my finger?

sug

Is it hooked up to ported or manifold vacuum .My l68 was ported and changed it to full manifold vacuum and advanced the timing ang runs great now.

Bhebert449

Here is a picture of the connection

Here is a picture of the vacuum advance hose connection

sug

That is the correct factory location for emissions , your car will run better with full vacuum . Check you vacuum tank is holding vacuum .It is possible your tank is split in one of the indents on the tank. I unhooked all the vacuum related bits ,wipers and lights so I could concentrate on the engine

Bhebert449

Is there a different location to connect the vacuum advance hose?

sug

Just in front of distributor .

Bhebert449

So I assume the current connection is ported vacuum? It will not produce any vacuum at idle?

7T1vette

That is correct. Ported vacuum has little or no vacuum at idle. After the throttle plate begins to open, ported vacuum attains the same vacuum level as manifold vacuum. It's an emissions "thing", intended to make the [retarded] combustion chamber temps hotter so waste hydrocarbons would be burned rather than spewed into the air via the exhaust system.

3X2

You have it in the factory location. Simply remove the hose, cap the port on the carb and T the hose into the choke pull off hose.

Bhebert449

Thanks for the responses. Another question. Will changing to manifold vacuum help in setting the idle speed. Currently the car is performing great with the timing settings I have but while driving and coming to a stop the engine wants to die. I have to feather the throttle to keep it running. If I adjust the idle up on the carb I get dieseling (run on) when I shut the engine off. Also I noticed the engine is running hotter than normal with the current timing settings.

7T1vette

Most likely it will help your idle problem. It should raise idle speed when you add in the vacuum advance. That will allow you to adjust idle speed down and thereby close the throttle plates a bit more and lean-out the idle mixture. Ideally, you would want to set up your distributor advance curve to 'performance' mode, as Lars Grimsrud advises in the instructional paper he provides. (request it by e-mailing him at V8FastCars@msn.com) If you do that, your advance at idle (when vacuum advance is blocked) should be in the range of 12-16 BTDC.

When you connect the vacuum advance and set idle speed to spec, it should idle well, have good off-idle operation, and improve performance significantly.

Bhebert449

yes. I used Lars’ paper to set my timing. He also rebuilt my carbs. It is a tripower 427. Just trying to get everything set now for best performance. Since now I understand my vacuum advance is connected to ported vacuum I will make the changes to connect to manifold and hopefully I will be good to go. Here is a pic of my manifold vacuum connection. I need to order a 2 nipple connector to connect the vacuum advance can.

Manifold vacuum connection

7T1vette

If that is the line which feeds the power brake booster, it is not your best alternative for connecting to the advance can. The brake booster feed is not normally used to feed another vacuum source. Can you use it? Sure. But it would be best to find a less "important" manifold vacuum source to which you can connect. The issue is a low-probability safety/reliability concern...because it involves your braking system. It would just be "better" to connect it elsewhere.

If that line is NOT to the brake booster, put a "T" in it.