Ported or Manifold Vacuum?
Thread Starter
Instructor
Joined: Jun 2005
Posts: 156
Likes: 0
From: Liverpool NY
Ported or Manifold Vacuum?
I'm a little confused on the ported / manifold vacuum for timing advance. I have a 4 barrel holly with mech. secondary and choke. My timing advance is T'd off the small vac line that attaches to the front right side of the carb. I also have a larger vac line coming off the back of the carb.
Am I using ported or manifold vacuum?
Am I using ported or manifold vacuum?
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
easy to check which it is.......... at idle disconnect the vacuum line off the advance cannister and put your finger over the hole of the hose. If you feel the vacuum sucking on your finger it's full manifold . If you can't feel any vacuum on the line it's ported.
If you have a vacuum gauge you can use that also the same way and it will show if there is vacuum or not at idle.
vacuum at idle = full manifold vacuum
no vacuum at idle = ported vacuum
If you have a vacuum gauge you can use that also the same way and it will show if there is vacuum or not at idle.
vacuum at idle = full manifold vacuum
no vacuum at idle = ported vacuum
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
And here's a little more info;
