Vacuum lines when changing carb
Thread Starter
Instructor
Joined: Feb 2012
Posts: 173
Likes: 1
From: Federal Way WA
Vacuum lines when changing carb
As the title says going to a 4150 700cfm Holley double pumper. My question is where can I hook up all the vacuum lines since the new carb doesn't have the same number of vacuum ports?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
The power brake line needs to be from a large fitting on the carb baseplate and no other vacuum line should be hooked in with it. Other vacuum "feed" lines can be bundled together, if appropriate.
One or more stock lines might be fed with 'timed' or 'ported' vacuum. The others will be fed with 'manifold' vacuum. These lines need to be fed in the same manner from the ports on the new carb. You will have to determine which are which from new carb instructions/information and from Chevy Service Manual or info from this Forum (for stock carb fitting types).
One or more stock lines might be fed with 'timed' or 'ported' vacuum. The others will be fed with 'manifold' vacuum. These lines need to be fed in the same manner from the ports on the new carb. You will have to determine which are which from new carb instructions/information and from Chevy Service Manual or info from this Forum (for stock carb fitting types).
Drifting
Joined: Jul 2009
Posts: 1,532
Likes: 14
From: Dallas-Fort Worth TX
dgheinen, I have a newer Holley Street HP 4150 carb. I recently re-routed my vac lines.
I was splitting the brake booster with headlights, which as 7T1 pointed out is not good practice.
My Carb has 3 manifold vac ports and 1 ported vac port.
I run my brake booster dedicated, from back of intake vac port.
I was splitting the brake booster with headlights, which as 7T1 pointed out is not good practice.
My Carb has 3 manifold vac ports and 1 ported vac port.
I run my brake booster dedicated, from back of intake vac port.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
We don't know what year car you have nor if it still has the factory setup for emissions control, so there is no way to be specific about how to 'plumb' whatever vacuum lines you have. Sorry.
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
