Engine Vac. line routing
Thread Starter
Racer
Joined: Nov 2006
Posts: 264
Likes: 0
From: McLouth Kansas
Engine Vac. line routing
Here is my issue,,,,I have a double pumper Holley, it is mounted on a edelbrock air gap performer.
I need vacuum for my brake booster,head lights and modulator valve.
My problem is that the back float bowl sits over the top of the vac. port plug on the intake..so that leaves me with the two ports on the carb base plate,,,a big one in the back and a smaller one in the front.
Can I use the one port in the back of the base plate (throttle plate) for all my vac needs,,,I guess I could tee off the one port,,,maybe..
or put a spacer under the carb and raise it up and put a 45 deg brass fitting in the intake port and use a vac tree off that...
What options does anyone have to suggest that I use.
Thanks
I need vacuum for my brake booster,head lights and modulator valve.
My problem is that the back float bowl sits over the top of the vac. port plug on the intake..so that leaves me with the two ports on the carb base plate,,,a big one in the back and a smaller one in the front.
Can I use the one port in the back of the base plate (throttle plate) for all my vac needs,,,I guess I could tee off the one port,,,maybe..
or put a spacer under the carb and raise it up and put a 45 deg brass fitting in the intake port and use a vac tree off that...
What options does anyone have to suggest that I use.
Thanks
Pro
Joined: Apr 2008
Posts: 596
Likes: 6
From: Irving Texas
Pro
Joined: Dec 2008
Posts: 531
Likes: 0
From: Frisco TX
I had the same issue
The low profile Zip fitting will not work either - I have it as well
Easiest fix is to run a small spacer - a Holley heat insulator works well in that its just thick enough to allow enough clearance to run a low profile fitting.
I would not T off the 3/8 carb port for everything - PCV and the brake booster really need their own source.
I am using the 3/8 carb port for PCV and a dual manifold fitting (3/8 and 1/4) for p/b and all other accessories........bought this fitting from PacePerformance
I am running an L-88 hood so clearance was not an issue for me. BTW, as I found out after the fact, Holley and Weiand manifolds do not have this issue
Good Luck, Ed
The low profile Zip fitting will not work either - I have it as well
Easiest fix is to run a small spacer - a Holley heat insulator works well in that its just thick enough to allow enough clearance to run a low profile fitting.
I would not T off the 3/8 carb port for everything - PCV and the brake booster really need their own source.
I am using the 3/8 carb port for PCV and a dual manifold fitting (3/8 and 1/4) for p/b and all other accessories........bought this fitting from PacePerformance
I am running an L-88 hood so clearance was not an issue for me. BTW, as I found out after the fact, Holley and Weiand manifolds do not have this issue
Good Luck, Ed
Terrorizing Orange Cones
Joined: Oct 2007
Posts: 2,572
Likes: 17
From: Northern CO
I don't have a current picture of my final solution but I ran into the same issue. I also have an L-88 hood of unknown pedigree (was on car when purchased) and thought I could use a C3 vac fitting and a 1" tall spacer, as shown in the following photo:
Wrong. Carb sat a tad too high for hood to close.
I ended up visiting the local hw store and bought a brass, low profile, single port, pipe fitting and switched to a 1/2" tall spacer. Lowered setup for hood to close and gained just enough clearance to keep front of air clearner from rubbing inside hood. Meant to get a pic of that to compare with this one. Can do after work today, if interested.
BTW: had capped fitting in this image. No need with planned Hydroboost.
Wrong. Carb sat a tad too high for hood to close.
I ended up visiting the local hw store and bought a brass, low profile, single port, pipe fitting and switched to a 1/2" tall spacer. Lowered setup for hood to close and gained just enough clearance to keep front of air clearner from rubbing inside hood. Meant to get a pic of that to compare with this one. Can do after work today, if interested.
BTW: had capped fitting in this image. No need with planned Hydroboost.
Instructor
Joined: Jan 2006
Posts: 228
Likes: 1
From: Warwick New York
you must check to see what vacuum your distributor needs. I would say a 76 vette needs zero vacuum at ideal while the rest require constant vacuum. Usually there are a location for both type of vacuum. Also Summit carries lots and lots of vacuum fittings.
Last edited by captl27; Mar 3, 2010 at 08:05 AM.
