Air Gap Manifold Brake Booster Line Clearance

[toofun]

Got an Air Gap Manifold and am running a holley carb on top of it. Problem is when I put the carb on top of the air gap manifold, there is not any room to attach the brake booster vacuum line under it. The hole is literally parallel with the carb opening making it totally usesless!!! Only thing I can guess is that Edelbrock really wants you to use JUST THEIR CARB!!! and didnt even consider the fact that others may be running Holleys!! The only way I can make it fit is to use a 1 inch spacer between the carb and the manifold. I dont want to do that because of clearance issues and a good chance I will lose some torque( I have heard that the spacers can actually hurt you instead of help) So what do I do? Is there another place I can attach the brake booster line? Can I TEE it off the same line that goes under the back of the carb with the PCV Valve? Any help or ideas would be greatly appreciated.

Thanks
Mark

[CAMAROBOY69]

I have a Holley 750 Double Pumper 0-4779C with manual secondaries on my Edelbrock Air Gap and im not sure what your talking about. I dont have a spacer. My line runs from the back of the carb to the booster.

[69rs]

Because of this issue I run my booster off the carb instead of the manifold. There is so little clearance under the carb, I even had to cut 1/4" off the brass plug I used in that location.

[toofun]

Thanks Guys,

Only question is, if you run the hose from the back of the carb to the brake booster then where to you run your line for the PCV? Do you tee them off the back together?

Mark

[CAMAROBOY69]

I believe I plugged that hole in the intake and just used the back of the carb only. Would that be the possible reason I am having brake booster problems or not. If not then ignore that statement. Regardless my intake is plugged and the carb runs directly to the booster.

[Travis B]

I believe I plugged that hole in the intake and just used the back of the carb only. Would that be the possible reason I am having brake booster problems or not. If not then ignore that statement. Regardless my intake is plugged and the carb runs directly to the booster.


What kind of booster problems are you having....?

Are you running a pcv?

Mark-Sorry I am not real familiar with the air gap intake....Does it have another port on it somwhere....I have seen a few that have a vacuum port added into them in the back below the carb???
I am not sure if you could tee it off or not? I am sure someone will chime in and let us no!

[CAMAROBOY69]

Well im having some sort of brake problem that no one seems to be able to figure out. I even took the booster out and took pics of everything I have including the Master cyliner and all the rods that hook to it. SO my guess was the brake booster. But I never considered the fact that I am running directly from the carb. I really dont think that matters at all though but it was something I realized by reading this thread.
To answer your question I just dont have any pedal at the top. I have an entire thread about this so we dont hyjack this one. Urgent my car just wont stop (https://www.pro-touring.com/forum/showthread.php?t=7342)
I have a PCV for one side of the valve covers that I run to the air cleaner.

[Travis B]

Camaro boy-The vacuum line running from back of the carb shouldn't be the problem! That is where I would run it from also!

[CAMAROBOY69]

Ok I didnt think so. just making sure. All my other vehicles have run the same way. Cool that eliminates that as the problem. Im really sure its the booster but anyway enough about me and thanks for that quick answer.

[toofun]

Hey Camaroboy,

If I remember correctly You are running a pretty healthy cam in that motor. That could definately be causing the booster problem. Or you could have a small leak in the booster itself causing loss of pedal. I have a similiar problem but and thinking of switching to a hydroboost to eliminate it all together.

Mark
TOOFUN

[CAMAROBOY69]

Even with the old pathetic engine I didnt have very good brakes at all. I am almost positive its the booster. The brakes worked good enough at Gingerman Raceway but definetly could be and will be a lot better.

[69rs]

where to you run your line for the PCV? Do you tee them off the back together?

I have a tee in the line between the booster and the carb for my PCV.

[CAMAROBOY69]

Would that cause gases to go into the booster? Im just trying to see how that would work. I thought the carb pushed out air for the booster. If so wouldnt that be either pushing the gases back into your engine or would that push the gases into the booster?
Oh wait the PCV valve is one way so if you force air to it it from the opposite direction it will stay closed.

[Steve68]

I had the same problem, used a 1" spacer, YES, elbabrock want you to use there carb, the BB is worse, the port is so close to the runner you can't use a factory style vacuum port, not a big hurdle, but it can be fixed, Steve

[69rs]

I thought the carb pushed out air for the booster

Carbs suck (vacuum)! The booster and PCV require vacuum.

[Scott Parkhurst]

If you lose power with a spacer plate, you're using the wrong spacer plate. If you use an HVH or Wilson Manifolds 4-into-1 tapered spacer, you will crispen the vacuum signal to the throttle blades (it's like a funnel in that respect) and testing has shown power to increase all over the rpm range. Throttle response is better too. These things really work.

SP~

[CAMAROBOY69]

I guess i just learned about the booster then. THat is really strange how it sucks from the booster. I didnt realize that. Hmm time to research how boosters work. So in that case thats a good idea to have the T for the Booster and the PCV. I will probably do that now. I like that idea instead of a breather. :)
I just read this http://auto.howstuffworks.com/power-brake2.htm and it was very helpful.

[toofun]

Good idea to have both I would think. You should have a PCV on one cover and a breather on the other one.

[6'9"Witha69]

That is how it is meant to work. The breather does just what the name implies, it allows air to come into the Crankcase and the PCV sucks it out. It is part of a system.

Scott is correct, there are MANY spacer designs out there and several work in each engine combo.

I run Manual brakes so i am of no help in that area.

[Steve68]

I forgot to mention that I plan on running one of the ones Scott metioned, BUT I need a cowl hood, My friend has HVH super sucker with NOS bars in it, I might run that plate, Steve

[andrewb70]

That is why you should all check out the new Weiand dual plane manifolds. Here is a sneak peek at the new Action Plus for Vortec heads. It was worth 24HP over the 2116 and even showed 4-5HP over the 7116. As a bonus, you won't have to worry about your Holley carburetors hitting the vaccum fittin in the rear runner.

https://static1.pt-content.com/images/noimg.gif

Link to a Super large image (http://www.holley.com/data/products/pictures/large8121.jpg)

Power Graph in PDF (http://www.holley.com/data/Products/Media/8121_Power_Curve.pdf)

Andrew

[Railing68]

I run the 7501 AG intake and had the same issues, edelbrock makes a low profile fitting 8096 I believe. However, It still hit the fuel bowl. I used a thick base gasket approx 3/8" thick and clearance was suffucient. I had a 1" 4-1 spacer that I had always run and wanted to not use it. I haven't been disappointed w/o it. If you are not running a PCV then you can just go off the fitting at the rear of carb. SS

[Steve68]

Good idea Andrew, I like Why-and's manifolds, thats why I grabbed the one fron 3rdgenbu(name?) when he was selling, Steve

[David Pozzi]

I used a 3/4" thick plate on my 67. Don't T anything else on that vac line, especially a pcv valve.

Regardless, the booster won't cause excessive pedal travel unless it's badly broken inside, it's just a straight through push.

Andrew,
Wish I'd known about that Weiand manifold, just bought a 7116 E'brock for our ZZ383/425 but we are installing it in just a fiew days.

[gmachinz]

Since Holley owns the Weiand line, it makes sense that their manifolds serve to be used with their carbs. Without a cowl hood, 1" spacers might be a problem. Otherwise, can't you use a 90-degree tee from the back of the manifold for the brakes and use the rear carb. port for the PCV? Of course, if you have a vacuum modulator, then that's another issue. I have a list of parts I ALWAYS scavenge from wrecking yards whenever I'm there-one such item is the often forgotten about 1/2" pipe fitting vacuum tee for the manifold. They usually incorporate two or three various sized fittings for diff. accessories and can be buffed to imitate stainless even! Worth their weight in gold when you need one to do the job right! -Jabin

[andrewb70]

Andrew,
Wish I'd known about that Weiand manifold, just bought a 7116 E'brock for our ZZ383/425 but we are installing it in just a fiew days.

David,

No worries. We are actually getting ready to test a slightly bigger and slightly taller manifold. It will be called the 8151. It will be a Weiand Stealth. We are actually using a ZZ383 as the test mule. I will let you know how it works. You may want to e-Bay your 7116. Send me a PM.

Andrew

[cad]

I just switched to the Victor Jr which does not have a vacuum fitting port.
I have a comment and a question for David Pozzi.
1. I made the honest mistake when I switched from my old Weiand of not having a breather with my pcv valve. That intake had the old style filler neck on it, and I capped it with a K&N clamp on breather.
I had a pcv valve in one v/c and a plug in the other v/c. We never did drive it on the street before going to the drag strip last Sunday after the swap. The first pass was OK. The second pass pushed some oil out the front/rear of the intake. Not to give up on a nice racing day (chance for a Wally), we corrected that leak. The 3rd pass was not good. It pushed the pcv valve out the v/c and blew oil all over the hood, inner fender, and the firewall. We cleaned that and then it dawned on us.....no breather...

Point: You should run a pcv valve AND a breather!
The rest of the day, it ran fine. Didn't win the Wally, but we didnt make a bigger mess on the track.

2. David, I do have a tee now for the pcv and the booster since the Victor Jr has no fitting avail. Brakes work as good as before.
I thought the engine pulled on the booster to create the vacuum inside of it.
What is the issue with that?