proxemics

this is my first time doing this setup and when putting the carb and intake together I noticed something I don't know what to do about
thier is a hole at the back of the intake that became under the carb when I put it on the intake what is this hole for? should it be for a vacuume line or should I block it ? If it's for something how can I do it because thier is not much space under the carp

the carb is duple bumper

I appreciate any help

Nebu

thats vacuum for the brake booster. but you won't get a fitting under the fuel bowl. you can plug the hole at the intake and take a t-fitting and connect the brake booster and pcv together to the rear vacuum port at the carb.
but you won't get full brake assistance...

nebu.

proxemics

thanks man do you have any pics for that setup

Rick King

yea that hole will need a plug put in it. I just check my performer with a 600 cfm holley and the hole is exposed, more room for the proper install of the brake booster vacum line.. If the car was mine I would get the manifold machined in an appropate place to hook up the vacume properly or get a vacume canister. You might be able to get a spacer for the carb that would allow you to use the factory port on the manifold. However this will change the way the intakes works in relation to the motor. sometimes spacers are not good for a motor.
later and

GB

rk

jstoltz

iTrader: (16)

get an aluminum 1/2" spacer and use a 14x2" drop base air cleaner I have the spacer part done on mine but still haven't got around to the air cleaner yet. I can show pics if you want em.

SSP6

i dont know what cam you're running, but i have the same setup tht you do only on a vortec motor, and i'm using a 1" spacer for power, and it just so happened that it worked out perfectly to throw a hose adapter in there.

bluegrassz

iTrader: (3)

I ran into the same problem. I tried T-ing off the brake booster and PCV and had no brakes at all. I dont have the room for a 1" spacer, but I might fit a 1/2".

I am going to run a vaccum can also.

Air_Adam

I'm going to have the same problem in a few weeks, when my 650 double pumper gets here.

I was thinking... is there anywhere in the plenum or a runner that would have enough meat to drill and tap a hole for a fitting? That would be the best way to do it.

The Torker intake I had on the engine before the currect RPM AG intake had it right... in the back of the plenum, pointing straight back, about 1" below the carb base. It was just below the big port on the back of the Holley.

Think there might be enough meat in that spot on the RPM AG intake to drill and tap for a fitting?

jstoltz

iTrader: (16)

there could possibly be enough meat to do it but why not just use the 1/2" spacer and low pro air cleaner. mine fits fine and that is with new ES poly motor mounts
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stock 87 Iroc hood too. I will probably have to change hoods with my next motor though. 18* spyder.

Air_Adam

Because I already have little enough hood clearance with my 14" air cleaner... so little I have to use a regular nut and a shaved down stud... i can't even use a wingnut, lol.

jstoltz

iTrader: (16)

change filter size to 14x2" and use a low pro billet air cleaner nut. similar to a wingnut but better looking.

Confuzed1

iTrader: (4)

Try using a "low profile" vacuum fitting. It's a 90 degree fitting, and if used with a 1/2" carb spacer, it works. I tried teeing off the rear carb vacuum port to the PCV and brake booster, but I barely had any brakes and almost ran it into the back of another car!!......I'll never do that again.

From now on, my brake booster gets it's own vacuum source, or I use a can.

Air_Adam

I could tee it off the PCV, but I know the problems that come with it, so I'm not even going to try it. Its not worth the risk.

But... I was looking at my engine last night, and I noticed the bosses cast into the manifold near the end of each runner. The ones for N2O nozzles I think?

Would one of these have enough meat to tap for a vacuum fitting? Would this maybe be a bad place to put a vacuum fitting, being so close to the head?

jstoltz

iTrader: (16)

I don't think I would try it there those are actually intended for tapping in injector and using a throttle body instead of carb you will be right in the intake runner on the head. just go with the 1/2" spacer and use a regular 90* vac fitting the low pro was a waste of money I got one from edelbrock for $20 and even called first and they said "yeah this is what you need to make it work" HA wrong still had to use the spacer. it will all fit fine just get the lowest drop base, I think 1 3/4" drop and use a 14x2. Jegs has one that will work fine cheap too. can't remeber the part number though just give me a day or too or call them up. good cs there they could help too.

Air_Adam

Whats so bad about that? Its just a different spot on the intake runner....?

rjmcgee

14 x 2 filter in a drop base housing isn't a great way to go. The lid for the filter is only about 1/2" - 3/4" above the carb. Best to make a 3" filter work.

jstoltz

iTrader: (16)

hasn't had a negative effect on mine, I tried using a 3 and 4" filter with no gains. a friend of mine had better results using a 2" drop base with cold air intake also. so I definitely wouldn't worry much about height carb will only ingest so much anyways.

Air_Adam

Ok, I found something that worked. I thought I'd put it in here for the next guy that will do a search on this.

What I did, is drill and tap one of the N2O/injector bosses on one of the intake runners for a brass hose barb fitting (5/16" thread, 3/8" hose barb). They are just barely big enough for this, but work great. There is plenty of metal in those spots for this job. Just remember to use a thread tap that is a 5/16" pipe thread (NPT) and not a standard 5/16" thread.

I used the boss on the #7 runner (back, drivers side) but any of the 8 runners would work just fine.

Once you have that done, you can plug the hole behind the carb mounting flange. It uses the same size plug as the two coolant passage holes on the back of the intake.

Done!

EDIT - I used that fitting because I used this for the brake hose.

F-BIRD'88

My power brakes are simply Tee'ed into the PCV vacuum hose. Power brakes work fine. A lot of bother for nothing.

Air_Adam

Meh... the intake was off anyway, whats another 5 minutes to try this out?

Justin 87 GTA

iTrader: (3)

hmmn, what the heck am i gonna do since i have the vortech carb enclosure.?

Rayzor32

iTrader: (1)

get a 90 degree fitting and a 1/4" thick gasket and a drop base air cleaner, I ran into the same problem but my carb doesn't have a pvc port so im running breathers

Justin 87 GTA

iTrader: (3)

i don't even know i fi need pcv valce anymore, but the vortech enclose doesn't need and aircleaner..

Rayzor32

iTrader: (1)

i decided against pvc im running breathers. My carb doesn't have a vac port on it or I would've just blocked off the port on the manifold but i needed the port for my brakes. 3 carb gaskets + 90 degree fitting + 14" holley drop base = barely fits but it works. Also DO NOT OVERTIGHTEN THE CARB STUDS you will pull the threads out on this manifold make sure the carb studs are all the way in, it doesn't take much to pull out the threads

LilJayV10

iTrader: (5)

I am using the same intake/carb setup on mine. I am using a canister but the brakes still aren't that great. I am using a tee out off the back of the carb.

Where can you buy the low profile vacuum fitting?

Is it better to run the PCV from the intake or the carb?

Thanks!

jstoltz

iTrader: (16)

you can get the fitting from edelbrock . not cheap and if you use a 1/2" spacer a regular fitting will work. Could always swap to hydroboost and then you eliminate the problem all together and have better brakes when you are done. (this is what I will be doing)

LilJayV10

iTrader: (5)

I finally found the 90 degree fitting this week. Spectre makes it and the damn thing was 13 bucks. Probably cause it was chrome.

I tried to find a regular brass 3/8npt to 3/8 barb fitting but had no luck. I put a new ignition system on my car from summit so i ordered a 1 inch spacer.



Now I just need to find out what hood to buy.

wrsjr

I have the same intake and a 700DP. I originally had a 50cc accel pump on the back so I had to run a 1" spacer. I ended up plugging that port and using a t fitting for my power brakes and pcv. My brakes do pretty well. I went with a Goodmark 2.5" steel hood. I sometimes wish I went with a different hood, but I wanted steel instead of fiberglass.

Saigon_Bob

iTrader: (2)

I've read alot of the posts here and don't tee off of the brake booster and pcv. you are asking for trouble.

as for running carb gaskets stacked up, you are asking for vacuum leaks

kowboy59

iTrader: (8)

What he said. Get a 1" or mb a 1/2" square bore spacer which actually helps the carb more too. Then you can get the fitting and be done with it. Hopefully thats what you are doing

Rayzor32

iTrader: (1)

yeah thats the same spectre fitting i got except i just used 3 carb gaskets to clear it, and no vacuum leakes cuz i rtv'd them all together.

Saigon_Bob

iTrader: (2)

lol... well thats original... but i would avoid stacking gaskets. a carb spacer is fairly cheap and helps the motor.

I had the same issue with my Demon Carb back when i had it, it only had one vacuum fitting for with PCV or power brakes and my motor would leak like a civ w/o a pcv

Rayzor32

iTrader: (1)

I would need a cowl hood if I went any higher than it is now

kowboy59

iTrader: (8)

Do it!!!!!. Maybe a drop base air cleaner????

Rayzor32

iTrader: (1)

i already got the drop base air cleaner and it BARELY fits

jstoltz

iTrader: (16)

switch to a 2" filter you only NEED 3/4" above the carb anyway. Doesn''t hurt performance as long as you use a good filter.

Xenocide4077

does anybody have the part number for that spectre 90 degree adapter?

CamarosRUS

Also need to find a 90 degree adapter....but need a spacer I assume to get it to clear.



So are you saying it make a difference if you T in the brake booster to the PCV line as opposed to Ting in the PCV line into the brake booster???


I liked Air_Adam's idea but I want to keep my bosses undrilled in case I want to go N20 in the short future.


Liiljay....it may just be me but it looks like you have a leak where the carb bolts to the manifold due to the discoloration.

Rayzor32

iTrader: (1)

autozone has got the fitting. You don't need a spacer but you will either need to triple stack carb gaskets or buy one of those extra thick insulating ones.

Mikz86TA

iTrader: (4)

My .02 cents.

On my car I have the Perf RPM and its a stock hood TA. So Im maxed on clearance upwards.
I plugged that hole and use the rear carb port for Vaccum to the PB. But it was weaker so I have a Crane Vacc Canister.
Holley intakes you will notice have that intake port moved over futher to clear the DP Pump on thier Holley carbs.
Edel I think does this on purpose so you will be inclined to buy their crappy Carter....er....Edel carbs. LOL

Rayzor32

iTrader: (1)

my thoughts exactly while i love the eldebrock intakes i hate how the fitting is in the way and i agree that its on purpose so you are more inclined to use an eldebrock carb

1320_Guy

iTrader: (3)

Just do it the right way and drill and tap a port farther back on the runner.

.5 or .75 if an inch is not all the clearence you need between the carb and breather. You need as much as you can get, any time you restrict air flow you hurt horsepower. Weather you can feel it or not its happining.

A carb spacer is for tuning purposes, it can eather help or hurt performance. Every motor is diffrent. The guy that posted the picture of his spacer, You are using the wrong spacer. With an open spacer on a duel plan intake you are hurting performance.

Also for the guy not running a pcv valve that is a bad idea. You are building crankcase pressure that is only being pushed out with more pressure (crankcase presure makes it harder to push the pistons down in the cylinder= less horsepower).

Confuzed1

iTrader: (4)

Already been there and done this - on a Camaro. I ran a Prof. Products "Crosswind" intake and a 650 Speed Demon carb (same as airgap). You have two real choices...

Choice 1: Buy a 90 degree "low profile" vacuum fitting (Edelbrock sells 'em) - and run a 1/2" carb spacer with a Mr. Gasket 14" "Low Rider" air cleaner with a 2" thick element - a 3" element won't fit, don't bother. A stock (Camaro) hood will shut with less than 1/2" to spare with the 2" element. Make sure the air cleaner stud dos not protrude above the upper lid on the air cleaner!! Unless you have a 500 HP engine, with a serious free-flowing exhaust, you're not choking it. That's the route I took - it works fine.

Choice 2: Plug the original vacuum port under the secondary bowl, and re-drill and tap threads for a new port further back - that way, no carb spacer needed and you might get away with a 3" air cleaner element, especially if you use the "low rider" air cleaner.. -In hindsight, it makes more sense to just bite the bullet and do it this way - costs less too.

-There's more unwise choices too - like "teeing off" and combining the PCV and power brakes. You'll change your mind quickly once you discover on a quick stop, the power brakes won't be there. I did.

Sorry, but for you Firebird/GTA guys and gals - choice 2 will most likely prevail...

-Hope this helps!!

Rayzor32

iTrader: (1)

Where did you hear that? I don't see how that would be happening the crankcase pressure would just be ventilating through the breathers instead of being drawn into the intake with a pvc valve. PVC valves were an emissions device.

CamarosRUS

PCV valves are not just an emissions device, do a quick search. I'm not saying you will automatically get blowby without one but a PCV (positive crankcase ventilation) creates a small vacuum inside the motor pulling in fresh air from the breathers (on the opposite valve cover). This can help keep the oil slightly more fresh as well and, you guessed it, act as an emissions device.




Back to the thread...is there really enough meat to tap into one of the rearward runners on the manifold? This is very simple and can be done cheap (for those not wanting to try to tackle the project) but I would have to do it and have it crack or, by some odd chance, not seal correctly.


(BTW...I just inspected my Performer RPM Air-Gap after reading some Q.C. issues about them on here and found my dizzy boss is not level!!!! Making a new thread for those who may want to read more or help.)

jstoltz

iTrader: (16)

from what I have heard (remember this is hear say) not running a pcv valve will usually cause more sludge in the oil that is really the only draw back but if you are only putting 5000 miles or less on the motor a year and change the oil every spring this isn't a big deal on a dd I think it could present a problem. If anyone needs a 1/2" carb spacer for a dual plane intake I have an aluminum one I'll get rid of cheap just pm me I am going with a big block and hydroboost so I don't need it anymore.

CamarosRUS

PM sent.

bluegrassz

iTrader: (3)

Im going to add a 3rd choice:

I was upgrading my carb from a 750vs to a DP and bought a Holley 750 Street HP carb. It has the rear port for the brakes, one in front for the PCV and one for either the advance on the dizzy or my mod vavle on my TH350 trans. Not to mention a fitting on the front metering block.

Oh yeah, I went with a 4-hole 1/2 in phenolic spacer with my RPM airgap. It reduced the temp of the carb quite a bit.

Rayzor32

iTrader: (1)

I see. yeah I do get some blow by and the oil gets dirtier quicker I think I will PVC breather when I get a new carb with a port for it next spring.

CamarosRUS

Glad I could help