brake check valve,vacuum canister

[BLACKCARBON]

sorry i could only post here

this is the valve from u.s. plastics corp
does the pic show the right way the valve should be facing

car has 272 cams,ported race build,75mm magnus manifold,apracing 4piston brakes

i currently have a vacuum canister hooked up to the brake booster to help at low rpms.

i just got the valve to see if i can eliminate the vac. can
but unsure which way the valve should be facing.
i tried both ways and it wasnt any better than having the can hooked up.
the brakes are rock hard reguardless of rpms but the car stops.

hooked the can back up and the brakes work fine(not as good as stock though)

would rebleeding help?
anything else i should do to help eliminate the can

thanks for any help

 

[9!'clipseDOHC]

The way you have it is backwards. The check valve allows the brake booster to see vacuum, not boost. It only allows flow from the booster to the intake manifold. The more rounded end is the direction it flows.

Hope this helps!

 

[BLACKCARBON]

so it should be like this

anything i can do to help eliminate the can?

 

[9!'clipseDOHC]

so it should be like this

anything i can do to help eliminate the can?

Yes that is how it goes. I don't have a vac can on mine and it works fine. Why do you have one? What do you mean your brakes are "rock hard"?

 

[BLACKCARBON]

i can only press the pedal about an inch and then thats it, cant push the pedal any further unless i use both feet. brakes work though

i was told the bigger cams,ported head,etc.. mean less vacuum for the booster(something to that effect) and was told to get a vac can. to help fix the problem and it helped.

when i asked around people(with full drag setups) wondered why i had one cause they never had a problem with there brakes.

so im wondering if my booster is shot or i have a leak somewhere.

also where in the line should the valve be placed?
i currently set it up so it sits like stock

 

[9!'clipseDOHC]

I see. Hmm. Do you have a vacuum gauge? If so what kind of readings are you getting at idle?

As far as where in the line to put the check valve, it doesn't matter. Just find a straight section.

 

[BLACKCARBON]

found a problem
checked vac. reading at idle
its 5
with 272 cams it should be around 10 to 15 right?
is it possible my timing could be way off?

 

[9!'clipseDOHC]

found a problem
checked vac. reading at idle
its 5
with 272 cams it should be around 10 to 15 right?
is it possible my timing could be way off?

My vacuum is about 15 at idle, I don't have cams though. 5 does seem low. Are you sure don't have any vacuum leaks?

 

[BLACKCARBON]

no leaks that i know of
is there anything else it might be besides a timing issue?

 

[350war]

Do a boost leak test. This will find the vac. leaks if you have any. Does it run good? Fill out your mod. list.

 

[BLACKCARBON]

no leaks , car runs fine just the "hard brakes" problem.
what are some of the causes of a low vac. reading.

mods:
2.4 lr
magnus im,75mm tb
272 hks
aem ems

 

[BIRDCLAWTSi]

Where are you checking your vacuum from? I am wondering if you have tapped into a ported or manifold spot. Check it where your blow off valve is connected. What does your car idle at?
If you really have 5" at idle i would check your timing marks. Do you have adjustable cam gears too? How does it idle? Do you have a wideband?

 

[350war]

Brake booster could be bad. I would unhook the vac. line to it and block it off. Then check your vac. Even with your cams Thats not a good vac. reading. I'm surprised its not running funny. Also make sure your intake manifold gasket is not leaking. Some causes of low vac. are a vac. line leaking,intake or throttlebody cracked or gasket leaking, injector seals leaking, Timing not set properly. A bad brake booster would more than likely not show up with a boost leak test it has a check valve so its not pressurized. If its diaphram is bad it could cause a major vac leak.

 

[Shadow21]

This may be a stupid question but here it goes. Did you have the motor out of the car for any period of time before this happened? I had this SAME issue with my g/f's 2g when we pulled the motor and let the car sit for about a month or two. After thinking and thinking and thinking i thought maybe some dirt dobbers made a nest inside of the hose.. Well it turns out that really did happen. Check your hose. Remove it and blow into it from the brake booster side. If you cant blow through it on that side then you have an issue with the hose.

 

[BLACKCARBON]

all hoses have been replaced.

What does your car idle at?
If you really have 5" at idle i would check your timing marks. Do you have adjustable cam gears too? How does it idle? Do you have a wideband?

idles fine at around 1k.
have adj. cams + wideband. its an auto too
i checked the belt today, its a bit loose so timing is probably off
brakes worked fine when i had the can hooked up so i doubt the booster could go bad all of a sudden but anythings possible.
gauge is tapped into manifold.
gunna check the tb this weekend and do another test