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Tue Nov 17, 2009 3:30 pm

My new westy has its brake booster disconnected and bypassed. The hose that normally goes to it for vaccum I believe is bolted and shut off. I cannot find anywhere in the engine bay that its hooked up too. Is it possible that when the PO converted from FI to this carb (damn your black soul) they capped off the booster instead of tapping a hole in the intake to hook it up? My second question is just that, where would I need to connect this hose to to reactivate my booster? I know there is a good chance the booster may be bad, but without it being hooked up, how would I know? Clear as mud?

Tue Nov 17, 2009 3:44 pm

Every progressive manifold I've seen has a vac. pipe sticking out under the carb just for that purpose. 8)

Tue Nov 17, 2009 3:47 pm

I'll double check mine when I get home. I didn't notice it, but it was getting dark. Surely I'm not that stupid, but I could be. :)

Tue Nov 17, 2009 4:00 pm

Kirk wrote: I'll double check mine when I get home. I didn't notice it, but it was getting dark. Surely I'm not that stupid, but I could be. :)

yours may have a pipe plug in it.

Tue Nov 17, 2009 4:27 pm

Kirk wrote: I'll double check mine when I get home. I didn't notice it, but it was getting dark. Surely I'm not that stupid, but I could be. :)

It's on the front side of the intake below the carb, below the idle air/fuel screw....reach in there, you'll feel the plug. ;)

If you wanna hook it up you'll have to pull the manifold and carb off...I would suggest getting a 90deg 1/4"NPT street elbow to exit the manifold as you won't want to bend/crimp your vac hose in there.

Fri Nov 20, 2009 8:50 am

Yep, I found it. Capped off at the base of the carb just like the booster is. Wonder if that means the booster is bad or someone is just lazy. Is it as easy as opening both, running the hose between them and hooking it up to test it?

Fri Nov 20, 2009 9:06 am

Kirk wrote: Yep, I found it. Capped off at the base of the carb just like the booster is. Wonder if that means the booster is bad or someone is just lazy. Is it as easy as opening both, running the hose between them and hooking it up to test it?

Pretty much...do you have the check valve? You can test it without it.

My booster works and is capped off because I just don't like it, yours may or may not work, only one way to find out.

Fri Nov 20, 2009 9:10 am

I dont think I have the check valve, although I would argue that I might, because I dont exactly know what that is at this point. Sounds like something else to learn. Why dont you like yours?

Fri Nov 20, 2009 9:19 am

On a 78 it's in the line above the LH accordian tube.

From Wildthings.

Fri Nov 20, 2009 9:44 am

Kirk, you mentioned base of the carb, the hole, if the manifold has one will be a 1/4" NPT threaded hole, not on the carb but on the manifold. Here is a picture of the one way valve on my bus, black and round inline.

Fri Nov 20, 2009 10:14 am

busman78 wrote: Kirk, you mentioned base of the carb, the hole, if the manifold has one will be a 1/4" NPT threaded hole, not on the carb but on the manifold. Here is a picture of the one way valve on my bus, black and round inline.

A Porsche/411/412 breather and PCV valve with a progressive set up. Do you have vented rocker boxes to go with that to keep the vacuum in the crankcase down and to circulate fresh air through it?

Fri Nov 20, 2009 10:37 am

The valves covers are vented and have air filters attached to each one. The breather no longer has the plastic disk (PCV) in it so it is straight through, where the split in the hose is right before the manifold there is a .120 fixed orifice which controls the flow. Basically a fixed flow crankcase vent system which is easier to tune a carb to.

Fri Nov 20, 2009 10:48 am

busman78 wrote: Kirk, you mentioned base of the carb, the hole, if the manifold has one will be a 1/4" NPT threaded hole, not on the carb but on the manifold. Here is a picture of the one way valve on my bus, black and round inline.

Sorry, I meant base of the manifold, where it meets the carb. I'll fiddle with it this weekend and let you guys know what happens.

Fri Nov 20, 2009 12:13 pm

busman78 wrote: The valves covers are vented and have air filters attached to each one. The breather no longer has the plastic disk (PCV) in it so it is straight through, where the split in the hose is right before the manifold there is a .120 fixed orifice which controls the flow. Basically a fixed flow crankcase vent system which is easier to tune a carb to.

I would think that would lean the mixture. Ive never seen a case ventilated directly into the intake manifold. :?:

Fri Nov 20, 2009 12:59 pm

By having a fixed (orifice sized) feed of air, jetting the carb to compensate is really quite easy.

Fri Nov 20, 2009 1:05 pm

busman78 wrote: By having a fixed (orifice sized) feed of air, jetting the carb to compensate is really quite easy.

Interesting bm! Do you have any pictures of that orfice?
Do you think all that air circulating thru the heads and PR tubes aids the cooling any?

Fri Nov 20, 2009 3:17 pm

busman78 wrote: The valves covers are vented and have air filters attached to each one. The breather no longer has the plastic disk (PCV) in it so it is straight through, where the split in the hose is right before the manifold there is a .120 fixed orifice which controls the flow. Basically a fixed flow crankcase vent system which is easier to tune a carb to.

Now that we've threadjacked this one....

Can you post some more pics of your set-up? I was bored today and hooked up a temp type system like yours (minus the valve cover breathers) with an 1/8"/0.125" orifice and it still pulls a huge amount of vacuum thru the case, and was sucking oil up into the breather hose... It made me get around to replacing my Dizzy O-ring, as that was where the howling vacuum noise was coming from... :wink:

Are you running some kind of regulator besides this 1/8" orifice? I assume your valve covers are filtered/vented to the atmosphere ?

Kirk wrote: Why don't you like yours?

I just don't like it in the snow and ice...I hooked her up today after my experiments with PCV venting, as I won't be in the cold this winter.

The stuff I could get at Ace for $7

Fri Nov 20, 2009 4:35 pm

Did not mean to hijack, just showing a picture of the one way valve on my beast.

The orifice is made from 1/2" brass round stock, 1-1/2" long with a hole drilled through the center, made several from approximtaely 2mm to 4mm, the engine liked the 3mm (.120). I started large and worked my way down, I will try the smaller ones, but so far have been satisfied with the orifice installed now. The tower has three copper Chore-Boys and the breather has another one to separate the oil. The filters are housed near the top of the engine bay and are large metal fuel filters with 1/2" fittings, was not ready to spring $23 each on K&N mini's with 1/2" male fittings. Yes this set up does suck, literaly, can assure you there is no back pressure in my crankcase. I can not say whether it does anything for cooling, maybe a little warn air to the manifold, it does perform a little better in temps below thirty, but that is seat of the pants testimony.This set up is not much different than what American car makers did in the early seventies, instead of trying to find through trial and error a PCV valve that would give a consistent flow based on vacuum signal I tried what Ray Greenwood posted on the STF and used a fixed orifice. If you are sucking oil then you need a smaller hole in the orifice.

Fri Nov 20, 2009 4:49 pm

Nice post...I was looking at getting both heat to the manifold, and less PCP in the case. I see you say yours is 1 1/2" long with the orifice, yet I fail to grasp how that lowers the vacuum. I too have some copper chore boys in my breather box... :wink:

I'll admit my ghetto attempt was just a trial run...I was thinking of adding a pressure regulator into the mix, so it would pull only 3~5 psi instead of full manifold vacuum, and still get the heat.

Fri Nov 20, 2009 5:13 pm

It is not intended to lower vacuum, it evacuates the case at a fixed rate, only "X" amount of crankcase fumes can pass through the orifice at any given RPM.

I am not sure there is that much heat, the air into the base of the manifold is warn, but is getting hit with cold air/fuel immediately, I feel it helps a little on cold days.

I tested vacuum off the dipstick once, at around 3K rpm I had just a little over 3hg.