Vacuum source / brake booster hose

[MildSeven]

123tune / Weber dcoe 45s

 

My 02 is in storage for the winter, so I'm doing some homework/purchases for early spring.

 

I've read that a easy source of vacuum is to T off the brake booster vacuum hose using a anti-pulse valve (http://vwparts.aircooled.net/Anti-Pulse-Valve-for-Vacuum-Advance-Distributors-p/anti-pulse-valve.htm).

I've also red that it is best to use all 4 runners for vacuum reading.

 

Could the experts please share their thoughts?

 

...also, what is the inner diameter of the brake booster hose (since mine is in storage)?

 

thanks,

Anthony

 

 

Edited January 24, 2017 by MildSeven

[Harv]

The booster comes off one runner usually. Then goes through a non reversing valve to the booster. If you were to take the source from here, you will (or should) run it to a reservoir to dampen the pulses. This reservoir should have at least the volume of a soda can or such. If you take off from each runner you can reduce the size of the reservoir. In my car with ITBs I use a 13 inch long piece of 1/2 inch copper pipe with caps on each end. The idea is to dampen the pulses to get a smooth vac signal. 

 

John

[HBChris]

RealOEM.com is your friend, 12x19 hose dimension

[TobyB]

Personally, I wouldn't mess with the booster hose-

it's a hard, spring- lined thing, and not really easy to splice into. 

Plus, it's right out on top, where any plumbing looks like... well, plumbing.

 

Someone a while back drilled and tapped underneath the manifold- that looked very clean...

 

t

 

[MildSeven]

thanks guys.

 

I'm just not really a fan of drilling 4 holes in an intake... but if it really out weighs using the brake booster. I'll do it :(.

[MildSeven]

2 hours ago, HBChris said:

RealOEM.com is your friend, 12x19 hose dimension

 

thanks!

so inside dimension is 12mm and outside is 19mm

[HBChris]

Correct

[Guest edgarcia737]

This topic may have solve my problem. I'm running 40 DCOE's, Cannon manifolds, stock cam. So I've had this stumble off idle and a roughness (which I felt was a small vacuum leak). So while playing around with different jets, etc. I noticed the pulsing in the booster hose. So I removed the booster hose and plugged the manifold, wow, smooth idle and no more stumble. So now I'm driving around with no power brake assist ( which I can live with). So I'll fabricate a vacuum reservoir and see if that helps. But I'm also thinking maybe I should use IE intake manifold. Any opinions?


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[TobyB]

Quote

I'm just not really a fan of drilling 4 holes in an intake

Yeah, I can see that.

I bet, for a tunable ignition, you could just tap 1 (or maybe 2&3) and use a canister and small tubing (and maybe some restrictors)

and get a useful signal.  Or maybe make a small metal tee to put in before the nipple on the brake

booster signal.  All I meant was, cutting and splicing the brake booster line itself would bug me, slightly, aesthetically.

But it's not my car!

 

t

 

[MildSeven]

18 hours ago, TobyB said:

Yeah, I can see that.

I bet, for a tunable ignition, you could just tap 1 (or maybe 2&3) and use a canister and small tubing (and maybe some restrictors)

and get a useful signal.  Or maybe make a small metal tee to put in before the nipple on the brake

booster signal.  All I meant was, cutting and splicing the brake booster line itself would bug me, slightly, aesthetically.

But it's not my car!

 

t

 

 

thanks Toby.

 

I already purchased that anti-pulse valve off ebay for $25usd. If anybody else wants one (less than other places): http://www.ebay.com/itm/230984113188?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

I take the Toby word for gold, so I guess I'll man up and tap #2 & 3 underneath. Do you know if a vacuum reserve canister is still necessary? Does the anti-pulse valve become overkill in this scenario?

 

how's this:

 

--- represents hose.

 

(Runner #2) fitting ----

                                    Tee fitting --- anti-pulse vale ---- vacuum reserve canister---- distributor (123tune)

(Runner #3) fitting ----

 

 

I think I might also need some fittings to compensated for the different sizes?

 

Edited January 26, 2017 by MildSeven

[Harv]

Going the 4 hole route would only be advisable with DCOEs or ITBs. If your using a single carb, only one take off is used. 

 

John

[MildSeven]

43 minutes ago, Harv said:

Going the 4 hole route would only be advisable with DCOEs or ITBs. If your using a single carb, only one take off is used. 

 

John

 

yes, I have dual DCOEs

[Simeon]

I would check with a mechanical vacuum gauge what you are actually getting as well as the 'gauge' on the 123. Depending upon how quickly the 123 reacts to changes you may just see a lower overall vacuum signal which you could potentially tune out. If the MAP pressure is shown to be all over the place then you need to get to more intake runners. 

[MildSeven]

Ok, so I think I'm going to tap all 4 runners, underneath....since the resident experts are saying 4 is better than 1. My car in under a tarp in the corner of the garage for the winter.. but I'd like to prep for spring.

 

Any advice on the piping setup? and especially any suggestions for shops to buy the fittings/connectors... having problems with google and 3.5mm stuff.

 

Here's a mock up (I made), to show you guys for your advice/feedback.

 

 

 

Getting a shopping list together.

4x 3.5mm barb / 1/8 NPT thread - elbow

1x 3.5mm barb / 3.5mm barb - elbow

3x 3.5mm - Tee

3.5mm ID hose

1x anti-pulse valve (purchased already)

18x spring clamps

...also possible a tee with a vac gauge.

 

as always.. THANKS SO MUCH!

Anthony

 

 

 

 

 

 

 

Edited February 3, 2017 by MildSeven

[TobyB]

The problem with what you've drawn is that it will 'leak' to #4 (or what ever is last in line)

 

I think Simeon's advice is good- see how much damping and/or conditioning there is in the 123.

(and- gasp- ask THEM what they recommend!  It would not be difficult to electronically buffer

the pressure sensor to read peak vacuum on a runner, and ignore the leakage.)

 

Thinking about it, vacuum advance is most useful at small throttle openings,

so very small restrictors on all 4 ports (like, solder your npt- hosebarb adaptors shut,

and then drill them out very small) might work best.  The system will be in a constant state

of leak, but maybe it will provide a useful signal for tuning.

 

The OE systems (Alfa, in particular) use 4 equal- length tubes that all land on

a reservoir, and then the distributor reads reservoir pressure.

 

I think, if 123 doesn't already have the answer for you,that this will turn into a science experiment!

 

t