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MikeDanger · Joined: 21 Nov 2002 Posts: 774 Location: Denver

well since im installing my own EFI/ignition, do i need to keep any of the vac lines? im not even sure where they go at thi point any way, im not using the stock TB (but i havent gotten the new one yet) so im not sure if there is any line to it, but it seems like the stock stuff is a mess, should i just rip it all out?
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It was either this or a giant box of legos

macBdog · Posted: Wed Sep 28, 2005 7:12 am Post subject:

You still need vacuum to the brake booster as well as manifold pressure to your ECU. Depending on your ECU you may also want to keep the decel valve... maybe WUR etc. Can you tell me a bit more about your setup? I'm about to take the plunge with megasquirt.
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1979 931 with a 350 chev
1973 911E with EFI

leadfoot · Posted: Wed Sep 28, 2005 8:07 am Post subject:

Yep rip it out and start fresh..... lines probably 20 years old anyway
You may want to simplify things and just bolt a vaccum resevoir to the back of the manifold and plumb from there as opposd to T fitting different lines.

You will need from stock setup...
Brake booster vaccum
EEC valve vaccum (vents gas tank and emmissions from charcoal cannister)

Extra you might need or want
ECU line for MAP vac/boost
Vaccum/Boost gauge in console
Fuel regulator vac/boost

Also you might consider a boost solenoid and an idle control solenoid which will both need different air lines to and from them, but shouldn't need a control vac/boost line.
Leadfoot
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

MikeDanger · Joined: 21 Nov 2002 Posts: 774 Location: Denver

ok , stupid question, where do they originate from?
do the large lines go/come from a different place?
Decel valve? which is that? This is a modern EFI system i dont think it has/needs that
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It was either this or a giant box of legos

MikeDanger · Joined: 21 Nov 2002 Posts: 774 Location: Denver

leadfoot · Posted: Wed Sep 28, 2005 7:00 pm Post subject:

As I said... rip it out and start fresh...
think of it like this....
my brake booster has a 5/8 hose and it needs vaccum only...therefore I need to plumb it into the manifold or pipes post throttle or after throttle plates to a suitable position. Now suitable position may mean either ctreating your own or using a fitting allready there. Understand the nature of the vaccum your supplying in the case of the brake booster will not tolerat have any boost supplied to it and will need a checkvalve placed inline (or in the line) of the hosing. The check valve allows the vaccum of the manifold to be sucked down the line and from the brake booster to assist braking (good) whilst shutting and preventing boost form being applied to it when the flow is in the other direction (bad).
Make sense...
Here's another example....
ECU has a MAP sensor that requires vac and boost.... well then you know that it should come from the manifold post throttle again.... Hmmm I here you saying why post throttle, well it's a question of where vaccum is created at its greatest. After accelerating on open throttle and lifting of the pedal the throotle plates close and the engine creates alot of vaccum as its sucking in a closed environment (the manifold).
So you can get a barb fitting and tap the manifold to obtain your own source for the tubing, or use one of the rubber hoses and a T fitting with the appropriate size diameter, you can find these at any auto supply store in brass and sometimes plastic (brass is better though.
So then you create your own lines and block any off you don't require....
I suggest you buy a book on EFI systems before you go playing around in your engine though. It will help you with more than the vaccum diagrams.
Leadfoot
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

MikeDanger · Joined: 21 Nov 2002 Posts: 774 Location: Denver

ok on the intake manifold there is a 5/8 line on the bottom side of the large "collector" after the TB and before the runners, will that work to start from?i believe this went to the warm up valve and some gold vacuum thing
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It was either this or a giant box of legos

leadfoot · Posted: Thu Sep 29, 2005 5:39 pm Post subject:

Yep, fine to take it from there...
You might also consider at the rear of the manifold near the firewall as it is lees like to be in the way of throttle etc and also be a more central position to run the lines out from.
Leadfoot
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...