PorKen-ized my vacuum system!
05-01-2004, 01:54 PM
#1
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Join Date: Jun 2001
Location: Ashburn, VA
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PorKen-ized my vacuum system!
PorKen,
Just wanted to give you some feedback. I did a top-end hose/gasket replacement and figured I'd do a little modification work on the vacuum system. My only vacuum systems left are: Ported vacuum (side of throttle body facing the rear) to pressure regulators/dampers. Ported vacuum to distributor advance. Manifold vacuum to brake booster and A/C system. Sound right?
It's running rather nice right now. Much more instaneous acceleration (as you called it, 'snap acceleration'). Hit the pedal and feel it instantly. No more sucking air from the various miles of vacuum hoses before the AFM starts moving.
I'm going to measure the vacuum sometime soon. What readings should I expect with a cat bypass?
Luckily my low yearly mileage exempts me from any emissions requirements =)
Just wanted to give you some feedback. I did a top-end hose/gasket replacement and figured I'd do a little modification work on the vacuum system. My only vacuum systems left are: Ported vacuum (side of throttle body facing the rear) to pressure regulators/dampers. Ported vacuum to distributor advance. Manifold vacuum to brake booster and A/C system. Sound right?
It's running rather nice right now. Much more instaneous acceleration (as you called it, 'snap acceleration'). Hit the pedal and feel it instantly. No more sucking air from the various miles of vacuum hoses before the AFM starts moving.
I'm going to measure the vacuum sometime soon. What readings should I expect with a cat bypass?
Luckily my low yearly mileage exempts me from any emissions requirements =)
05-01-2004, 02:24 PM
#2
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"PorKen-ized". I'm not sure if that's complimentary. 
"Ported vacuum (side of throttle body facing the rear) to pressure regulators/dampers. Ported vacuum to distributor advance. Manifold vacuum to brake booster and A/C system. Sound right?" Yes, very good, grasshopper.
The vacuum level will depend on your ignition (and valve) timing, but if I remember correctly, I had around 19" mercury at idle after doing the vacuum simplification, with a few degrees ignition advance over stock, and before I messed with the valve timing.
BTW: After doing the exhaust work, you may not feel the full potential unless you up the fuel pressure a little.
Thanks for the feedback!
"Ported vacuum (side of throttle body facing the rear) to pressure regulators/dampers. Ported vacuum to distributor advance. Manifold vacuum to brake booster and A/C system. Sound right?" Yes, very good, grasshopper.
The vacuum level will depend on your ignition (and valve) timing, but if I remember correctly, I had around 19" mercury at idle after doing the vacuum simplification, with a few degrees ignition advance over stock, and before I messed with the valve timing.
BTW: After doing the exhaust work, you may not feel the full potential unless you up the fuel pressure a little.
Thanks for the feedback!
05-01-2004, 03:34 PM
#3
18-21" sticks in my mind as the range; the higher side being accomplished soft-cammed torque tuned v-8s (like 440 cu in motor home engines), so anything in that range should be fine.
