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View Full Version : "Safe" de-vacuuming?



Soundy
10-03-2005, 10:03 AM
I wouldn't mind trying some of the "de-vacuuming" performance boosts on my G3, but we do have yearly emissions tests here to worry about...

I'm wondering if instead of removing all those vacuum lines, I can get away with just pinching off most of them, and rerouting as few as possible, so it can be "put back" when test time rolls around? Anyone have a procedure for this?

This is pretty bare engine, very few take-offs - no A/C, no P/S, 5-speed (so no auto tranny interface) - basic Keihin 2bbl, 2.0l, etc... haven't actually looked at whether it's auto-secondary yet...
:dunno:

HondaBoy
10-03-2005, 12:25 PM
the problem with doing a vacuum removal in that maner is that it will get pretty confusing. and if you do actually reroute the vacuum lines correctly, you will likely have a hell of a time getting them put back so its running lowered emissions. i'd say if your going to have emissions tests, dont even think about doing a vacuum line removal! sometimes i wish i hadnt done it on my car, but to tell you the truth i dont believe it was working correctly the way it was. a thing i'd recommend is doing a manual secondary opener. you'll find the way to do that in the how to section. that's one of the most simple and worth while mods you can do that wont get you into trouble. with the manual opening secondary, you dont have to wait until your engine pulls enough vacuum to open the secondary by the puller diaphram. in many cases its deteriorated so it doesnt open at the right time or sometimes not at all. but yeah, i'd say definately go for the manual secondary. dont know if you'll be able to do it though since you have no A/C. you use a part from the A/C idle boost diaphram's mechanical crap. if you dont have that i'd say go look at a junk yard for one.

A20A1
10-03-2005, 01:27 PM
The whole idea around the vacuum removal is to get rid of any unreliable vacuum operated component. Everything gets old and deteriorates. Too much to keep up with to maintain performance.

If you could find large enough vacuum caps or check valves you could effectively block any vacuum signals from bleeding from the intake manifold. Then selectivly reconnect the ones you need to the rear of the intake manifold.

There are 4 main vacuum taps on the intake manifold, you have to remove the vacuum lines to get to them and plug them. You wont be removing the vacuum lines really, you'll just cut them off from the intake manifold.

Vacuum lines needed:
- Choke (#17 , #18 , #19)
- Ignition Advance (#2)
- Powervalve (#14)
- Air Jet (ABC)

Things will get complex, and it wont be easy for me to explain so you're pretty much on your own.
Honestly the best you can do is what you've done already... getting rid of the extra components, cruise control, A/C, powersteering.

The secondary it part vacuum part mechanical secondary. You can convert to mechanical secondary if you want. I had to file down the linkage on my carb to get a smoother opening to the secondary. I notticed when I first did the mod there was some binding in the linkage... even though both barrels closed it could possibly cause the throttle to stick, so filing down the linkage really helped. I'll post pics when I get home.