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Old 03-23-2010, 05:55 PM
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AVS carb adjustment

Any of you guys got one of these mechanical/vacuum secondary carbs? Been doing some adjustment,tuning, and trying to find a happy place where that door opens without slamming shut almost instantly. Then if I turn the spring one nano less tension it opens to easy totally negating its benefits. With something that hairy I struggle to believe that little spring is going to stay in that magic spot of tension should I happen to find it

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Old 04-20-2010, 09:38 AM
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ADJUSTING THE AIR VALVE SECONDARY
1. With Torx drive (T15) and flat blade screw driver in place, loosen
Torx screw, make sure flat blade is secure to prevent loss of spring
pressure.
2. If you lose spring pressure, turn flat blade screw counter-clockwise
until the air valve reaches closed position plus 1-1/2 turns to
achieve the factory setting.
NOTE: Turn only 1 full turn beyond closed position for
1803/1804 factory setting. For single carb applications, set
1803/1804 carburetors to 1-1/2 turns past closed position.
3. The factory setting is the most common setting. If additional tuning
is required, turn the air valve screw counter-clockwise to make the
air valve open later, it is not recommend to go beyond one turn more
than the factory setting, or more than 2-1/2 turns past the closed
position.
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Old 04-20-2010, 09:48 AM
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Quote:
Originally Posted by sooper
trying to find a happy place where that door opens without slamming shut almost instantly.
Are you saying the secondary air valve opens, then slams shut, while you're still at WOT?
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Old 04-20-2010, 09:50 AM
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Sounds like he is trying to make them open while in park, You can't do that.
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Old 04-20-2010, 11:07 AM
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Quote:
Originally Posted by Denny
Sounds like he is trying to make them open while in park, You can't do that.
That's true- if they're opening w/o a load on the engine, they'll open WAY too soon on the road...
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Old 05-14-2010, 06:53 PM
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Quote:
Originally Posted by cobalt327
Are you saying the secondary air valve opens, then slams shut, while you're still at WOT?
Sorry for the late reply. Got onto other things. Yes thats what I'm saying. Breather off,hood off,watching at WOT. Flies open for 1/2 second or so then shut. I keep lightening spring tension but not much difference in results. I'm soon going to crank the thing right open and use it as a straight mechanical 650 CFM
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Old 05-14-2010, 08:26 PM
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Quote:
Originally Posted by sooper
I'm soon going to crank the thing right open and use it as a straight mechanical 650 CFM
Out on the open road, you ain't gonna like the results of doing that, I can assure you.

Tune the secondary opening w/the engine under a load. Safely. No other vehicles/pedestrians, pets.

Trying to tune the secondaries by jazzing the throttle in neutral/park will not be any indication of how it will behave under a load. If it opens up in neutral, it will bog in real world driving, because it will be opening too soon.
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Old 05-15-2010, 04:48 AM
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[QUOTE=cobalt327]

Trying to tune the secondaries by jazzing the throttle in neutral/park will not be any indication of how it will behave under a loadQUOTE]

exactly.

i,ve always tested on road
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Old 05-15-2010, 06:02 AM
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Quote:
Originally Posted by sooper
Sorry for the late reply. Got onto other things. Yes thats what I'm saying. Breather off,hood off,watching at WOT. Flies open for 1/2 second or so then shut. I keep lightening spring tension but not much difference in results. I'm soon going to crank the thing right open and use it as a straight mechanical 650 CFM
As cobalt explained, you can not adjust the secondaries in that way and expect it to be drivable (perform like it is designed).
You can not run it as a mechanical 4bbl either, there is no squirter to help with the transfer from idle to part throttle unless you way over compensate with the primary squirter and again the carb is not designed for this and it will not be performing as it could.
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