V-Boost "Blahs"

[Eazrider]

Some time back, I had my 85' Max apart to replace low gear, and to install a Venture 5th (overdrive ratio) while I was in the tranny. Now, I find that as I accelerate through the gears, at the point (about 7000 rpm or so) where it used to rip my arms out of their sockets, it seems to go flat and sort of drone on to higher rpms. It still revs out, just not hard. I have checked the V -Boost, by revving the engine and watching the cable/acuator open the V-Boost valve.Before I pulled the engine, it ran like a raped ape, it just had issues with low gear. Typically,I still get the same gas mileage as before around town...30-35 mpg...any ideas....?

 

[shawn kloker]

Synchronize the carbs and look for any air leaks in the carb,airbox and vboost boots.

 

[Eazrider]

I syncronized the carbs, they were a bit off. When at wide open throttle, carb sync doesn't enter into the equation, as all of the carbs are wide open. After re-syncing, I noticed the vacumn line attached to the left front cylinder had an arrow on it: can you identify what this vacumn line is attached to on the other end from the manifold? If this was installed backwards (a possibly..!) what would the result be..? The V-Boost valves are opening, I can confirm visibly (revving the throttle) and they can be felt when accellerating. Right after it really starts pulling hard is when it seems to get the "blahs".....

 

[maleko89]

That goes to the vacuum sensor which is used by the ignition to determine amount of supplemental ignition advance. If it's not working correctly it wouldn't run very good at higher vacuum throttle settings.

Mark
#1098

 

[Eazrider]

That goes to the vacuum sensor which is used by the ignition to determine amount of supplemental ignition advance. If it's not working correctly it wouldn't run very good at higher vacuum throttle settings.

Mark
#1098

Which way is the arrow on the little 1 way valve supposed to point? Manifold or ignition advance module...?

 

[maleko89]

To the pressure sensor, not the manifold.

Mark
#1098