I tried what you said and it's no better. By the way I unhooked both the rods that connect the vacuum pulloffs to the carb to totally eliminate that. I do have a temporary manual choke I control from inside the cab just so I know for sure what the choke is doing. What do you have your primary rod height set to? I want to know so I can adjust mine the same. When I do go to wot it will bog but if I let off a little the truck seems to get back to normal.
Thanks,
duly
Ok, so your choke pulloff(s) are disabled, the secondary air valve should function normally once the primary throttle position drops out the interlock and allows secondary operation.
As for the setting for the primary metering rod height, I usually don't have to deviate from the initial setting described in the assembly guide. Now I'd go out and spend time playing with that making two turns at a time. After each adjustment, test drive and determine "better" or "worse" or "no change".
Also, tighten the secondary air valve spring by one turn at a time and test drive that.
We're trying to determine if this is a "tuning" issue or a problem with restricted fuel (or metered air) in a carb circuit.
Your description leads me to think there May be a fuel delivery issue and when the secondaries are open, the engine is leaning out. Make certain the float levels are set correctly, that your fuel pump and fuel tank system are clean and delivering sufficient volume/pressure at high rpm (I've had this exact issue occur on chev motorhomes with a quadrajet which was due to inadequate fuel delivery due to a "weak" fuel pump and three clogged fuel filters!!!!).
When you went through the carb, did you very carefully clean out those tiny calibrated orifices in the air bleed tubes (brass) and also clean /verify all the calibrated orifices where you see "brass" from the top/outside of the fuel bowl cover??? I use a welding tip cleaner very carefully to clean and trace every orifice, carb cleaner will not break down any corrosion that will be inside those tubes.
When you remove the secondary metering jets (the long brass tubes), the air bleeds are inside. I remove those from the carb top for cleaning, but I'd caution ya against doing so and simply clean with 'em installed. Atmospheric pressure must enter the top of that tiny brass tube at the top where that bleed tube is pressed into the carb top....very tedious!
One last thing, this is a shot in the dark...
A typical kit includes at least two, sometimes three pair of "o" rings that seal the secondary jets into that problematic area of the fuel bowl that we have to do the repair with epoxy. You will find they are three different cross-sectional thicknesses. One pair is actually an "x" shape in cross section! Those jets must seal tightly down in that well, otherwise raw fuel is metered around the calibration instead of through the calibration! So pick the pair of seals that allows a tight seal when the bowl cover screws are tightened!
