This carb is installed on a mildly modified 455 that idles a bit roughly (need to set idle to 800) and at WOT passing through 3,500rpm where it'll stumble badly. It'll recover quickly if I just back off a tiny bit. If I accelerate with just slightly less than WOT I get no stumble and the engine will run up to redline. Plugs look slightly rich. Fuel pump is an aftermarket high-capacity Holley and the filter is clear but it seems to me that I have a fuel delivery issue. The rest of the fuel system is stock. Ideas?
Also, just out of curiosity, I noticed a vacuum port that I haven't seen on any other Quadrajets. It's where the idle compensator (or cover plate) would go right above the rear throttle plate manifold vacuum port. I'm pretty sure those carbs with dual choke pull-offs use a dedicated port in the throttle plate (which this doesn't have) but what would it be used for? (It's capped right now)
