Acertain chevy 350 engine in one of our old project trucks started having issues that seemed to be pointing to the carburetor as a culprit. On cold start-ups the truck would idle high like it should but then it wouldn't return to a normal idle no matter what we tried. It would also hesitate when trying to quickly accelerate and occasionally sputter and die when off-road in off-camber situations. Vacuum leaks were searched for and different adjustments were attempted but nothing seemed to help. While it is possible that the old Quadrajet carb could have been revived, we decided to simply upgrade it hoping for better drivability, performance and reliability.
Due to the type of engine, and the fact that the truck was a '74 with little emissions requirements, there was a huge selection of carbs to choose from. We decided to call the crew at Holley, with their great reputation, and see what type they recommended for our application. It turns out the choice was quite easy. Holley makes a line dubbed Off-Road Truck Avenger Carburetors, which are made especially for off-road conditions. These carbs offer a slew of features that make adjustability and reliability paramount even in harsh environments. To complement the carb, we also chose an aluminum Weiand Street Warrior Intake Manifold. The dual-plane design has a power band from idle to 5500 rpm and will help our old 350 breathe easier.
Holley insists in its installation instructions that the carburetor is wet-flowed and preset at the factory to fit most applications without any adjustment. We were pleased to find that Holley was right in our case. After a few cranks to get fuel into the new carburetors bowls, the truck started right up. Then, after a short drive, the choke turned off and the idle dropped down to where it should. Throttle response was much improved at lower rpm's in addition. It is possible that we could see even better performance with some fine tuning but for now we will continue to use the carb as it came out of the box.