The early ThermoQuads started out in very basic dress, with numerous add-ons coming into play later in production. The throttle stop solenoids or the TPS used on ESC cars are examples, though these devices are not a part of the metering function of the carb. Some later carbs came with a solenoid activated bowl vent, and if your carb is so equipped it has to be hooked up and functioning for the carb to fuel. This device can be defeated by removing the seal.
Up front the later TQ's featured a flat-faced boss on the airhorn. Carbs of this configuration were revised with an auxiliary air bleed circuit that affects the fuel mixture. On some carb variations, this front boss was left un-machined and blank, defeating the additional air bleed circuit. Chrysler used three variations of controls on this air bleed provision, most commonly a vacuum operated diaphragm that closed the air bleed to enrich the mixture during warm up. Some carbs added a high altitude compensator valve to the enrichment diaphragm assembly. Our carb is so equipped. Finally, later OEM TQ's utilized a feedback solenoid here to electronically alter the metering via a primitive ECU feedback system.
For the price of a 25-dollar core and a parts store carb kit, we had a healthy 850 CFM mixer perched atop our potent small block. While that might seem like a lot of carb, the TQ's unique metering and fuel delivery systems allow it to defy the normally accepted rules of carb sizing, even in much lower-powered OEM applications. With that level of flow on tap, we know the capacity is there to feed whatever our engine might demand. With the TQ's three-stage metering rods and small primary barrels featuring dual-booster venturi, we also know the TQ can be tuned to unrivaled carburetor efficiency. Best of all, we can look forward to laying those huge secondary butterflies on end, and hearing that signature ThermoQuad sound, with a throaty roar that leaves passersby asking, What the… was that?"