Carburetor E85 Equalizer GM 604 Crate

The Carburetor E85 Equalizer GM 604 Crate from WILLYS CARB is a purpose-built fuel metering system engineered for high-performance crate engine applications demanding flex-fuel compatibility. This model-4150 four-barrel carburetor delivers 750 CFM of airflow capacity and is specifically calibrated for the GM 604 crate engine platform, a popular choice in racing, off-road, and performance vehicle builds. The E85 Equalizer designation signals factory tuning for ethanol-blend fuel (up to 85% ethanol content), which requires precise jetting and calibration to maintain optimal air-fuel ratios and prevent lean-running conditions that damage engines.

Constructed from aluminum with a professional-grade black powder coat and red anodized finish, this carburetor features mechanical secondary activation, dual inlet ports for balanced fuel distribution, and a square-bore design that maximizes runner flow. The no-choke configuration eliminates cold-start complexity and is standard on carburetors intended for warm-climate or dyno-tuned applications where manual or electronic choke systems are unnecessary. Weighing 10.21 lbs and measuring 11 x 9 x 13 inches, the unit is compact enough for tight engine bay installations while maintaining the internal volume required for stable idle and transition circuits. The mechanical secondary design ensures progressive throttle response—secondary barrels open only as primary demand increases, preventing fuel waste at part throttle and improving drivability.

This carburetor is ideal for serious performance builders, drag racers, and enthusiasts running E85 fuel in GM 604 crate engine platforms who demand precision fuel metering without computer-controlled complexity. Direct bolt-on compatibility with dual-inlet fuel systems makes installation straightforward on pre-configured crate engine blocks. Buyers should verify fuel-line sizing, bowl vent routing, and air-filter adapter fit before installation; E85 operation requires stainless steel or compatible fuel system components to prevent corrosion. Professional tuning and baseline jetting verification at a dyno facility are strongly recommended to optimize performance and ensure the engine receives correct fuel mixture across all load ranges.