The foundation for the 604 IMCA Crate Motor is the Fast Burn Engine. With four bolt mains, high strength pistons, durable iron block and performance pistons, the CT400 is tuned for power! Today’s 604 IMCA A-Mod/Modified Crate Engine (P/N 19318604) comes available with or without an IMCA-seal from the factory. Eight bolts in key locations make tampering with the engine unlikely without destroying or damaging the bolt head.
The rest of the package includes a single-plate aluminum high-rise intake manifold, special roller rocker arms a valve cover breather kit and balancer. You choose your carburetor, spark plugs and wires, distributor and your off an running. This Chevy Performance 604 IMCA Crate Motor is tuned for more power, producing 404 horses and 406 lb.-ft. of torque under peak conditions.
Key components included as part of the engine package are Fast Burn cylinder heads with LS-style beehive valve springs that provide greater durability and high-rpm performance. The open-plenum high-rise intake manifold is designed to use a standard flange Holley carburetor. The rocker covers have center hold-down bolts. (The left has two 1-3/8” tall tubes and two baffles; the right is stamped without holes.) Aluminum roller tip rocker arms are self-aligning style with a full roller design. The oil pan, designed for circle track racing, will clear most GM rear-steer chassis with stock engine location. It has an eight-quart capacity and is 7 inches deep, with a dual kick out design.
Chevrolet recommends the HEI distributor (P/N 93440806) which is properly curved for this application, and comes with a melonized drive gear. Also recommended for the CT400 is the model 4150 HP, 650-cfm Holley four-barrel carburetor (P/N 19170097). An finally, to keep your engine operating temperature between 180° and 200° F, two water pumps are recommended, depending on the application. The long leg cast iron pump is P/N 88894341; the short leg cast iron version is P/N 12458924.
Available from Karl Performance Parts, of course – and you will be ready for the starting line. We give you the machinery. The rest is up to you!