IMCA has introduced a new spec engine option for 2025, set to be legal for competition starting January 1. This engine can be built from a 604 crate short block or from scratch, using parts familiar to drivers and builders. Required components include EngineQuest or DART cylinder heads and Edelbrock intake manifolds. The spec engine will be compatible with the 604 crate’s valve spring rule.
Both the spec and crate engines will feature a maximum 6,800 rpm rev limiter and may use the same carb adapter. A two-inch rear spoiler is allowed, but neither engine can be claimed. The new spec engine offers a cost-effective, competitive alternative to the crate engine, combining performance similar to the 604 with some characteristics of a claim motor.
Drivers must indicate their engine choice on the driver’s side roof post. IMCA aims for a balance of affordability and competitiveness with this option.
