Standard bore LCB (1-3/4"id) that is ideal for very hot small bore engines, for standard to high performance 1275s, and for street 1380s. The best quality production manifold is made by Maniflow. The Long Center Branch design has been proven to be the best all-around for our 5 port cylinder heads. Bore diameter being the only other variable.
For fuel injected (not carb), catalyst cars (approx. post 1992) when the catalyst is removed to fit an RC40 complete system. Has the sensor take off.