Both the elegant design and the simplicity in the maintenance of the WEBER Carburetors have proven to be compelling reasons as to why the Weber name has remained so popular over the years.
The Weber 51 IDA carburetor is a special Racing Beat modification to a standard 48 IDA unit. This extensive modification involves machining the main body for larger throttle plates, fitting larger aluminum air horns, changing the needle valve, emulsion tubes, venturis, main jets, and air jets to work more effectively on the 13B peripheral port engine. As an alternate to the K&N Air Filter Assembly Kit, we supply an information sheet detailing our recommendations for the design of a cold air box.
While the Racing Beat-modified 51 IDA Carburetor is intended for use on 1974-85 12A & 1974-85 13B 4-Port engines, as delivered, the Racing Beat-modified 51 IDA carburetor is tuned for a 13B peripheral port engine.
The Weber carburetor is well suited for various race applications because of its simplicity, compactness, tunability and excellent float bowl design. As applied to a rotary engine, the carburetor exhibits a variety of good characteristics. However, in a stock or street-ported engine this carburetor's lack of a choke system makes it very cold-blooded, even in warm climates.
The Weber 51 IDA carburetor is also suitable for use on a number of rotary engine applications, including a 13B bridge or J-bridge ported engine, or the 12A peripheral ported engine. If the 51 IDA carb is intended for use on these engines; we offer the appropriate Weber components to properly tune the carb for these applications. Follow this link for a listing of tuning recommendations for various rotary engine applications. (PDF)
However, the one application where the Weber 51 IDA carburetor performs best is on a peripheral ported 13B engine. Here, its relatively small size is compensated by the excellent breathing capability of the porting on the engine. Although the 48 IDA carb can be used on a 12A peripheral port engine, power can be increased by approximately 10+HP if an upgrade is made to the 51 IDA unit!
The selection of an appropriate intake system requires that many factors be taken into consideration. Various intake systems yield different performance characteristics based upon specific engine, exhaust and driveline selections. Due to the complexities associated with these configurations, it is difficult to determine exact power gains for specific applications. Use this intake reference guide (PDF) for performance comparisons between the Weber and Holley Intake systems that we offer.