From Stock Commission:
B, 20 & 25 Class participants,
This change has been approved by the 2012 B, 20 & 25 Class Parity Committees and will be effective 30 days after appearing on this website. (September 8, 2012)
15H & 20S:
The 15H & 20S Sidewinder engine competing in the APBA “B, 20 & 25” classes is being supplied with an updated carburetor adapter. The new adapter reduces the engines sensitivity to the location of the spray shield. The adapter has the same internal dimensions as the original part but has a boss that extends into the intake manifold. The boss helps maintain intake velocity, improving fuel distribution to the cylinders at low and mid speeds and during wide-open throttle, high load (low RPM) conditions.