Here’s a regular production Max Wedge engine bay as seen in a 1964 Plymouth Fury. Compared to a contemporary Chevy 409, Ford 427 or Pontiac 421, we’d bet these things sold on looks alone!
This comparison shot illustrates the crux of the Max Wedge plan – intake (and exhaust) ports some 25 percent larger than stock. The bottom casting is a 1964 vintage Stage III Max Wedge #518 casting. The little guy on top is a 1978 vintage 452 casting. It shares general port configuration with 906, 346 and 915 wedge head castings. Notice the arched exhaust heat crossover port on the stock casting. The Max Wedge eliminated the exhaust heat crossover feature to keep intake charge temperature as low – and dense - as possible. While the Max Wedge shares 2.08 intake valve diameters with most regular wedge heads made after 1967, the Maxie upped exhaust valve size from 1.74 to 1.88 inches for extra exhaling potential.
Here’s a comparison of a 1963 vintage Stage II cross ram (on left) and the new Mopar Performance P5007330 reproduction on the right. Initial observation shows nearly identical appearance but the MP unit is claimed to be capable of a 20-percent flow increase. Priced at $1660.39 plus $195.39 for the fastener kit (PN 5153338), the new MP cross ram casting has extra runner and plenum volume and is likely a better choice on a stroked 500 inch Max Wedge than an original type casting when maximum power is preferred over original looks. The MP casting accepts vintage stock or reproduction bell crank assemblies and related throttle linkage. This stuff is readily available from A&A Transmission and Kramer Automotive Specialties.
 The MP cross ram is more angular and does have some added dips and valleys, particularly by the sides of the carburetors. These rectangular depressions were added to clear the low hanging carburetor linkage used on modern Edelbrock Performer type carburetors. |
 For contrast, the vintage Max Wedge casting is a familiar sight to those used to studying vintage magazine photos. Many used manifolds show up minus the individual throttle bores. It used to be popular to machine the area to remove the individual holes. Max Wedge veterans claim this modification adds top end breathing but with a small penalty in low end torque. We’ve tried both and haven’t noticed any real difference either way. If you run Edelbrock carbs on one of these, you’ll need to trim the bottoms of the throttle levers to keep them from hitting the top of the plenum. It isn’t a big deal and takes a few minutes. |