With its 90cc volume, the smog-era 452 head has the largest chamber of any open-chamber ('68-up) OE big-block head, but it's nothing a 0.010 deck cut won't cure. Because these heads lived on a hardworking motorhome the Magnaflux inspection process was given extra scrutiny, but no flaws were found. Though factory-equipped with induction-hardened valve seats, new hardened inserts were installed to restore valve height and then given a three-angle cut. About six hours were spent opening the bowl areas with a hand grinder. Superior's cylinder head guru, Fred Simpson, handled all head work. With its 90cc volume, the smog-era 452 head has the largest chamber of any open-chamber (' The magic of the A&A 440 port manifold is its smaller intake-runner openings, as highlighted by this comparison with a stock Max Wedge intake gasket. But Rick Allison also reduced and massaged the runner sizes inside the manifold to match. This strategy keeps the intake charge moving (high port velocity), a detail that increases its inertia and further enhances the ram effect. This manifold is not recommended for big-displacement stroker applications where it may limit upper-rpm breathing potential. Fear not: A&A also sells an original-size big-port Max Wedge cross-ram (and magnesium Race Hemi cross-rams) for all-out efforts where original appearance is desired. The magic of the A&A 440 port manifold is its smaller intake-runner openings, as highlight The tired two-piece 2.08/1.74 Chrysler valves were replaced with one-piece Milodon forged stainless valves. The smooth faces add a little weight but reduce total chamber volume for added compression. The Chrysler intake and exhaust valves weigh 136.2/111.1 grams compared to the 139.8/126.5 grams of the stainless valves. At Daytona they might care, but it's a nonissue in this case. The tired two-piece 2.08/1.74 Chrysler valves were replaced with one-piece Milodon forged Head gaskets are always part of the compression equation. The 252cc 1-inch-down cylinder volume, 86cc postmilling chamber volume, and 0.039-inch-thick Fel-Pro composite gasket (bottom) yield a calculated 9.75:1 compression ratio. If we substitute the 0.015-inch-thick P4286754 MP steel shim head gasket (top), compression rises to a calculated 10.4:1. We'd love the added cylinder pressure but refuse to be slaves to race gas or additives in 91-octane California. So we'll go with the thick gaskets on this all-iron mill for pump-gas compatibility. Head gaskets are always part of the compression equation. The 252cc 1-inch-down cylinder v With minor pocket porting, Simpson increased intake port flow an average of 24.9 cfm, with maximum numbers growing from 224 (stock) to 253 cfm at 0.600 lift, proving a little goes a long way when it comes to Chrysler big-block head modifications. On the exhaust side, flow increased an average of 32.5 cfm with peak numbers rising from 151 to 193 cfm at 0.650 lift. With minor pocket porting, Simpson increased intake port flow an average of 24.9 cfm, with Our hydraulic cam allows use of inexpensive 1.5:1-ratio, OE, stamped-steel rocker arms. They aren't sexy but are proven stable at 6,500 rpm thanks to their 129.4-gram light weight and rugged design. For extra reliability we junked the used motorhome parts and went with new MP replacements for $82. Isky 31/48-inch-diameter adjustable chrome-moly pushrods allow gnat's-ass hydraulic lifter preload settings and compensate for deck and head material removal. Our hydraulic cam allows use of inexpensive 1.5:1-ratio, OE, stamped-steel rocker arms. Th The A&A cast-aluminum cross-ram is a masterpiece of American craftsmanship. A virtual replica of the original Max Wedge item but with smaller port openings, it weighs 38.1 pounds bare. Like the original, the 15-inch-long tapered runners feed cylinders on opposite sides of the engine. The tuned runner length takes advantage of the naturally occurring pressure waves within the intake tract as the valves open and close. Chrysler's Tom Hoover and his staff originally designed the runners to deliver the maximum punch of the pressure waves-which travel at the speed of sound-to the backs of the intake valves between 4,500 and 6,000 rpm. The result is volumetric efficiency in excess of 100 percent within this rpm window. Put in basic terms, it amounts to free supercharging. The machined aluminum plugs seal the exhaust-heat crossover passages found on regular (non-Max) wedge heads like our 452's. The A&A cast-aluminum cross-ram is a masterpiece of American craftsmanship. A virtual repl « | 1 | 2 | 3 | 4 | 5 | » | View Full Article Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!