Under these circumstances, swapping the cam and cylinder heads together was the most realistic combination. The Edelbrock heads require stud-mounted rockers and are designed to accept any aftermarket Chevy rocker arms for 3/8-inch studs. To fulfill this requirement, we went with a set of Comp 1.6:1-ratio aluminum roller rockers. Because replacing the pedestal OEM Magnum rockers requires hardened pushrods to work with the Edelbrock heads' guideplates, we finished the valvetrain package with a set of Comp Magnum pushrods.
The final item in our combination to be changed was the two-plane M1 intake. Clearly designed more for low-end torque than horsepower aspirations, this intake manifold is wholly out of place with our cam-and-head combination. The solution here was the Mopar Performance M1 single-plane intake, a long-runner manifold that has proven to make good top-end power while retaining high levels of torque through the midrange. In fact, this is the intake design Mopar Performance runs on all of its higher-output crate engines. With that, we had our Magnum power package-the Comp rockers, pushrods and XFI cam, Edelbrock heads, and Mopar single-plane intake. Each of these components substantially raises the bar on the hardware they replace.
With the jetting dialed in, the power pulls confirmed that this parts selection put major firepower in the basic Magnum package, with 448 hp recorded at 5,800 rpm and 435 lb-ft of torque coming to bear at 4,900 rpm. The cam, heads, intake, and valvetrain package was worth a staggering 129 hp on the stock Magnum mill. For us, that is a righteous gain for a well-selected assortment of out-of-the-box aftermarket parts on a stock production engine. Far from a raucous and unruly combination, the modified engine idled easily at 850 rpm with 12 in-Hg of manifold vacuum, a level that is right at home in a street-driven machine. With output like this ready for the taking, it might be worth considering giving Magnum power a home in your Mopar machine.
Mopar Engine hooked up to the dyno ready for testing. | 
Stock Magnums utilize pedestal-mount rockers, a departure from the traditional Mopar shaft systems. Most aftermarket kits convert these nonadjustable rockers to a stud-mounted system that accepts Chevy rocker arms. | 
A heads-and-cam swap seemed like the best route to more Magnum power. Head flow on a production iron Magnum tops out at just a hair over 200cfm. |
More Magnum Vs. La-Series Information
The introduction of Mopar's Magnum series of engines was the most significant revision of the Mopar small-block since its introduction in 1964. There are some points to consider when deciding whether a Magnum engine is the right choice in an engine buildup and when mixing and matching components or applications.
Heads And Valvetrain
Magnums utilize 1.6:1-ratio pedestal rockers in place of the earlier LA-series engine's shaft-mount 1.5:1 arrangement. The LA engine provides oil to the rocker shafts via an oil passage in the block and heads. This was deleted in later Magnum engines, which rely on pushrod oiling via the lifters. Magnum heads can be retrofitted to an LA-series block, requiring lifters with oiling provisions (nearly all aftermarket lifters are so equipped) and the appropriate oiling pushrods. A Magnum block cannot accept LA-series heads without custom-machining the oil passages or creating a custom bypass oil-feed. For practical purposes this swap is a nonplayer, except in the case of very early Magnum blocks that were reportedly manufactured with the LA-style oiling provisions intact.
Magnums have a slightly revised head-bolt package requiring a Magnum-specific bolt set for use with Magnum heads. The head gaskets are also unique to the engine, although LA-series gaskets can be used in all applications. More choices in performance head gaskets are available for the LA-series design.
Intakes And Valve Covers
The Magnum intake has vertical fasteners, in contrast to the angled LA-series arrangement. This precludes swapping LA-series and Magnum intakes without modification, though it is possible to modify the intakes to work either way. Some aftermarket intakes are double-drilled to fit either engine. The fasteners and gaskets are also unique to the engine series.
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