THE SHOP

Performance & Hotrod Business - January '15

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January 2015 n PRECISION ENGINE n 5 Our Edelbrock Performer heads, P/N 60929, feature 84cc cham- bers, 2.140-inch intake valves and 1.810-inch exhaust valves, all swirl-polished stainless steel. Deck thickness is 5/8 inches. The Edelbrock heads feature 70cc exhaust ports and valve springs that accommodate up to 0.600 inches of lift. Valves have undercut stems to improve flow. The Edelbrock heads are designed with 210cc intake ports and angled spark plug ports. The Mopar Performance aluminum cylinder heads, P/N P5153525, also feature 84cc combustion chambers, 210cc intake and 70cc exhaust ports, with springs that accommo- date up to 0.600-inch valve lift. The exhaust flange has been extended 0.125 inches to provide dry exhaust manifold bolt holes. Spark plug ports are straight, (non-angled). Both the Mopar and Edelbrock heads were checked to verify combustion chamber volumes, (both burette checked to within 0.01cc of the adver- tised 84cc chamber volumes), test-fitted and checked for both piston-to-chamber quench and piston-to-valve clearance. Piston-to-quench (factoring in the MLS head gaskets) checked at 0.075 inches and valve clearance was 0.250 inches intake and 0.270 inches exhaust. Since we only had time to dyno one set of heads, we opted for the Edelbrocks. Cylinder heads were secured with ARP polished stainless steel 12-point head bolts, chosen for both tensile strength and outstanding no-maintenance appearance. Rather than using a conventional tin intake gasket that also serves to cover the lifter valley, I opted for individual composite intake mani- fold gaskets and an aluminum valley cover from 440 Source, along with billet aluminum rail hold-downs. This provides a much cleaner appearance as opposed to the stock setup. joining line with RTV, then removed the masking tape. This was done in order to achieve a neat and tidy appearance. (Note: I initially considered using Permatex "The Right Stuff " RTV to seal the valley cover, but I reconsidered, opt- ing for Ultra Gray. The Right Stuff is absolutely superb at sealing, but it's tough when cured and can be difficult to disas- semble something down the road, espe- cially a thin sheet metal piece like this val- ley cover, which would likely be deformed during an attempt to break the RTV loose. A high-grade RTV such as Ultra Gray (or Ultra Black or Ultra Blue) seemed a more sensible choice for this application. It does the job and is easier to break loose during future disassembly.) Cylinder Heads Two popular choices in performance cylinder heads include Edelbrock's P/N 60929 and Mopar Performance P/N P5153524. Edelbrock: The Edelbrock cylinder heads arrived fully assembled. They feature 84cc com- bustion chambers, designed for 1961-'79 Chrysler 361-440 engines. Specs include 15-degree valve angle, 210cc intake port volume, 70cc exhaust port volume, 2.140- inch intake and 1.81-inch exhaust valves, all swirl-polished stainless steel, with stem undercuts for better flow. Valve stem diameter is 11/32 inches. Valve guides are manganese bronze. Deck thickness is 5/8 inches. Valve springs feature 1.55-inch- diameter with a max lift capability of 0.600 inches. Spark plug locations are angled; designed for use with 3/8-inch pushrods. Mopar: The Mopar Performance cylinder heads, P/N P5153524 are also fully assembled. These cast aluminum heads will fit 1961-'78 Chrysler B (361, 383 and 400) and RB (413, 426 Wedge and 440) engines. These heads feature an 84cc com- bustion chamber, 210cc intake ports and 70cc exhaust ports. Additional features include phosphor-bronze valve guides,

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