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Essential Information For Cams And ValvetrainsThe Camshaft And Valvetrain Are The Brains Of The Operation From the February, 2009 issue of Chevy High Performance By Jeff Smith Photography by Jeff Smith
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 Hydraulic-roller cams have...  Hydraulic-roller cams have become the new darling of the performance world. The least expensive route is to build an 87-or-later small-block that came with a hydraulic-roller cam so you can employ factory hydraulic-roller tappets. This is the GM Performance Parts Hot cam and accessories for a hydraulic-roller-cam block.  Flat-tappet cams (below) are...  Flat-tappet cams (below) are less expensive than hydraulic-roller cams (top), but a roller offers significant power potential, especially for mild street engines.  Rocker arms are an easy way...  Rocker arms are an easy way to add valve lift to an existing camshaft. Shown from the left are stock stamped rockers from Crane, Crane Gold Race aluminum rollers, and Comp Cams Pro Magnum roller rockers.  Rocker-arm ratio is based...  Rocker-arm ratio is based on the distance between the pushrod cup and the centerline of the rocker. To increase the rocker ratio, the pushrod cup moves closer to the rocker centerline. The rocker on the left is a 1.52:1 ratio, and the rocker on the right is a 1.6.  More aggressive camshafts,...  More aggressive camshafts, especially hydraulic-roller cams, require stronger valvesprings. One way to accommodate more lift is with a larger- diameter spring that increases the spring pressure. Stock small-block springs are generally 1.250-inch outside diameter (od). Larger 1.440-inch springs are the next step up.  Crane makes an excellent H-11...  Crane makes an excellent H-11 Tool Steel spring that will fit the confines of the stock small-block spring pad while offering a 406-lb/in rate that can handle up to 0.600-inch valve lift. This spring requires a guide with an inside diameter no larger than 0.760 inch.  ARP makes an excellent poly...  ARP makes an excellent poly lock called the Perma-Lock, which offers a 12-point hex that prevents the wrench from slipping down over the lock during lash adjustment. This is a very useful feature for adjusting valves.  Adjusting valves is easy if...  Adjusting valves is easy if you remember this simple procedure. When the exhaust valve just starts to open, adjust the intake. Then bump the engine over and when the intake is almost closed, adjust the exhaust. The shorthand is exhaust opening (EO), intake closing (IC)or EO-IC.  GM Performance Parts makes...  GM Performance Parts makes an interesting 1.330-inch-od spring for 96 LT4 engines. It employs an ovate wire to increase valve-lift potential (kit, PN 12495494; spring retainer, PN 10212808). This spring can handle up to 0.510-inch valve lift. If cylinder heads are the heart of an engine, then the camshaft and valvetrain have to be the brains of the operation. Timing the opening, closing, lift, and duration of each valve event is central to increasing power and torque. While something this complex might seem expensive, the price of camshaft admission is surprisingly affordable. Rather than deal specifically with camshafts in this particular story, well focus instead on several options that you can take concerning rocker ratios, poly locks for the street to maintain that valve lash, and how to save a little money on your next engine buildup using a hydraulic-roller camshaft. So climb on board as we take a high-tech ride on the valvetrain.
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Automotive Racing Products (ARP)
531 Spectrum Circle
Oxnard
CA
93030
805-278-7223
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GM Performance Products
Contact your nearest dealer
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COMP Cams
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Scoggin-Dickey Parts Center
Lubbock
TX
N/A
www.sdparts.com
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Crane Cams
530 Fentress Blvd.
Daytona Beach
FL
32114
3-86/-252-1151
N/A
www.cranecams.com
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FrankenRat, Part III
Tired of fooling around with a mild camshaft, our demented Dr. FrankenRat has bolted a serious...
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Camshaft Basics
The camshaft is unquestionably the most complex component in the internal combustion engine. The...
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