The Amsoil/Mopar Muscle Engine Challenge - Chenoweth Speed And Machine

When it came to choosing a camshaft for this engine, Mike and Dale Chenoweth decided to be somewhat conservative. Knowing this engine would run on pump gas and likely end up in a street car, they decided to sacrifice peak numbers slightly to broaden the power and torque curves of their engine. Though not small by any means, the Comp .660-inch lift solid roller cam had 252/263 degrees of intake and exhaust duration respectively. Installed at a 108 centerline and spun by a Pro-Gear double roller timing set, this cam did make peak power right at the contest limit of 7,000 rpm. To finish off their short-block, the Chenoweths used a stock timing cover and ATI balancer. To keep everything lubricated, a Melling standard volume oil pump was combined with a Milodon PN 30931 oil pan, a custom made crank scraper, and a Milodon single-line external pickup and oil pump cover.

Since this year's Engine Challenge featured spec engines, all the competitors were required to use the same Indy SR cylinder head. Starting with a level playing field, each engine builder had to look for incremental gains through porting and valve work to gain an advantage. Chenoweth Speed and Machine utilized Indy's CNC ported version of the SR head and did additional port work in-house to optimize flow. Manly stainless steel valves, PN 11380 intake and PN 11381 exhaust, were utilized and the valves and seats were treated to a custom valve job. Comp PN 947-16 valvesprings were utilized, and Harland Sharp rocker arms with a 1.7 intake and 1.6 exhaust ratio actuated the valves. Since their Comp cam was .660 inch valve lift based on a 1.5 rocker ratio, the 1.6 and 1.7 ratio rockers actually made valve lift .748 inch on the intake side and .704 on the exhaust side. Smith Brothers custom pushrods combined with Comp solid roller lifters were used for their durability. For induction, the Chenoweths chose an Edelbrock PN 2893 Super-Victor intake, topped with a Quick Fuel prepped 1050 Dominator carburetor. During their dyno pulls, however, they changed to an 1150 Dominator carb and gained a few horsepower. To ignite the mixture, an MSD PH 8546 Pro-Billet distributor was utilized along with a modified intermediate shaft with a Torrington-style bearing. Hooker PN 5209-1HKR headers handled expelling the spent gasses.