Regarding Crower's upgrade suggestions for its camshaft, Jim pretty much has it covered. He says the Tri-Power setup modified with the addition of the larger '66 center carb will flow 1,050 cfm. A set of Hooker Super Comp headers will be used on the dyno, and Jim is porting the stock heads to increase intake-port flow by 30 cfm. He thinks the stock exhaust flow of 180 cfm will suffice for this build. The compression ratio will be 10.6:1. While all this sounds great, remember the engine will have to retain the small 1.92-inch intake valve because chamber space is too tight for larger ones.

Along with proper parts selection, accurate machining and assembly are also important. Metallurgy of the critical parts is an area often overlooked, but not by Jim Taylor. Over the years he has amassed a library of data from investing in metallurgical testing with a well-respected laboratory. He wanted to confirm his parts are up to the task of holding the cylinder pressure that creates horsepower. Simply put, what good is the power if the engine does not last?

The engine build will be discussed in two parts. This installment includes the assembly and parts selection up to the long-block. Next time we will cover the induction system and the dyno testing to see if Jim meets his goal.

Since the story of this 421 is better told in pictures, follow along as we take you on this exciting journey!

HPP Engine Buildup Worksheet

Engine Displacement: 432 ci
Horsepower: See Part 2
Torque: See Part 2
Bore/Stroke: 4.150/4.00-in
Block/Crank combo: '64 four-bolt 421 / '64 OE 4.00-in stroke
Bore/Stroke ratio: 1.04:1
Rod/Stroke ratio: 1.65:1
Block description: '64 421ci #157
Preparation: Cook, bead blast, magnaflux, bore, true decks, align bore
Deck Height: 10.215-in
Crank: Original '64 421
Preparation: Magnaflux, check for equal stroke and index, grind, polish 0.010-in
Balancer: Original PMD rebuilt by Damper Doctor
Rods: Howard's billet 4340 certified steel, stock 6.625-in, floating pins
Preparation: Weigh, soap-and-water wash
Bearings: Sealed-Power mains and rods, cam Dura-Bond
Preparation: Install in rod, torque, measure ID
Pistons: Icon PN IC892 application 428 +0.030-in with 10cc dish
Preparation: Wash after balance for assembly
Piston-to-deck height: 0.009-in
Piston pins: Icon, SAE 1016 to 1022
Method used to retain pins in pistons: . Spiral clip
Rings: LPC (Liberty Performance Components) premium moly, standard tension
Preparation: File-fit for end gap if needed, wash
Rod bolts or studs/head bolts or studs: ARP cap screw supplied in Howard's rods / PMD
Windage tray: Original PMD '70 455, fabricate fit, no bosses at cap #2
Oil pan: 8-quart with extended pick-up, fabricated retention clamp
Oil pump: . . Melling PN M54D with 60 psi spring, made 70 psi at 6,000 rpm with 30W oil
Preparation: Disassemble, check ball seat for width, spring tension, plate clearance
Casting number: 97770716, '64 date
Chamber: Closed, special to PMD, 70 cc
Head mods: Port, cook, magnaflux, glass bead, convert to screw-in studs
Maximum flow at 28 inches of water
Intake: 218 cfm at 0.500-in
Exhaust: 180 cfm at 0.500-in
Compression Ratio: 10.6:1 effective
Valves: Competition Products stainless steel, 1.92 /1.66-in
Angles used in valve job: 30-deg intake, 45-deg exhaust seat, width 0.040-in intake, 0.060-in exhaust
Mods: Intake port match, valve bowl blend, improved short-turn radius
Retainers: Crower steel
Keepers: Comp Cams race locks
Valve guides: K-Line, liners
Valve seals: U.S. Seal
Rocker studs: ARP special 3⁄4-in bottom
Rocker arms: Crower roller, 1.6:1
Pushrods: LPC chrome moly
Diameter: 5⁄16-in
Length: 8.750-in
Brand: Crower PN 60311, solid
Duration at .050: 247/252-deg
Lift: 0.515/0.525 with 1.6:1 rockers
Centerline: 110-deg
Lobe separation angle: 112-deg
Installed position: 110-deg
Lifters: Crower solid with EDM oil hole (0.024 inch)
Valvesprings: Crower, dual no damper
Seat pressure: 110 pounds at 1.600-in
Open pressure: 282 pounds at 1.100-in
Timing chain: LPC, double roller
Carb: (3) Rochester two-barrels PMD
Size cfm: Total flow, 1,050 cfm
Mods: Built to factory specifications/ adapt '64 choke to '66 center carburetor
Jets, Primary: Center #64 adjust power valvespring for 12 Hg at 1,000 rpm
Secondary: Front and rear #70
Fuel pump: Will use 110-gph Carter
Fuel line size: 3⁄8-inch, 5⁄16-inch to carburetor
Intake manifold: Original '64 PMD tri-power
Mods: Flow-test indicated '66 center carburetor would be required to improve total cfm, adapter made to fit '66 center carburetor
Distributor: '61 Delco cast-iron with direct oiling
Coil: GM
Wires: NAPA Belden 7 mm
Total Timing: 36-deg BTDC
Initial advance: 18-deg
Mechanical advance: 36-deg at 3,200 rpm
Vacuum advance: Not used
Headers: Hooker Super Comp (for dyno test)
Primary tube diameter: 1.75-in
Primary tube length: approximately 31.00 inches
Collector size: 3.00-in
Brand: Fel-Pro head and intake/ SCE pan and timing cover
Along with proper parts selection, accurate machining and assembly are also important
Math, not gasoline, makes horsepower under the hood of a Pontiac

Jim Taylor Engine Service
P.O. Box 462
PA  18953
UEM Pistons