I'm running the following set up in my Cobra:
408” 351W based stroker motor
Late model 351W factory roller cam block.
Crank: Eagle 4.0” Stroke Rods: Eagle 6.200” Pistons: Probe Industries Forged Aluminum SRS 4.030” bore, Reverse Dome 22cc (Compression ratio should be about 10.09:1 with these pistons and the Edelbrock heads with 60cc chamber volumes)
Cylinder Heads: Edelbrock Performer RPM 2.02” Intake Valves, 60cc chambers
Intake manifold: Edelbrock RPM Air Gap 351W
Carb: Holley Model 4160, 750 CFM, manual choke, vacuum secondary’s #0-3310C
Fuel pump: Summit Mechanical 110 GPH
Camshaft: Mike Forte Custom Grind 510/534 Lift, 222/232 duration at .050, 114 LC Camshaft Hydraulic Roller Lifters: Ford M-6500 R302
Roller Rocker Arms: Competition Cams #1131-8
Hydraulic Roller Lifter Retainer and Spiders: Ford factory
Crankshaft Damper: Ford Racing Nodular Iron, external balance #M-6311-K351
Oil Pan: Milodon 8 quart
Timing Chain Set: Edelbrock #7811 Performer-Link True Roller chain set
Distributor: MSD Pro Billet Small Diameter, Magnetic Trigger #8478, with vacuum advance
Distributor shaft Steel Gear (#85834) and installation by MSD factory
Superformance stock Ford Dura Spark ignition module coil
Spark Plug Wires: Ford Racing black 9MM
Spark Plugs: Champion RC12YC (Recommended by Edelbrock for use with their alum heads). Spark plug gap: 036”
Ignition timing is about 15 degrees initial, 21 mechanical for a total of 36 degrees all in at about 3,100 RPM
The Holley Installation, Tuning and Adjustment Manual for my carb says to use the timed spark vacuum fiting in the chock side of the primary metering block as opposed to full manifold vacuum at the base of the carb. Yet many people swear by using full manifold vacuum. Why? Which is a better source for the distributor vacuum?