My Superformance 351W based engine starts fine and under mild acceleration runs strong and great. When I floor the car it kicks, spits and stumbles really badly though.
I've been through the brand new Holley carb and made sure that the secondary float is adjusted correctly and verified that the secondaries are flowing fuel just fine. I have also replaced the Holley secondary vacuum spring to a lighter spring but this has not made any difference with the basic problem. I've installed the MSD distributor with the the Superformance factory stock Duraspark II ignition module. I've carefully double checked all of both the primary and secondary ignition wiring against the factory wiring diagram and even replaced the Ford factory coil to no avail.
I used the (MSD) two 2 blue (light) springs and the blue bushing which should be giving me about 21 degrees mechanical advance coupled with my 15 degrees initial advance or 36 degrees total, all in by about 3,100 RPM.
Here are more specs on the very recent engine build.
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 Duraspark 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: .045”
Again, when accelerating at partial throttle the engine runs just fine and has plenty of power but as soon as I really kick it the engine falls flat on its face kicking, spitting and refuses to run right until I get back off the throttle partially, where it continues to run just fine.
Please let me know your thoughts on where the problem is here. Thank you.
Need help with driveability problem...
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