Dyno Test: '69 351 Windsor
Owner: Rob Sharp
351W-4V, FMX automatic
Rob Sharp roared up in his Black Jade '69 Mach 1, which seemed to be the healthiest of our Mustangs. Rob had the advantage with a healthy 351W-4V engine with an aggressive hydraulic roller camshaft and 600-cfm Holley 1850 carburetor on top of an Edelbrock dual-plane manifold. However, Enyeart was about to do something no one expected: replace the Holley with an Autolite 4300.
Pull 1: BaselinePeak horsepower: 164.5 at 3,700 rpm
Peak torque: 256.06 lb-ft at 2,950 rpm
Air/fuel ratio: 11.0:1 at 70-mph cruise, too rich; at wide-open throttle, 10.0:1
Rob's 351W came right out of the chute with an attitude. It ran strong and never sputtered. The 600-cfm Holley 1850 delivered exceptional performance considering it was not fine-tuned beforehand.
Pull 2
Peak horsepower: 169.4 at 3,550 rpm
Peak torque: 262.49 lb-ft at 3,050 rpm
Air/fuel ratio: 12.8:1 at 70-mph cruise, leaner; at wide-open throttle, 12.0:1: still too rich.
With the factory 4300 carburetor, torque comes on strong at a low rpm. Horsepower is up as well. The 4300 yields a broader torque curve if you know how to tune it.
Pull 3
Peak horsepower: 172.5 at 4,100 rpm
Peak torque: 263.03 lb-ft at 3,150 rpm
Air/fuel ratio: 13.8:1 at 70-mph cruise; at wide-open throttle, 12.0:1
Enyeart tried a primary jet swap to 46s, .002-inch smaller to lean the mixture, which enabled the 351W to produce more horsepower and deliver a broader torque curve.