How to Build Performance on My 1970 351 Windsor
Machines, like men it is sometimes said, have their glory days and hours of waning. If you were ever to catch a late-model Windsor engine sitting at the bar and reminiscing, then it would almost certainly tell you stories about the days it spent dominating racetracks and drag strips through the late 1960s and early 1970s. The 1970 model year represents one of the best for this storied powerplant, so those looking for extra horsepower already have quite a bit going for them in terms of potential.
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Things You'll Need
- Engine building tools
- Stock 1970 Windsor heads, ported Windsor heads or aftermarket heads
- Windsor crankshaft, steel rods and pistons of choice
- Suggested camshaft kit and carburetor
Instructions
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Decide on a set of heads. Heads ultimately dictate airflow into and out of the cylinders, so consider this your foundation. The heads used on 1969 through 1970 351 Windsors -- casting numbers C90E B and D, D0OE C and G, and D0OZ -- aren't bad heads in their own rights. With 1.84-inch intake and 1.54-inch exhaust valves, these heads will support between 400 and 450 horsepower in almost stock form and over 500 when ported. The heads' 58-cc combustion chambers are small enough to build all the compression you'd want, so keep them unless you're looking to build more than 530 horsepower or so.
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Install a rotating assembly that will suit your needs. The stock 1970 351W crankshaft is nigh-unbreakable below 800 horsepower, particularly when you have the crankshaft rods and pistons balanced. If you're looking for more cubic inches, the 351W crank will take an offset grind to a 3.70-inch stroke; combine that with an 0.60-inch overbore and you've got 383 cubic inches. The stock rods are good to an easy 6,000 rpm, but replacing them with steel units is always a good idea. The stock pistons need only be replaced if you're looking for higher compression, have over-bored the block, want to use stronger forged pistons or lighter pistons for higher rpm potential.
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Choose a camshaft, lifter and spring combo to work with your heads. The stock 351W head flow maxes out at a 0.600-inch lift, but you may need to machine the valve guides to prevent bottoming out with that kind of lift. You're only giving up about 10 horsepower's worth of airflow at 0.500-inch lift, so keeping the camshaft in that range is a safer bet. For most applications, a retrofit Ford Racing F303 hydraulic roller camshaft -- 288 degrees advertised duration, 226 duration at 0.050-inch lift and 0.512-inch lift at the valve -- will make about 450 to 500 horsepower without pushing the engine past its limits.
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Top off your engine with a dual-plane aftermarket intake, a set of full-roller lifters, a set of under-drive pulleys, a non-points-type distributor, multiple-spark discharge ignition box, high-voltage coil, thicker plug wires, Iridium-tipped plugs -- gapped slightly wider than stock to capitalize on the stronger spark -- and a carburetor and headers sized to your horsepower and torque goals. Using the F303 cam, you should look for a set of headers with primaries measuring 36 inches long and 1.52 inches in inside diameter; a 2.64-inch collector will work best. A 600- to 650-cfm carburetor should provide adequate airflow to support 450 to 500 horsepower while maintaining a reasonable amount of manifold vacuum.
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References
- Ultimate American V-8 Engine Data Book, Second Edition; Peter Sessler
- Ford Racing: Camshaft Specifications
- Stan Weiss Racing: Cylinder Head Flow Data Chart
