My brother, Dan, rebuilt two different W72 400 engines, a ’78 and a ’79. The ’78 W72 was the original engine in his ’78 WS6 TA which was modified in an earlier life, then removed for an SD-455 engine. The original 400 (completely torn apart with original rods missing) was already .030” over and needed .040” over pistons to clean up the cylinders properly (so new custom forged pistons and Eagle H-beam forged rods, but ignore this if your short block is good). With rebuilt stock 6x-4 heads minimally cut for trueness, new Ferrea 1-pc stainless valves, CC springs, etc., the static compression worked out to 8.75 to 1. He installed a Summit 2800 cam with old (never used) Crane hydraulic lifters, old factory RA exhaust manifolds, original factory cast iron intake manifold and original Q-jet rejetted for more power on the dyno. With the small 2800 cam, it made 360 hp/456 lbft torque (at 5000/3600 rpm respectively).
The ’79 W72 was a stock std. bore rebuild (new rings on original cast pistons) with minimally cut 6X-4 heads, new valves, etc., stock manifolds (intake & exhaust) & Q-jet. The static compression was 8.10 to 1. Dan had a custom cam (CC) made with 201/219/110 @ .050” with .420”/.450” lift to try to emulate the original ‘402’ cam specs as much as possible from their standard lobe selections. It made 329 hp/413 lbft torque (at 4900/3400 rpm respectively). This was through stock exhaust manifolds and 2.25" headpipes (not mandrels bent pipe).
Steve25 is right on with the ‘402’ cam being a pretty good grind and the Summit 2800 and the Crower 60240 cams are good replacements. The 60240 would probably like more compression in the 8.5-up range, however, we’ve never used one yet.
Dennis
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