Stock-Stick Special
Anthony, via CarCraft.com: Hey guys, I just read Matt King's article on the 400hp 302. I was wondering if I can do the same thing with my '69 302 or something close to it. If so, any chance of letting me know what I need to get my 302 kickin'?
Terry McGean: You just read that? We did it three years ago ("400hp With a Stock Cam," July '03), but it was a good piece. Although the power numbers were impressive, there really wasn't much trickery to Matt's combo. The real key was a set of Airflow Research (AFR) aluminum heads. The 165cc intake-port heads for the small-block Ford might sound small when compared with the 195cc and 210cc ports commonly touted for aftermarket small-block Chevy heads, but AFR intentionally kept the ports smaller to promote intake velocity. These heads still flow like mad (about 245 cfm on the intake side) and allowed the 5.0 to really wake up. One of the interesting things revealed by this experiment was that the stock cam used on '87-'93 5.0 H.O. engines is actually rather hardy for a factory EFI grind (0.445/0.445-inch lift with stock 1.6:1 rockers; duration from Ford is 276/266 at 0.006-inch lift, which is reputedly around 210 at 0.050). In fact, realizing big gains in power by changing the heads and not the cam indicates that the stock heads are the "cork" in these 5.0s, not the cam, as is often the case with factory engines. This may explain why changing only the cam on a stock 5.0 doesn't bring power up all that much. Matt did use a set of Crane/Ford Racing 1.7:1 roller rockers to gain additional lift, bringing it to 0.473/0.473-inch, but the rockers alone would not make that much difference if the cam weren't already fairly healthy.
The only major differences between your '69 302 and Matt's later version are the roller cam, which began for '85 on H.O. engines, and the piston design, though the latter is not radically different. Since the stock '69 302 heads had combustion chambers of around 63 cc that produced about 9.0:1 compression, bolting a set of the AFR heads to your engine should yield similar compression (with the 60cc chambers and a thick 0.041-inch-thick head gasket, Matt's 5.0 had a little over 9.0:1). You could use a flat-tappet cam of similar grind to replicate our efforts. Comp Cams offers a grind in its High Energy line that is similar (260H) with 212/212 duration at 0.050-inch lift and 0.447/0.447-inch lift (with 1.6:1 rockers), though like most Comp grinds, this one is on a 110 lobe-separation angle, whereas the stock 5.0 cam is said to be around 114-115. Comp describes this as "an excellent combination of torque and power; best for towing with 302 and stick trans." In other words, you can do better if you're trying to make horsepower. For instance, the Comp Xtreme Energy line features a grind with 218/224 duration at 0.050 and 0.493/0.500-inch lift that is said to be compatible with a stock converter, so the idle is probably still reasonable if that's a concern. Another concern, however, is whether this cam will cause piston-to-valve conflicts. Matt figured his late-model pistons could handle up to 0.220 at 0.050 without a problem, and your valve reliefs may be deeper, but you'll have to verify that and remember that the big (relative to factory spec) 1.90/1.60-inch valves of the AFR heads will need more room than stockers.