Since the late '80s, World Products has been casting their own small-block heads. Known originally as the "Dart II," this successful design was employed by bracket racers and street heroes alike for a decade. Then, in 1994 World Products superseded the Dart II with the all-new Sportsman II head.
With its 200cc intake runners and fast burn-style combustion chambers, the Sportsman II head continues to offer engine builders the means to an easy, out-of-the-box 400hp small-block.
With more than 200,000 Dart II and Sportsman II heads sold, these World Products heads are as common in the pits as the Bow-Tie itself. But the company's president, Bill Mitchell, kept thinking "bigger" when he saw the Sportsman II-bigger intake runner volume and bigger valves-all to take advantage of the bigger displacement Mouse motors being built these days, including the 415-cid MoTown motors and 427-cid small-blocks his company was working on. We're talking engines that make north of 400 hp and exceed 500 lb-ft of torque-big-block territory, really.
But since World's expertise was in offering as-cast, off-the-shelf performance, he didn't want to bog down his technicians with hogging out Sportsman II heads. The solution was to cast a bigger, better small-block head. The MoTown 220 cast iron cylinder head is the result.
"You've got to match the heads' flow with the increase in displacement," Mitchell says. "It's the same old story about a big engine running out of breath at high rpm. If, say, you go up 10 percent in displacement, you should go up at least that far in cylinder head volume."
The MoTown 220, as its name implies, comes out of the box with 220cc intake runners. The 220 heads are available with either 64cc or 72cc combustion chambers (shaped for "fast burn" efficiency) and will accept intake valves sized up to 2.10 inches, although the standard assembled MoTown heads are fitted with 2.055 and 1.600 valves. Either way, the specs add up to seriously heavy-breathing chunks of cast iron.
"These heads really weren't designed for the average 350 small-block," Mitchell says. "They're for 383s and 427s that need to breathe at high rpm. You can achieve good benefits by putting them on a smaller-cube small-block, but the whole engine should be designed for it."
Mitchell points out that as-cast, the MoTown heads are beefier than stock-type heads with more material. This means someone with a die grinder and some time on a bench can extract more flow from the heads, but the already enlarged passages-compared to the Sportsman II heads-provide most of the benefits of a porting job right out of the box. World claims its "RightCast" casting method ensures cleaner, smoother ports, too, to lessen the need for "clean up" on the bench.
But just because the ports are big, does that mean they flow? We asked for some flow bench numbers, and Mitchell told us that the intake ports, for example, are 94 percent efficient at 28 inches of water flowing 290 cfm. The exhausts are good for 220 cfm.