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 Then, in 1994 World Products superseded the Dart II with the all-new Sportsman II head.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.
The research and development process for the MoTown heads consumed a year and a half of World's co-owner and chief "R&D" man, Gary St. Dennis', time.
"Moving, lengthening, or enlarging one set of ports can affect the others," Mitchell says. "It would have been easy to remove the heat riser, but because we wanted these heads to be street-friendly-and pass emissions testing-we had to be careful with the ports' design. Of course, they needed to flow well, too."
The MoTown 220 head carries a CARB exemption number, making it street legal in California-and everywhere else in the country. Since the new head fits the same engine family of the already CARB-blessed Sportsman II, getting the heads CARB-approved was a little easier. Basically, it meant running a car with the heads at an approved emissions lab. When the car passed, then so did the heads.
Because they are designed as drop-on replacements for production-style small-block heads, the MoTown 220 heads accept stock-type exhaust manifolds and require nothing unique to bolt them in place. The end pads will accept both early- and late-model accessories, while each head accepts either perimeter-style or center-bolt valve cover designs. (And because World Products is an OE supplier, its manufacturing process is QS-9000 compliant. This means the heads are built to OE-style standards.)
The World Products 415ci MoTown crate motor wears the 220 heads and is rated at 450 hp and more than 500 lb-ft of torque. The heads are a major reason for those impressive numbers.
"A big-inch engine needs to move a lot of air," Mitchell says. "These heads do it."
With figures like 450 hp and 500 lb-ft, he'll get no argument from us.
On the flow bench the Motown heads' intake port flows about 290 cfm at 28 inches of water, while the exhaust port flows 220 cfm. Not too shabby for an as-cast, un-ported head.
On assembled heads World employs Manley Race Master stainless valves. The standard size for the 220 head is 2.055-inch intake and 1.600-inch exhaust. World says a 2.080-inch intake valve will work, too, with a 1.625-inch exhaust valve for ported applications. Heck, if you leave the exhaust valve at 1.600, you could drop in a 2.100-inch intake valve. In comparison, the stock valve on World's Sportsman II heads is the already big 2.020-inch intake.
Like other heads, the 220 utilizes cast intake valve seats and hardened steel exhaust seats. Note here the bean-shaped combustion chamber, which gives the head its fast burn properties. The standard small-block chamber is more D-shaped. Also, the 220 has a maximum flat mill depth (up to the intake seats) of .040 inch.
The MoTown 220 head is named for its 220cc intake ports. For comparison, a stock-type small-block head has 170cc intake ports, while World's own Sportsman II head has 200cc ports. With the 220, it's almost like getting a ported head right out of the box.
The MoTown head is designed for hydraulic and solid roller cams. Manley springs are used in complete assemblies, with 1.437-inch dual-springs on hydraulic applications and 1.550-inch duals for solid rollers. The heads are designed for screw-in rocker arm studs, too.
World Products sells bare MoTown heads, but they offer complete assemblies, which seems like the hot setup to us. As an OE supplier, World's manufacturing process conforms to OE-style quality standards.