W-2 Offset-Rocker Heads Configuration - Pump-Gas Punisher 360

Ever wonder what kind of power can be coaxed from a garden-variety street 360 short-block? You know, a basic bottom end, nicely built, with popular flat-top pistons at zero deck. We have always considered the production-style cylinder heads to be a limitation here. Sure 400 to 450 hp can be achieved easily these days, but even back in the day, Chrysler knew that getting the pushrods out of the way and really opening up the ports was the prescription for serious power. Want evidence? The precedent goes all the way back to 1970 and the Trans Am program. Mopar engineers knew that to reach the power levels required in their racing engines, something had to be done about the port constriction between the parallel pushrods. To homologate a package for the racing effort, production T/A engines had special cylinder heads with offset intake rocker arms, and intake pushrods tilted at an angle away from the port runners. The relocated valvetrain was the only change made to the street Trans Am castings. The casting and ports remained the same. Although the pushrod bulge still protruded into the port, as with any "X" head of the time, the bulge wasn't providing for pushrod clearance in the offset-valvetrain T/A heads. In fact, with the pushrod drilling angled to meet the offset rockers, the bulge was just a solid chunk of iron that could be cut away completely in the porting process.

All serious small-block heads were built upon the concept of the T/A heads because they worked. The most famous of these special offset-rocker heads has to be the W-2. Officially introduced in 1976 as part of Chrysler's Direct Connection parts program, the W-2 has earned a reputation of making the already strong running small-block invincible. The pinnacle of the W-2's fame was reached in 1979, when Bob Glidden destroyed the Pro Stock field with his W-2 small-block Plymouth Arrow to win the Pro Stock championship. The W-2 has seen continuous production ever since, and has been offered in many versions with the same basic port configuration. While the W-2 was a dramatic success as a race head, its performance characteristics were such that it also made a phenomenal street piece. The ports could support tremendous airflow; the port size was not excessive, and W-2 engines exhibited broad power curves. A well setup W-2 engine will make great torque lower in the rpm band, but just keep pulling as the revs fly, making seemingly endless power upstairs. W-2 small-blocks have long been feared on the streets.

Taking The Plunge
Switching to W-2 heads takes a little more than simply bolting on a pair of heads. offset W-2 rockers are needed, and with any of the long-valve heads, corresponding pushrods are needed to match the increased distance to the rockers. Since the intake port is much wider than a production casting, the intake manifold bolt pattern is spread. This, along with the W-2's unique oval port shape, requires a dedicated W-2 intake manifold. On the exit side of the head, the ports are substantially relocated requiring a wider bolt pattern to give acceptable header tube clearance; so dedicated W-2 headers are required, as well. all things considered, the changes required aren't prohibitively complex, just headers, intake rockers, and maybe pushrods. The question remains-what kind of power can be expected?