After reading some of contributing editor Steve Dulcich’s articles on small-block Mopars and W-2 heads a while back, Robinson decided to give the iron W-2 heads a shot. “We wanted to explore what those had to offer on a stock stroke 360. So we picked up a set in probably around 2000.” They’ve been sitting on them since then waiting for the right project to come along. “They’re very expensive to get going because of the support equipment you need to run them. They take dedicated rockers, a dedicated intake, dedicated headers, and so on.” Those dedicated accoutrements are the result of the engineers at Mopar pushing the envelope. They were designed from a mostly clean sheet of paper with the caveats being that it must bolt to a factory small-block without major modifications and it should be cast iron to meet various class rules. The result was rather interesting.
Obviously the designers looked at the primary restriction of the small-block LA heads—the pushrod pinch—and made that target number one. Anybody who’s worked with small-block Mopar stuff knows how skinny the port entrance is and if you get greedy porting for power it is all too easy to grind through into the pushrod hole. Not good. The solution in the W-2 was to basically make that pushrod hole solid and run the pushrod cocked over at an angle meeting up with extremely offset intake rocker arms. With the possibility now of having a big-ol’ intake port, they also spread the intake boltholes out to match. On the back side, they followed suit by spreading the exhaust port pattern out to maximize pressure relief.
As was intended, Robinson ported pretty much all the way through the cast iron where the “old” pushrod pinch would normally be. The W-2 pushrod holes are machined into the head and thanks to the smooth finish on the pushrod holes, Robinson was able to press in a sacrificial aluminum tube. Once he ground to the end of the cast iron and struck aluminum, he’d have something to seal the runner from the inside of the engine. The only downside of that was that he was forced to use a spindly (but thick) 5/16-inch-thick pushrod on the intake side instead of a beefy 3/8-inch pushrod like he had on the exhaust.
Robinson followed the path of his flow bench to get the flow numbers where he wanted them and then fine-tuned them on the dyno. He added about an 1/8 inch of epoxy to the floor to try to shrink up the port and raise the average runner height but said in the end it didn’t pick up over his already hot port work. Another spot he worked the epoxy magic was in the area around the valveguide. Cylinder head experts have been playing with wing designs behind the guide for decades and it seems there is no real consensus as to what works best. Robinson built up a basic straight-on wing to help guide the fuel and air to the spot in the chamber he wanted it entering.
The W-2s require extra-long valves and Robinson went through a couple different valvespring setups in order to control them without wasting energy in friction. Initially running dual springs with close to 230 pounds on the seat, he backed off and switched over to lightweight beehive springs. T&D Machine 1.65 ratio rocker arms were chosen for their consistently high quality. “I can’t say enough about the T&D rockers. They’re pretty much flawless.”
One of the other W-2 deals is that they oil through the pushrods instead of through the block. While building their 360, the team paid attention to the oil system to make sure there was adequate fluid up top. Running a crossover oil line from the rear of the passenger side to the front of the driver side equalized flow to the hydraulic lifters. With oil flowing through the lifters and the hollow pushrods, the oil holes in the deck of the block were rendered obsolete. Some engine builders choose to block the holes while others just let the cylinder head or the head gaskets block them.