Small-Bore Pontiac Engine Build - Revenge Of The 350

The Crower hydraulic roller cam provides 0.549/0.573 lift, 290/296 advertised duration, and 234/242 duration at 0.050. Ken applies Torco MPZ (moly phosphorous zinc) assembly lube prior to installing it at 108 degrees. Despite the radical specs, the assembled engine idles smoothly on the dyno.

The billet timing set is by SA Gear (PN 78512W-9) and features a free-floating bronze cam plate bushing that wears better than one-piece factory-issue top gears. The double row chain incorporates seamless rollers for maximum reliability.

In keeping with the budget theme, the 383 uses reworked factory iron heads from SD Performance that retail for $1,495, fully assembled with your choice of springs. Based on #16 small-valve castings with 77 cc chambers, SD exchanges the 1.96/1.66 valves for better breathing stainless steel Ferrea 2.08/1.71 replacements. The chamber volumes are unaltered, save for a very minor deck cut to restore flatness.

The SD Performance heads feature filled exhaust heat crossover passages. These plugs are made of molten aluminum, salvaged from cast-aluminum pistons, that is poured in place, then cooled and machined.

The pen points to the filled region behind the center exhaust valves where the heat crossover passages used to be. SD uses a CNC mill to contour the area. No claim is made of improved flow, but since the center exhaust ports no longer communicate, the full benefit of four-tube header scavenging can be realized. Naturally, the need for blocked intake manifold gaskets is eliminated.

SD treats the 350 intake and exhaust ports to an efficient 5-axis CNC cut that enlarges them to standard 400/455 gasket sizes. On the SD flow bench, the massaged heads flow 255.7-cfm on the intake ports and 212.7 on the exhaust ports. Ken had SD equip them with Crower 130-lb (closed)/330-lb (at 0.573 lift) double valve springs (PN 68405) and chrome-moly retainers.

Thanks to its small bore and limited demand, there is only one Pontiac 326/350 head gasket set on the market today. It's made by Victor Reinz (PN 3401VC) and has a compressed thickness of 0.039-inch. The good news is it's a decent piece and stands up well to virtually any street and strip use.

With the ARP 1/2-inch head bolts (PN 190-3607) torqued down to 100 lb-ft, the Crower roller lifters are dipped in oil and installed. Failure to soak the rollers and pins can result in a dry start-up and galled parts.

Replacing the stock stud mounted rocker arms is a new Tomahawk TSR shaft-mount system. Retailing at $795, they fit all iron and aluminum D-port heads. The rugged 1.6 ratio billet aluminum roller rockers decrease operating friction and eliminate push rod push-through problems common to stamped steel Pontiac rockers.