The carb wanted 81/86 jetting, the 2-inch spacer was critical, and the headers wanted the Hooker 18-inch collector extensions rather than the cheaper 12-inch Flowtech ones. The timing was best at 36 degrees total, and the HEI's curve was so slow that all the timing wasn't in until 4,000 rpm. We learned that the Edelbrock Super Victor was way too big for this engine (it killed as much as 15 hp compared to the Victor Jr. with the spacer), and we saw identical power curves with either VP C14 fuel or Rockett Brand 93 octane. Windage did not seem critical, as power was unchanged whether we ran 5 or 4 quarts in the pan (we often find a little power running a quart low). We ran Royal Purple oil in a heavy 20W50 thanks to the engine's blow-by. Though every cylinder cranked a decent 170-180 psi, this thing smoked badly through the borrowed valve covers. Ring seal was nada.
In retrospect, 1.34 hp/ci is impressive for an engine with a bone-stock bottom end and what later proved to be 0.010-inch bore taper. Besides, we'd managed to make nearly 470 hp for a total investment of $2,341.18. We just hadn't hit that magic 500hp number, and we set out to find it. Even if it involved some thieving.
King's 350: 515 HPIt was three days before the magazine shipped to the press, and we needed a quick solution to bad ring seal. If we were going to put rings in it, we might as well throw in some slugs too. Aftermarket pistons could buy some needed valve-relief depth as well as pick up the compression. Dulcich is the master of hand-cut valve clearance, so we even considered a standard-bore set of Speed-Pro L2256 pistons that could handle lots of cutting (and would need it) and that we could install after a simple bottle-brush hone. It wasn't the most reasonable solution, especially with a huge ring ridge at the top of the cylinders of our 350. It seemed we'd need to bore the thing.
Then it struck us: Matt King built an engine with exactly our mindset when he was the Car Craft editor. It was based on a standard-bore ZZ4 that just took a hone and a deck cut to get nearly 11.0:1 compression using Probe pistons with decent-valve reliefs and, best of all, 3.5cc domes. King had left town with the engine in storage, and he left us the key. When we found his 350 on a rolling engine stand with a lift plate bolted to the carb pad, we figured that constituted both destiny and permission. It was exactly the type of stock short-block we'd have built, plus it had a Milodon pan, so we nabbed the sucker.
A day later, our top end was bolted to the fresh 350 with the Probe dome-tops squeezing almost exactly 13.0:1 with the 54cc chambers, 3.5cc domes, and new Fel-Pro gaskets with 0.039-inch compressed thickness. Ahhhh, perfect-except valve-to-piston clearance remained a problem. King's monster Lunati 259/265 at 0.050 cam wouldn't fit; neither would our earlier Lunati stick. We were determined to make this one a bolt-on with no hashing of the pistons, so a thrash test-fitting of five different cams finally found us with a Comp Cams 292S, a solid flat-tappet with 248/248 at 0.050, 0.525/0.525 lift, and a lobe sep of 110 degrees. That cam had just enough valve-to-piston clearance with the Probe slugs at 0.005-inch below the deck and the 0.039-inch-thick head gaskets. However, we lost a small battle when the piston domes barely contacted the cylinder heads, a problem easily solved with 10 minutes of grinding minor divots in each chamber.
With more compression, better ring seal, and a smaller cam, would we make our number? Yep: 515 hp at 6,800 rpm and 457 lb-ft at 5,200. With 13.0:1, it only runs on high-octane gas, but we were able to run without detonation on Rockett Brand 100 octane that you can buy at the pump in some parts of the country. Inconvenient perhaps, but compression is your pal when trying to make big power with budget cylinder heads and flat-tappet cams.