The Shermanator 347

A 530hp Gas Stroker You Can Build.

Joe Sherman Racing in Santa Ana, California, is one of those "boutique" engine shops that cater to local racers and street guys who have a real need for speed. It doesn't matter if you bring him a Chevrolet, AMC, Oldsmobile or Ford, Sherman relies on his trusty flow bench, dyno and his 40-plus years of experience to put together a winning combination. Unlike many engine builders, Sherman has a thorough understanding of the complete racecar package. He and his sons have raced incredibly quick bracket cars for years. Sherman knows from first-hand experience how much power you need, and where in the powerband you need it. Wringing every last ounce of useable power out of a given combination is his specialty; in fact, he won the 2002 Engine Masters Challenge-kickin' butt on engine builders from across the country.

STROKED WINDSORS
The plan was to build a 347 to run on pump gas, make 500 hp, and not break the bank.

Initially the 347 was to be built around a budget rotating assembly. Sherman ordered the parts and when the pistons arrived with several different styles of valve notches, he reverted to plan b, using engine components he knew and trusted. It would cost a little more, but knowing the engine would stand up to several seasons of 7,000rpm abuse would more than make up for the difference in price. Sherman is definitely on the frugal side, but he spends money where it counts-on anything that enhances reliability and power output.

The block is a late-model production 302. The reason we mention this is later blocks have slightly different deck heights than early blocks. This block ended up with an 8.18-inch deck height after final machining. After inspecting the O.E. main bearing caps he made the observation that they look a little "delicate," so he installed a CAT main bearing girdle that requires no machining. It helps retain the Scat 9000-series cast crank that features radiused counterweights and chamfered oil holes. Sherman has used a number of Scat cranks in the past and swears by their quality, durability and price. The crank rotates in Speed Pro Competition Series bearings with clearances kept on the tight side of recommended tolerance.

Scat got the call for the connecting rods as well. Sherman selected a set of 4340-forged I-Beam-style rods that measure 5.40 inches center-to-center. The longer rods (stock measure 5.09 inches) allow the pistons to clear the stroker crankshaft counterweights and provide a more favorable rod-to-stroke ratio. These rods come with ARP bolts and are bronze-bushed for full-floating pins and drilled on the pin end for oiling because it takes power to stop and accelerate a piston twice per crankshaft revolution. The JE forgings (PN 188703) fit his requirements perfectly. They feature a flattop design and weigh a mere 414 grams plus another 105 grams for the Chevy-size premium piston pin. A set of 1/16-, 1/16- and 3/16-inch file-fit Speed Pro rings provide the seal and glide on cylinder walls that are finished with an 820-grit stone. The oil ring is a low-tension design but has enough oil control for a street engine without the assist of a vacuum pump. The remainder of the bottom end consists of a stock pressure and volume Mellings M-68 oil pump and a Stef's welded aluminum, high-capacity oil pan.

CAM DOCTOR
Sherman is constantly doing R&D on camshaft profiles to find more horsepower, however, he's really pleased with COMP Cams' latest series of solid roller profiles. The cam he selected for this pump gas 347 measures 248/252 duration at 0.050-inch, and 0.662 and 0.648 inches of lift at the valve with 1.6 ratio Jesel's SS shaft rockers. It's ground with a 108-degree intake centerline and installed in the motor "straight up." Due to the aggressive profile on this cam, Joe feels that the effective duration is more than the specs would indicate. In fact, the dyno tests revealed that this engine combination could use a little less cam timing because the actual compression is only 10.5: 1. When the valve lash was increased (decreasing duration) it picked up the power.

Jesel shaft rockers may sound extravagant for a pump gas street engine, but not when you take a closer look. Jesel's Sportsman Series (SS) shaft rockers retail for under $700, which is no more than you would pay for a set of good aftermarket studs, roller rockers, guideplates and a stud girdle. Plus you get all of the advantages of shaft rockers such as better geometry from the rocker's longer pivot length, the stability of the shaft that ties it all together and hi-strength adjusters that maintain valve lash longer.

The real key to making 530 hp from 347 cubic inches on pump gas is the Airflow Research (AFR) aluminum cylinder heads. AFR is selling these heads like hotcakes. They come in a few different sizes and options. Sherman selected AFR 185s for this engine. They feature Chevy-size 2.02/1.60-inch stainless steel valves and 58cc combustion chambers that set the compression ratio at 10.6:1 with the 0.053-inch Cometic head gasket (more on that later). Sherman ordered the optional AFR 8000 roller cam spring package that includes springs set at 210 pounds on the seat and 550 pounds open. They will accommodate valve lifts up to 0.670 inches and come with titanium retainers. Sherman slapped them on his flow bench and performed some minor porting. He's amazed at how good these heads are out of the box. He said that the heads are held in place by ARP hardware.

INTAKE THINGS
Things got interesting in the 347's intake system. He heard that there were some excellent components on the market that would make the power numbers he wanted and save a few bucks in the process. He selected a Professional Products Hurricane single-plane intake manifold that is available in a satin or polished finish. It has an rpm range of 3500-8000 rpm and has some neat features such as integral bosses that can be drilled and tapped for nitrous nozzles. It retails for about $50 less than similar manifolds sold by other manifold makers, but produced good power on the street 347. Before testing, Sherman went in and smoothed the port dividers in the plenum area. He said that he does this regardless of whose manifold he uses; the Hurricane just needed a little more grinding than usual to meet his approval.

The carburetor choice was a big surprise from little known, but quite capable, Quick Fuel Technology (QFT) in Bowling Green, Kentucky. Sherman gave them his engine specs and application and let them design a carburetor to match the application. No wimpy 750 here! QFT provided one of its Q-Series 950cfm 4150s. They started with a ProForm carb body, bore the venturis out to 1.450 inches, installed double-step downleg boosters and a billet aluminum baseplate with 1 3/4-inch throttle blades. The throttle shafts are milled and use button-head screws to improve flow. On the metering side, QFT two-circuit billet metering blocks are installed with four-stage emulsion. Other features include notched floats, jet extensions and high-flow squirter screws. QFT's Q-Series carbs are streetable with timed vacuum ports, PCV and full vacuum ports. However, they don't come with a choke. With its $639 retail price the Q-Series is a race carb on a regular carb's budget.

SOME ASSEMBLY REQUIRED
Sherman assembled the 347 with Fel Pro gaskets and ARP fasteners. Everything went together as planned, except the pistons ended up 0.010-inch above the deck. Joe hadn't realized that he was using an early block with the shorter deck height. No problem! His ace-in-the-hole was the Cometic Multi Layer Steel (MLS) gasket that is available in thicknesses from 0.027 to 0.120 inches. The 0.054-inch-thick gasket was just the ticket to establishing the correct clearances. Other details include a Ford distributor set up with a mag pickup trigger mechanism and an MSD ignition box. SVO valve covers add a bit of style.

Sherman hooked the 347 to his trusty Superflow 901 pump, installed 1-3/4-inch dyno headers and 3-inch Magnaflow mufflers. He threw in a set of Accel 784 sparkplugs gapped at 0.045 inches and set the timing for 38 degrees total. A set of #78 primary and #86 secondary jets were selected (after a few warm-up pulls) to meter the 91-octane Shell gasoline. Joe made more than 14 dyno pulls in all, optimizing ignition timing, valve lash and jetting. The final result was 527 horsepower at 7,000 rpm, and 443 lb-ft of torque at 5600 rpm. An amazing side note is that the torque never dropped below 400 lb-ft from 4800-6800 rpm. Joe experimented with a larger 1050 cfm QFT carb and larger cam and produced 530 horsepower at 7,000 rpm but slightly less torque, so he stuck with his original design instead. What Joe Sherman has put together here is a pump gas small-block that has an ideal power curve on a budget that most of us can relate to.