Additional 195 hp

Starting With a 250hp Replacement Engine, Joe Sherman Racing Adds an Additional 195 hp

Some time ago, Chevrolet began lowering engine compression (to 8.50:1) in an effort to meet tailpipe emissions numbers. It also retarded camshaft timing in an effort to lower NOX (nitrides of oxygen/unburned particulates).

By 1974, horsepower, torque and overall engine efficiency had dropped some 30 percent to 50 percent. Chevy’s RPO L48 and LM1 350 small-block V-8s then got a flow-restrictive catalytic converter in 1975, and finally in 1985, a new monolith catalytic converter, as well as direct-port fuel injection and improved camshaft timing, boosted horsepower, torque and engine efficiency.

These ’71-’84 low-performance 350 V-8s are quite similar to the GM “Targetmaster” crate engine. It has been available over the counter since the late ’70s in long-block form (no induction or ignition) as a direct replacement for Chevy cars and pickups. It is assembled from brand-new parts and is not a rebuilt/remanufactured engine.

Its cast-iron heads feature 1.94- and 1.50-inch valves with 72cc combustion chambers. Its pistons are cast-aluminum dished types, the connecting rods are H-beam types, the crankshaft is of nodular-iron configuration, and the iron block features four-bolt-main bearing caps. The compression ratio is 8.5:1 and the camshaft is a hydraulic, smooth-idle, low-lift, non-performance grind. With a cast-iron intake manifold and four-barrel carburetor, horsepower is estimated to be in the 250 range. We know that this is acceptable for many, because GM sells a lot of Targetmaster 350 engines. But this is not an engine for anyone reading TheAutoBuilder.

We have, however, always wanted to know what potential this engine might have if it were to use a streetable performance camshaft, matching high-rise intake manifold and correctly jetted carburetor. It was our guess that 300 hp to 325 hp and 300 to 330 lb-ft of torque would be easily attainable.

The new GM Targetmaster 350 uses cast-iron, 74cc combustion-chamber heads, casting number 462624. The valves’ face diameters are 1.94-inch intake and 1.50-inch exhaust.

This is how the factory assembled the lower end. It has four-bolt-main bearing caps on the No. 2, No. 3 and No. 4 caps, along with a nodular-iron crankshaft. It works well to 6,000 rpm. The smooth rod caps were interesting to look at. Also, no oil filter adapter is included from the factory.

The factory Targetmaster pistons are cast-aluminum dished type. Why the top and bottom eyebrows? These pistons were engineered to be installed either way. There is no piston dome, top or bottom, per se. Cast pistons have been known to crack on the skirts or at the wrist pin during cold operation and also high-rpm use. Because this modified engine would rev to 6,000 rpm, a switch to stronger Keith Black (KB) forged pistons was made. This is inexpensive insurance!

The Targetmaster oil pan is a standard 5-quart with no baffling or trap door. Note that the pan (and therefore the block, too) has been tooled for left and/or right dipsticks. Therefore, you can install yours where you prefer.

For the record, GM Performance Parts gives the Targetmaster cylinder walls a nice crosshatch pattern, so the rings seat quickly.

We liked the reinforcement pan rails. These flat, metal torque plates help distribute the torque of each pan bolt, which pretty much guarantees no future leaks from the oil pan gasket.

We Want More!

Fine, you say, but what’s the absolute peak output? What can a Targetmaster 350 produce with a little better compression ratio, a better camshaft, bigger heads, and premium induction, ignition and exhaust? And finally, what would the approximate cost be for this total package? Like you, we have seen numerous engines advertised around $4,500 to $4,999, so we thought the Targetmaster deserved a closer look.

With this in mind, we ventured to Santa Ana, California, to visit with respected engine builder Joe Sherman, who won the Small-Block Engine Masters event in 2002 with a 365ci small block featuring 11.4:1 compression. Its peak horsepower and torque outputs were 604 at 6,500 rpm and 528 at 5,100 rpm. Its average horsepower and torque across the entire rpm range were 422 and 482, respectively. Sherman earned a cool $75,000 for his efforts, so you know going in that he knows engines and how to build one by matching engine parts correctly.

An interesting side note: Sherman was also one of the very first to make a 409 W-motor produce enough power to make a Chevy Bel Air run 10.70 e.t.’s. That was some 15 years ago, and he put a bunch of quarter-mile passes on that car.

Sherman builds Chevy street and race engines for customers as far away as Sweden and Norway, and he is a master at getting the potential buyer to state exactly what he wants his engine to do. As a result, he has many different Targetmaster head/camshaft/induction combinations. The engine seen here was destined for a four-speed Chevelle with 4.10:1 12-bolt differential, soft rubber rear tires, headers and turbo mufflers. The owner didn’t want to hurt the engine in any way, but he did not want to leave any power potential on the engine bench, either. Sherman suggested his “445 hp at 6,000 rpm and 432 lb-ft of torque” Targetmaster 350. (For the record, he also builds a series of 383ci small blocks that produce 430 hp to 450-plus horsepower, for a higher price.)

Joe Sherman suggested Edelbrock Performer RPM aluminum heads for this 445hp 350. Cast from A356-grade aluminum, the part number is 6089 and the casting number is 6088. The heads are Edelbrock heat-treated to T6 specifications. These are 64cc heads with straight spark plug threads, not angled. Many other street and race heads are available for both small- and big-block Chevy engines.

Sherman port-matched the intake ports to the intake manifold gaskets. Any mismatch would otherwise cost power and efficiency.

The Edelbrock aluminum heads are top quality. These are cast at the Edelbrock foundry, of course. This way, immense quality control is assured. The stainless steel valves come swirl-polished to aid flow and fight carbon buildup. Each combustion chamber is 64 cc.

One of the slickest intake manifolds to come down the pike is this Performer RPM Air Gap aluminum, 180-degree manifold from Edelbrock. The plenum and runners are separate from the valley cover, so the mixture runs cooler. As such, it will be denser and there will be greater cylinder filling. This means more power and engine efficiency.

This intake manifold is drilled for a Holley-type carburetor gasket and baseplate. Other carbs with dual-drilled baseplates will fit. Being 180-degree designed, the plenum is cut in half. Each side feeds four cylinders. This benefits low- and mid-range torque and throttle response. Since the upper portion of the plenum divider is not there, increased upper-rpm cylinder filling can be accomplished if needed.

Sherman chose a Comp Cams 0.490-inch-lift hydraulic camshaft. With a split 274/286 duration, the cam makes good torque and horsepower to 6,000 rpm. The part number is 12-246-3 and the grind number is CS-XE274H-10.

Here is the Comp Cams data, also known as the cam card. When you buy a cam or an engine, do not throw away or misplace the cam card. Create an engine data folder for all receipts and data, such as the cam card.

Here is one of the Edelbrock high-flow, D-shaped exhaust ports and the “straight” spark plug threads. Everything is high tech and first class. With the advent of today’s heads, Sherman said that “angled” spark plugs are no longer necessary.

We were amazed that Sherman could coax another 195 hp from a 250hp 350 Targetmaster. How would he and assistant John McKinley do it? We made three trips to his shop to find out. The first trip was to watch the original engine being disassembled, the second was to witness its modifications and reassembly, and on our third trip we saw it perform on Sherman Racing’s Superflow computer-controlled engine dynamometer.

Sherman has so many combinations that we cannot begin to list them all. By talking to a buyer, he can dial in to the absolutely correct combination, both power-wise and cost-wise. Will he reveal this information over the telephone to anyone reading this story? Not likely. This is his livelihood. Sometimes he will charge a fee of $300 to list an entire engine combination for someone who, for some reason, cannot buy from him. He is available to talk to you about your engine problems, but only if it concerns buying his engine.

Item No. 1: Pistons/Compression Ratio

Here is the short block with KB pistons. These blocks have a tall deck height, so the piston top sits well below it. Therefore, this 11.0:1-compression piston figures out to be about 10.6:1. Great for a performance pump-gas engine.

Sherman let us know that the new Targetmaster 350 blocks are tall.

The cast-aluminum dish piston sits “a bunch” below the deck. This means a compression ratio of 8.5:1 or less. Speaking from vast experience, small-block Chevy V-8s do not like a compression ratio this low. Overall efficiency, even with a smooth-idle camshaft, is impossible to generate.

Sherman decided to fit this engine with a Keith Black domed, forged-aluminum piston. In a 0-deck-height block, it would have an 11.0:1 compression ratio. But well below deck height, the compression ratio would be about 10.6:1. Perfect, Sherman says, for a street/strip performance engine running pump gas.

Item No. 2: Heads/Induction Combination

The cast-iron Targetmaster heads feature medium ports. By comparison, they are down 40 hp to 50 hp compared to what’s available in both aluminum and cast iron. Valve pocket porting can gain back 20 hp to 25 hp. For the most part, Sherman shies away from the Targetmaster heads in favor of factory Vortec heads, World Products iron heads or aluminum heads. In this case, he used Edelbrock PN 6089 (casting number 6088) Performer RPM heads. Port matching is done, but not much more, unless the owner so

Here is one Keith Black piston hung on a Targetmaster rod. The pistons were balanced, as were all eight rods and the crankshaft.

desires.

In short, Sherman discusses with the customer at length what he wants to accomplish. Then he explains the exact buildup as he sees it. Nothing is left to chance, except for the carburetor. Sherman does not include one. Customers often have their own or something in mind, so they are not forced to buy one with his combination. He will, of course, sell you one individually if you choose.

Joe Sherman Racing offers intake manifolds for every type of driving and performance need. He makes exact recommendations based on the overall combination. This Targetmaster 350 was to be equipped with an Edelbrock Performer RPM Air Gap manifold. It is a 180-degree manifold, so it has good, low-rpm throttle response. Its features were designed to help create great torque and horsepower across the entire rpm scale. This Targetmaster engine comes with a nodular-iron crankshaft, so Sherman says its rev limit should be 6,000 rpm.

The new camshaft’s distributor gears and cam lobes were coated with break-in lube. The first few minutes of engine run-in are the most critical, and the lube helps the cam lobes and lifter faces find a perfect marriage.

Interestingly, all 16 hydraulic lifters were coated with break-in lube. Joe Sherman Racing leaves nothing to chance.

Sealing an aluminum-head engine requires a special head gasket. This engine has Victor Reinz Nitroseal composite head gaskets, no. 5746.

The first Edelbrock head was set on the short block. Next, the aftermarket head bolts were coated and installed by hand. A three-sequence torque-down came last. A special method from the center bolt out is a must-do, so consult a repair manual.

Here is the hardened Edelbrock pushrod guideplate and two 7/16-inch screw-in studs. Standard studs are 3/8 inch, but the owner wanted larger studs.

Item No. 3: Camshaft

The only way to rotate the reciprocals is with something like a B&B Performance crankshaft socket and your 1/2-inch drive ratchet. The socket slides onto the crankshaft and anchors onto the keyway.

Take your pick—there are dozens from which to choose, and from many manufacturers. Many believe bigger is better, but if you don’t have the exhaust system, torque-converter stall speed and gear ratio, you may just shoot yourself in the foot. For a 445hp (at 6,000 rpm) 350 with high-flow Edelbrock aluminum heads and Performer Plus Air Gap intake manifold, Sherman chose a camshaft he has already had plenty of good luck with, dollar for dollar and all things considered. It’s a Comp Cams hydraulic (PN 12-246-3). The grind number is CS-XE274H-10. Its valve lift is 0.490 inch on the intake and exhaust and the duration is split, 274 degrees on the intake and 286 degrees in the exhaust.

Because the 3/8-inch screw-in studs were replaced with 7/16-inch units, you must realign the pushrod guideplates. First, have the studs hand-tight; then install a pair of pushrods. Eyeball the side clearance on each guideplate slot and then snug down the studs with a long socket. Lastly, torque to spec and you are done.

In case you did not know, factory high-performance valve springs and most head pads can handle a cam with 0.499-inch valve lift. At 0.500 inch or more, coil bind sets in. So this cam does not require bigger springs or any spring pad milling. But if you choose 1.6 rocker arms, you’ll need bigger valve springs, as the total lift will be 0.523 inch.

Item No. 4: Roller Rocker Arms

Sherman believes in full roller rocker arms to help reduce friction and possible high-rpm rocker arm instability. Comp Cams’ 1.6-ratio units got the nod here. Earlier tests reveal a 16hp gain compared to 1.5-ratio units. That’s 2 hp per cylinder, which is not bad.

To check for correct valvetrain geometry, the valve-stem tips are marked and then the engine is rotated one revolution with the rocker arms installed. The valve tips are then inspected for exact center positioning with the roller rocker arm tip. If the mark is above or below the centerline, adjustments must be made; otherwise premature valve-stem and valve-guide wear will occur. As we watched, all valve tips came up center-perfect.

Another test Joe Sherman Racing does is the rocker-arm tip-to-valve-stem tip positioning. If the rocker arm is not perfectly centered in the middle, premature valve-stem and valve-guide wear will occur.

This valve-stem tip is an example of what all 16 looked like after being tested. The line directly across the middle is where the roller rocker arm pushed downward onto the valve.

John McKinley has installed the stock oil pump and is about to coat the hold- down bolt threads and then torque to spec. Also note the oil filter hole. There is no adapter for a screw-on canister. McKinley bought an aftermarket assembly and will soon install it.

Silicone sealer is used sparingly at each corner where the front and rear rubber seals meet the cork pan gasket. Because of crankcase pressure, engines have always leaked a little oil over time from these corners. Not anymore.

Here is the aftermarket oil filter adapter, less one of the two hold-down bolts.

An automatic-transmission flexplate or standard-transmission flywheel, as well as a harmonic balancer, do not come with the Targetmaster engine from GM. Sherman suggests either the GM 6-3/4-inch or 8-inch balancer. The cost difference is about $3, so he prefers the larger unit. The balancer removes slight harmonics within the crankshaft. Supposedly, the bigger the balancer, the better. We ran a 283 balancer on a roller-cammed 327 for years with no problems.

Item No. 5: Oiling

Firing the engine on the Superflow dynamometer was an MSD HEI-type distributor, spark plug wires and coil. It never missed a beat.

Unless the customer chooses otherwise, the original factory 5-quart oil pan and stock oil pump are used. We noted with interest the factory oil pan rail reinforcement bars. They distribute bolt torque and do much to eliminate gasket leaks. Sherman uses a dab of silicone sealer at each corner where the front and rear rubber gaskets meet the left and right cork gaskets.

Joe Sherman Racing’s dyno headers featured 1-3/4-inch primary pipes, since he builds a lot of killer engines. Sherman believes they cost the engine some power in the mid-range, but the 445 hp at 6,000 rpm was pretty accurate. When choosing headers, make sure they have plenty of spark plug boot clearance. Most do, but a few do not.

Seen here is a brand-new Targetmaster 350 crate engine from GM Performance Parts, with Joe Sherman Racing’s personal-touch upgrades. The icing on the cake is Sherman’s assurance that his modified Targetmaster engines are all “extremely reliable.” We always take note of an engine’s torque output and torque curve. Sherman’s dyno test began at 4,000 rpm and ended

at 6,300 rpm. From the base rpm to 6,000 rpm, the torque output dropped only 29 lb-ft (421 to 390). Horsepower increased from 321 at 4,000 rpm to 445 at 6,000 rpm. The original Targetmaster would have registered about 250 hp at 4,000 rpm and no more. Joe Sherman Racing’s select bolt-on aftermarket parts combination makes for one impressive pump-gas street engine.

Additional 195 hp

Starting With a 250hp Replacement Engine, Joe Sherman Racing Adds an Additional 195 hp

Some time ago, Chevrolet began lowering engine compression (to 8.50:1) in an effort to meet tailpipe emissions numbers. It also retarded camshaft timing in an effort to lower NOX (nitrides of oxygen/unburned particulates).