If your car or truck has a small-block that's long in the tooth or has seen a hard life, odds are it's not running with the same pep it had when new. You might even be burning some oil and hearing a few funny noises that are cause for concern. But thanks to GM Performance Parts, giving your Chevy an injection of fresh horsepower is easier than ever.
The motor in this '92 Camaro RS was definitely showing signs of fatigue. With almost 210,000 miles on the clock, the 305 still ran OK and wasn't consuming oil, but definitely lacked whatever meager punch it had when new. There was debate about building a fresh 305 for the car, but in the end the decision was to go ahead and replace the 305 with a bigger and more powerful 350. Not to say the 305 is a bad motor, but with the future plans for this car, a 350 made more sense and gave a much higher performance ceiling.
But what 350 to replace it with? That was the question. Do you find a junkyard 350 to rebuild, build a fresh engine from all new parts, or go the crate engine route?
After a call to GM Performance Parts, we decided to put together a fresh engine from new parts. The foundation would be a ZZ4 short-block (PN 12561723), so we looked through the GMPP catalog and picked out the rest of the parts to assemble a long-block for the Camaro. The beautiful thing about this build is the engine could virtually go in any Gen I SBC-equipped car or truck. We went with the GMPP Fast Burn heads, but being a small-block Chevy, the choices are virtually limitless.
Follow along as we put everything together to give this '92 RS some much needed zip.
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When new in '92, the L03 made 170hp with throttle body injection. Its TPI equipped LB9 sibling made 205 horses. The engine ran well, with no smoke, oil consumption, or mystery noises that indicated it was on deaths door. Driving the car back from Atlanta where it was purchased, the 305 chugged out 26 mpg on the highway, running about 70-80 mph Not bad for a 17-year-old engine with a ton of miles. On a Mustang chassis dyno, though, it only sent 126 ponies to the wheels, a definite sign more power was needed.
The foundation for this engine is the stout ZZ4 short-block assembly. It features a forged crankshaft with one-piece rear main seal design, four-bolt mains, powdered metal rods, and high-silicon aluminum pistons with offset pins. The block has both side and front engine mount bosses, making it easily installed in any Chevrolet car or truck. It also features a fully machined mechanical fuel pump boss, so the engine can run either carb or fuel injection.
This short-block is a great start for any engine build, from street performance to moderate racing use. If youre new to engine assembly, dont have all the necessary tools, and your mechanical expertise is limited, play it safe and get a pre-assembled short-block, or have your local machine shop do it for you. It only takes one small mistake in short-block assembly to spell doom for an engine.
There was some packing grease built up on the short-block, so we wet down a rag with some mineral spirits to clean things up a bit. We also cleaned the tops of the pistons too.
Because of its all around performance, we stuck with the ZZ4 hydraulic roller camshaft. With a 112-degree lobe separation and 0.474-inch intake lift and 0.510-inch exhaust lift, the ZZ4 cam offers a smooth idle, great power curve, and will work with stock length small-block valves.
Before installation, the cam is wiped down with mineral spirits, dried, then engine assembly lube applied to all the lobes. The assembly lube will protect the lobes of the cam during initial startup until oil pressure builds and fully circulates oil through the engine.
To make installing the cam easier, screw a couple of long bolts into the nose of the cam so you have something to grip and keep the cam lobes from getting nicked while inserting the cam into the block.
For this engine we used factory roller lifters with the factory spider retainer. Since roller lifters don't need to rotate like flat tappet lifters, they have to have a retainer of some sort to keep them from spinning because of the rotation of the cam. Most factory setups use a stamped steel spider to hold down tabs over each pair of lifters that keeps them from spinning. Most aftermarket lifters use a crossbar design that has a linking bar between the lifters, eliminating the need for a spider retainer.
Here you can see the 'dog bone' retainers that keep the lifters from rotating in their bores. The arm of the spider has a tab the rests on the center of the dog bone to keep it in place while the lifters are operating. Since 1987, all GM small-blocks have been roller blocks, meaning theyre cast with taller lifter bores than earlier Gen I blocks to handle the tall factory-style roller lifters and they have the three holes in the center of the lifter valley to retainer the spider. Even though the Gen I Chevy truck engines didnt get factory roller cams until 1996, they used roller blocks with the tall lifter bores, so retrofitting/upgrading them with a roller cam is easy.
Before slipping each lifter into its bore, give it a coating of engine assembly lube, including the tips. Use engine assembly lube and not oil; the assembly lube's thicker viscosity will keep the oil from running off the parts before you start the engine for the first time.
With all the lifters in place, the spider retainer is set down in the valley, with the tabs lined up on the lifter retainers.
It's a good precaution to use some thread locker on the three bolts to hold the spider in place, so engine vibration doesn't loosen them up and cause the valvetrain to go crazy and eat the motor. Tighten all three bolts down, and the lifter retainers and spider are secure.
Because the ZZ4 cam has an LT1-style nose, we had to use an LT1-style timing chain. We opted for GMPP's single roller chain, which has more than enough strength to handle what we'll be doing with this engine.
The ZZ4 block comes already machined for the factory LT1 cam retainer plate. This plate keeps the roller cam from walking forward in the block. With a flat tappet cam, the spinning motion of the lifters keeps the camshaft from moving forward, but with a roller cam you need a retainer of some sort to keep the cam from moving. On a standard Gen I small-block cam/timing set, you use a button spacer to do the same thing.
For the camshaft sprocket bolts, some high-strength threadlocker is good insurance to keep the bolts from coming loose due to engine vibration. There are also special retainer tabs that go under the bolts with 'ears' that you bend back to keep the bolts from loosening also.
When installing your timing chain, make sure the dots on the cam sprocket and crank sprocket line up across from each other. If they don't, the cam will be out of phase/timing with the crankshaft and the engine will run like garbage, and possibly bend a valve or two.
Moving to the bottom of the engine, we installed a new standard-volume oil pump. Why not a high-volume pump? Most street engines have zero need for a high-volume oil pump. Usually the increased oil flow/capacity of an HV pump is only needed in racing applications. On the street, an HV pump can make too much oil pressure, which will drag down the engine, hurting power output and possibly causing damage. Unless your engine is seeing a lot of sustained high rpm operation, a standard volume oil pump is all youll need. To secure the pump, we used an ARP oil pump stud kit. Capping the bottom end off was a standard small-block oil pan from GM Performance.
With the cam and lifters installed, it's time to install the heads and top of the valvetrain. First up is the head gasket. Each gasket is stamped with "this side up" so you cant put them on the wrong way. To assemble the engine we ordered a full engine gasket kit form GM Performance's catalog.
To bolt down our GM Fast Burn heads, we used ARP's stainless head bolt kit, PN 434-3601. Why stainless? Besides the normal salt air on the Florida coast and stainless steel's corrosion resistance, we're addicted to shiny objects, and the stainless bolts have some extra pop over the normal black-oxide treated head bolts. Since some of the head bolt holes go into the water jackets, thread sealer is necessary. To play it safe we put thread sealer on all of the head bolts. To install them you'll need a good torque wrench and deep-well socket. Install all of the head bolts and just hand tighten them. After that, go back and tighten each one in sequence in a 25-50-68 lb-ft increment. So, first you'll tighten all the bolts in sequence to 25 lb-ft of torque, then 50, then 68. If you dont, you'll warp the heads and won't have proper sealing, equaling no/low compression.
Instead of ZZ4 heads, we chose to go with GMPP's Fast Burn heads, PN 12464298. They feature 210cc intake ports to the ZZ4's 163cc ports, larger 62cc combustion chamber, and has dual intake bolt patterns, so you can either use a Vortec-style manifold or a Gen I manifold with these heads.
Another advantage the Fast Burn heads have over the ZZ4s is the use of the Vortec/LT1/LT4 style combustion chamber with some tweaks to maximize combustion, resulting in higher cylinder pressures and more horsepower. They have 2.00-inch intake valves and 1.55-inch exhaust valves, screw in studs from the factory, and will use either center-bolt or perimeter-bolt valve covers.
With the heads installed, next up were the rockers and pushrods. We used GMPP's heavy wall 3/8-inch pushrods and 1.5 ratio, self-aligning aluminum roller rocker arms. You can also use the old reliable stamped steel rocker arms on these heads if necessary. Be sure when installing the pushrods to put a dab of engine assembly lube on the lifter end of the pushrod. For the rockers, put some lube on the roller tip and the pushrod adjuster cup.
Before setting lifter preload, we used a GMPP oil pump primer and electric drill to pump up the lifters to get proper preload. This also helped to pre-lube the engine and prime the oil pump.
With the lifters pumped up, we could set lifter preload. Our rocker arms came with locking adjuster nuts, so we had to back out the locking screw first. Then, while turning the pushrod by hand, tighten the adjuster nut until you can't move the pushrod. Then turn the adjuster nut a half a turn, tighten the locking screw, and you're done. The method for setting lifter pre-load is to do one cylinder at a time.
First you turn the crankshaft by hand, until the exhaust rocker/valve begins to open. When this happens, set the INTAKE lifter preload. Then turn the engine again, until the intake rocker/valve is almost closed. Stop, then set the EXHAUST lifter preload. The reason for this method is lifter preload must be set with the lifter on the base circle of the cam lobe. This how you tell when a lifter is on the base circle for intake and exhaust. Repeat this procedure for all cylinders.
With everything set it was time to button up the engine. To make it look nice but not too flashy, we went with this engine dress-up kit from GM Performance Parts in metallic gray, PN 141-360. It includes valve and timing covers, air cleaner assembly, matching valve cover hold down tabs and wing nuts, and breather cap.
Here's how the motor looks, all buttoned up and ready to go. Watch for a later story where we'll show the motor going into the '92 Camaro, and see how much power it puts out on the chassis dyno.