My First Stroker Part 3 - LS1 Engine Build

Our garage-built 383 gets its final parts installations, making this stroked LS1 ready to run!

Chris Werner Nov 1, 2006 0 Comment(s)

Step By Step

We chose to go along with the firing order of the LS1 engine (1-8-7-2-6-5-4-3) but you can go in whatever order you'd like; just don't confuse which rockers have already been bolted on and adjusted! For cylinders where you can't see the lifters (3, 5, 4, 6) it's hard to know when they're on the cam's base circle, so you'll need to spin the engine and watch the pushrods and/or rockers move (noting again that pushrods without rockers won't go down without pressure on them due to the GM lifter trays holding the lifters up).

Watch for any minor interference issues as you go through the process of installing and adjusting the rockers. When bolting on the rocker assembly for cylinder seven (driver's side rear), we found the exhaust rocker was in close proximity to the head's valve cover rail. The area was meticulously masked off and lightly ground with a die grinder, with care being taken not to go so far as to potentially affect the sealing of the valve cover gasket. With the rocker assembly reinstalled, the engine is spun over to make sure no interference exists at any point in the rocker's range of motion. Success!

The remainder of the rocker assemblies were bolted on and adjusted without problem, and the installed Jesel J2K Shaft Rocker System looks just as good here as it does under the hood of the C6R. You'll note in this final photo that we've masked off all the intake and exhaust ports; with the valves now operational, we don't want anything accidentally falling into a port and finding its way inside a cylinder-necessitating head removal (both of the cylinder, and perhaps that of the clumsy perpetrator)!

The valley cover includes provisions for the LS1's two knock sensors to be isolated from the oily engine interior. GM recommends that new knock sensor grommets be installed in the valley cover ($3.41 for a set of 5, PN 12558177), which we do here after knocking the old ones out with a socket and hammer. They're lightly lubed with oil before installation.

Here's a look at the LS1's driver side (bottom) and passenger side (top) valve covers. One can see the PCV baffling located on the underside of each, which in our case prevented them from being reinstalled as-is. A good bit of material removal, trial-fitting, followed by more material removal will be required until the valve covers will fit. We've got our fingers crossed!

The underside of the driver side valve cover has a stamped metal baffling piece running along its top edge, which the adjusters of our rocker arms bashed right into. It comes off by a light grind of the aluminum tabs holding it down, followed by simply yanking it out.

Many of the cast-in aluminum tabs that held the metal baffling to the underside of the driver side cover will need to be ground away, and most significantly, the far rear rocker (number seven exhaust) interferes heavily since the cover sits lower here in the vicinity of the PCV system grommet. Significant grinding had to be done, but we were very cautious not to go too far and break through to the outside, rendering our valve cover useless (save for a possible JB Weld fix).

As to the passenger side valve cover, things aren't as bad; in fact, none of the aluminum underside of it actually hit the rocker arms. Rather, the black plastic baffling-and aluminum vanes holding them-jut very deep and hit the actual shafts of the rocker system. It's a simply matter of snapping off the plastic, then cutting and breaking out the aluminum vanes, as shown here.

Rock and Roll, MoHawk and all: Jesel's J2K Rocker Arm System

Theoretically, you can pick up a set of rocker arms for your LS1 for a few hundred dollars-or even reuse the stockers if you're brave. But before getting yourself up in arms (no pun intended) about the price of a Jesel shaft rocker system, know this: it'll help your engine last longer, operate more safely, and make more horsepower. Sound like a lot to expect from a rocker arm set? It is-and Jesel delivers. Rocker arm design is a complex science, but we'll try and hit the highlights so that you can make an informed buying decision regarding your next set of rockers.

Stud-mount rockers have been a part of the small-block "Chevrolet" since the very beginning, and the Gen III continues the tradition. As we have stressed many times over, GM engineers did one helluva job on the factory LS1, and their design choices resulted in an engine with nary a fault. But despite all the modern technology they incorporated, one area they didn't change much was the old-school stud-mount rocker system. More than likely, the bean counters upstairs just wouldn't allow a better, more-costly-to-manufacture design through their stingy hands. The engineers did the best they could and came up with a single-plane geometry for the valve, rocker, and pushrod, as well as a stand mounting system and rollerized fulcrum for the rocker itself. The result is a valvetrain that has overall performed admirably for the emissions-friendly, low-lift camshafts of factory engines-despite some reported dark spots of bent pushrods and broken rocker arms. The problem arises in that stock-style stud rockers simply can't stand up to the demands of greater engine speeds and valvespring pressures without incurring the above-mentioned penalties in engine longevity and power production. We spoke to Jesel's Rob Remesi about the advantages his company's shaft rockers provide.

"When the Chevrolet small-block V-8 was introduced in 1955, one of its most highly touted features was its lightweight, high-revving ball and stud stamped steel rocker design," says Remesi. "This stud rocker setup served performance and racing enthusiasts for years before it became overstressed and Band-Aids started to appear. The first modification made was to install polylocks, which allowed one to maintain valve lash longer and adjust the hydraulic lifters so that they didn't pump up at high rpm. Then, as more aggressive cam profiles surfaced and valvespring pressures increased, press-in studs started pulling out of their bosses. Chevy came out with screw-in studs that didn't pull out, but their small diameter allowed them to flex too much. The fix was larger screw-in studs made out of stronger alloys. But as spring pressures continued to escalate, they too would flex, so stud girdles were invented to tie all of the studs together, mimicking the solid shaft-type rockers found on Chevy's sister division engines like Cadillac and Buick.

"Many engine builders are still struggling today with stud rockers, girdles and polylocks-antiquated parts that have no place in a modern performance engine. Dan Jesel started his company to provide the best quality rocker systems for the performance racing industry as well as the weekend warrior, and he is credited with inventing the first effective aftermarket shaft rocker system. He designed stands that bolted to the standard stud bosses, yet relocated the rocker pivot point any distance he desired away from the valves. That's the crux of the entire stud versus shaft debate-you can't change the rocker pivot length and correct the rocker geometry unless you move the pivot point. So, no stud rocker can perform as well and as reliably as a longer pivot shaft rocker-it's that simple. Shaft rockers are more stable at high rpm-ensuring accurate valve timing events-and are mounted to the head using a steel stand that positions the roller directly over the valve tip. Meanwhile, a stud rocker is aligned by the stud location and the pushrod and guide plate (as applicable)-not the best for holding the rocker where it is supposed to be-resulting in additional frictional losses. Reduced valvetrain friction equals more power and longer component life, regardless of valve lift or rocker ratio," says Remesi.

Jesel's J2K series is the latest and greatest iteration of the company's technology. The rockers' so-called MoHawk beam is claimed to be the lightest and strongest rocker design on the market, resulting in the lowest possible moment of inertia (a measure of how much of an object's mass is actually in motion as it moves or pivots). This not only increases the rpm an engine is capable of, but also lengthens valvespring life. "The components used in our rocker set for the ET Performance LS1 heads are the same components that we used to build the rockers for the Katech-built C6R engine that just won the 24 hours of LeMans," says Remesi. "When a rocker set is shipped from our facility, we don't know whether it is going to be used on a race engine or a street engine. There is nothing better than on-track testing to prove the durability of engine components; you can rest easy knowing the same Jesel parts that are going into your street LS1 have just been proven in one of the world's most grueling endurance races!"

Hopefully, you can start to see that when you weigh in the benefits a Jesel shaft rocker system provides to your engine, the investment is a darn good one.

We Have Ignition!

When introduced in the 1997 Corvette, the LS1 featured many major changes from past small-block engines, and one of the most significant was its coil-near-plug ignition system. After the LT1's notorious OptiSpark featured just the previous model year, the LS1's one-coil-per-cylinder system was no less than a revolution in terms of GM V-8 ignition. But like all things found under the hood of a GM performance car, we love to modify and improve-no matter how good any one factory system might be. That said, upgrades are available on the market to make the LS1's ignition system perform even better.

By definition, for an equivalent displacement engine to make more horsepower, you must increase cylinder pressures. Hi-po parts like better-flowing cylinder heads, large-runner intakes, and wilder cams all help jam more oxygen and gasoline into the cylinder, which, when lit, create the enormous spike in pressure that presses down on the top of the piston, twists the crank, and sends torque to your rear wheels. But the denser the air-fuel charge is, the more difficult it is to properly ignite-and adding nitrous oxide to the mix only compounds the problem. This science holds equally true whether you're dealing with a stock-displacement engine or a stroker motor like ours.

One of the major players offering components to up the output of Gen III ignition systems is MSD. The company now offers higher-output coils to further enhance the LS1's fuel-mix-igniting ability. Here are the coil specs for all you techno-freaks out there: a turns ratio of 52 to 1 acts with a primary resistance of 0.57 ohms and a secondary resistance of 3,100 ohms to yield a peak current output of 150 milliamps. Combined with a spark duration of 1.2 milliseconds and a maximum voltage of 44,000 volts, these coils purportedly put out three times the spark energy of the stock ones. But let's not forget that these coils also produce the multiple sparks from which MSD Ignition takes its name. According to MSD's Todd Ryden, "the multiple sparks don't necessarily increase horsepower, but add significantly to the drivability aspect of the vehicle. They help provide a good idle, quick throttle response, and will also assist in supercharged or nitrous applications." Lower emissions and increased fuel mileage are certainly no bad thing, and MSD's system helps ensure a complete burn of the air/fuel mix under any engine condition imaginable.

The perfect complement to these coils are MSD's Super Conductor plug wires, which spec out at less than 50 ohms per foot (factory wires are normally in the vicinity of 1,000 ohms per foot); so very little energy is lost as current travels to the plug. Despite this small resistance value, MSD's special winding procedure for the copper alloy conductor and its ferro-magnetic impregnated core yields only a tiny fraction of the electromagnetic interference (EMI) emitted by other aftermarket wires-shielding your radio and other devices from static. The wires also feature a dual-crimp terminal and use a proprietary silicone/synthetic-blend boot material for the ultimate in strength and heat resistance.

With products from MSD guaranteeing a powerful spark under all operating conditions, we have no worries about our ignition system being ready, willing, and able to light some serious fires within the bores of our 383 LS1!




subscribe to the magazine

get digital get print