1976 Chevy Camaro - Project g/28 Part 4
Our '76 Camaro will live in the real world with a bolt-together smog-legal 400hp 383 from Speed-O-Motive.
From the January, 2009 issue of Popular Hot Rodding
All contributors: Steve Dulcich
Out west, any passenger car manufactured after 1975 is subject to bi-annual emission inspections, and "the man" is very interested in the hardware under the hood. Our project g/28, the 1976 Camaro project we've been building over the last few issues, definitely falls under the category of an emissions parolee. Our Camaro is bound by law to check in with the smog inspection authorities every two years, where they decide whether it's staying clean and can be allowed free amongst the general population. Give in to temptation and step outside the terms set down by the Board, and the Warden will drop the hammer and take it off the streets. We like to avoid the crack of the gavel when we can.
Out here we have something we consider frontier justice, a sense of propriety and fairness that forms a code of its own. In the days of the Old West, Judge Roy Bean was the law west of the Pecos River, deciding on common sense and logic what is right, the codes and law books be dammed. Our g/28 would have to have a hot mill, yeah hot enough to stand out as a rowdy outlaw, but enough inside the law not to get hanged. We had no doubt that the engine we'd build would burn clean. We'd have no problem consenting to a sniff of the pipe--our engines normally have nothing to hide from the smog station sobriety patrol. Clean or not, the equipment must also get past the official visual shakedown. The fact is that by strict interpretation of the codes, we doubt our engine meets every letter of the law. As long as it burns clean, and externally carries the required exempt and legal components, our sense of frontier justice will be satisfied. More importantly, we are fairly secure that it would earn a reprieve in view of the critical eye of the authorities.
Project g/28 was originally equipped with a small-block 305, a mill too light on displacement and too scrawny in bore size to be practical as a street thug in a heavy Camaro. The obvious scheme was to juice the bottom end, bulking-up illicit muscle with a doping of displacement. The goodfella big small-block in the Chevy world has long been the 383 combo, a street savvy balance of size, torque potential, durability, and practicality. The extra 78 cubes the g/28 will be packing are easily smuggled inside a stock-looking block, and will stash a heavy load of useable torque. We planned our bottom end job around a production four-bolt 350 block, and packed the heat in the form of Lunati's new 383 "Sledgehammer" rotating assembly.
The Lunati hardware includes the US-manufactured "Sledgehammer" 4340 forged non-twist forged steel crank, which is made tougher by nitriding. Adding to the strength of the set-up are bulletproof forged 4340 I-beam rods with capscrew fasteners and forged 4032 alloy flat-top slugs, all equipment tough enough to take a beating without squealing. In fact, it might be said that the Lunati equipment we selected for this application is too hardcore for our final output goals of just over 400 real street horsepower. In reality, the Lunati bottom- end can easily handle far more threatening power levels. Why the extra-tough components? We want the backup in place downstairs if the situation calls for it. Besides, the Sledgehammer crank is surprisingly affordable (around $800 at going mail order prices) so why not? Yeah, the world of Popular Hot Rodding can be a dangerous place for an engine's guts, a minefield of all-out high-rpm road-course track time, dragstrip punishment, not to mention the seduction of experimenting with injected nitrous oxide. We had little doubt that the Lunati equipment would cover our backs no matter what we later threw at the engine. The "Sledgehammer" kit came internally balanced, and is supplied with the full swag, including ductile iron moly rings and alecular bearings.
Lunati's kit had the inside angle covered, but our moves on the outside would be more open to scrutiny. Here, the obstacle is making it through the watchful eye of the visual inspection without ending up busted, and the prospects are limiting. No matter how clean the actual emissions might be, if the equipment doesn't have a C.A.R.B. (California Air Resources Board) E.O. number (Exemption Order) expect to be slammed. We really didn't want to go through smog testing with a lump in our throat like an illegal without the requisite papers making a border crossing, so here we wanted to go legit. Holley's 50-state legal SysteMAX combo, PN 300-504-1, made it easy to walk that tightrope, with the E.O. documents to prove it. The SysteMAX cam/heads/intake package includes an emissions-legal camshaft and components (CARB E.O. No. D-115-10). Though the camshaft will blow under the legal limit, the specs are well beyond meek OE small-block smog cams. The mug shot shows an intake duration of 272/284 degrees (216/228 degrees at 0.050 inch), and 0.454/0.480-inch lift on the intake and exhaust lobe, respectively. Lobe separation measures a smooth 112 degrees. Supporting the cam kit, Lunati components were used throughout, with 1.5:1 aluminum roller rockers, a double-roller timing set, and the required pushrods. Up top, PN 300-522-1 cylinder heads are also smog-legal (CARB E.O. No. D-115-8), and post an intake flow of 223 cfm through 184cc ports, and 173 cfm on the exhaust side, with the readings taken at a realistic .500-inch lift. To finish the emissions-legal package, an Weiand two-plane intake (CARB E.O. No. D-265) gets the okay, kept legal with an E.O. 600-cfm Holley No. 80451 vacuum secondary carb.
We took our smog-legal small-block scheme to Speed-O-Motive, and they too were intrigued with the prospect of a torquey 400hp stealth stroker that could run clean and pass a visual inspection in a carbureted application. The SysteMAX components and the 600-cfm 4160 carburetor are exempt for a wide range of pre-1986 applications, with a detailed listing available at Holley.com. With so many potential hot street machines falling under the long arm of the inspector, a combo that can make real power while keeping the law at bay certainly has its appeal. Speed-O-Motive handled the machining and assembly of the engine, filling out the remainder of parts list with a mix of their in-house product lines, and bolted it all together with fasteners from ARP and a complete HEI ignition from MSD. Despite the long list of custom parts, the engine was very cooperative when it went together. The matched aftermarket Holley parts bolted up like the stockers.
On the dyno day, we were eager to see if the 383 could deliver brutish street power levels, even with the mild, emissions-friendly, parts. Sure, you might think running smog-legal is like making a break for the fence in leg irons, but the 383 cracked the 400hp mark, clearing 403 hp at 5,400 rpm, with Speed-O-Motive's tuning of the carb and ignition. While the power level met the mark we were hoping for, torque came on like a bully, twisting the dyno's torque arm to the 416 lb-ft mark right at the bottom of our pull at 2,400 rpm, and laying down 450 lb-ft of torque at the peak. Torque will litter the pavement when this mill comes into town. This 383 combo has the manners you can live with every day without feeling abused, idling nicely at 750 rpm--but stab the throttle at any rpm, and the ferocious torque will punch you right back. Want one? Speed-O-Motive sells this 383 as a package, built for $7495, turn-key, and dyno tested; including the flex plate and damper.
We plan on stabbing our smog-legal Speed-O-Motive 383 into g/28 in the coming weeks, mating it to one of TCI's bulletproof Turbo 350 transmissions. That TH350 will have a manual reverse-pattern valve body for hand-to-hand combat in road racing and it will be coupled to TCI's Breakaway converter and new StreetFighter shifter. We like shifting manually, especially on a road course, so this ought to be one simple yet tough combo that won't let us down. Once we get that done, we'll strap g/28 on the chassis dyno and see how well our combo does at the rear wheels.
We've still got to get our Nitto R-compound DOT tires on some 17x9-inch rims, and we think we may have found the answer in the form of American Racing's new Rebel one-piece wheel. If they work out like we think, they'll cost even less than the Weld Pro-Star XPs, which are no longer being built. We're also working on a 14:1 steering box upgrade from Flaming River and some better, more supportive seats from Jeg's. Lots more affordable performance is coming down the pipeline for Project g/28, so stay tuned!
All of that aluminum and a...
All of that aluminum and a Holley carb will normally bring on the shackles from an emissions inspector, but with Lunati and Holley emissions-exempt parts, Project g/28 can leave by the front door and they'll even let us drive it home.
Bigger torque and power from...
Bigger torque and power from a 350 small-block Chevy are readily up for grabs with a Lunati 383 stroker rotating assembly. The kit centers around an American forged 4340 steel "Sledgehammer" 3.750-inch stroke crank, and is filled out with Lunati's Street Race 4340 forged I-beam 6-inch rods and stroker flat-top forged pistons. Moly ductile rings and alecular bearings are part of the package, which came to us internally balanced and ready to assemble from Lunati.
The pistons in our Lunati...
The pistons in our Lunati kit are forged from 4032 alloy, a mix of aluminum with a higher silicone content than full-race pistons. This material specification significantly reduces the thermal expansion, allowing tighter piston-to-wall clearances, and quieter running, especially when cold. The valve pockets are extra deep, and provide the clearance to swallow much more lift and duration than our emission cam will deliver. The combination of this piston and the SysteMAX heads 68cc chambers provides a compression ratio of 10.6:1 at zero deck.
Holley's SysteMAX package,...
Holley's SysteMAX package, No. 300-504-1 is the key to our emissions-legal status. The kit centers around the SysteMAX E.O. heads, issued an exemption order by the California Air Resources Board, making them 50-states legal. The SysteMAX includes a complete camshaft package, also exempt, with a camshaft, lifters, timing set, and pushrods. A legal four-barrel Weiand intake completes the law-abiding set.
The Weiand aluminum two-plane...
The Weiand aluminum two-plane four-barrel intake manifold will take either a square or spread bore carb, and is equipped with EGR provisions in keeping with its smog-exempt requirements.
Some readers might just call...
Some readers might just call us out for cheating, since the EGR port (left) was blocked with a cover plate for our testing. However, EGR is vacuum operated, and remains completely shut at wide-open-throttle, which is how the dyno tests for power. No cheating here. The other port (right) is for a thermostatic choke, and is not used with the electric choke on our carb. Note the hole in the manifold plenum; this is where the exhaust gas enters the induction system when the EGR valve is open.
Even though our 383 was built...
Even though our 383 was built with the street in mind, for track duty an SFI-rated and approved damper is a requirement with some sanctioning organizations. The Professional Products unit that was bolted to our 383 meets the certification, and is economically priced. We liked the big, bold, easy-to-read timing degree marks.
We opted for a set of Lunati...
We opted for a set of Lunati aluminum roller rockers to complete the valvetrain. The ratio is stock at 1.5:1, and working with the SysteMAX smog-legal cam gives 0.454 inch of intake valve lift and 0.480 inch on the exhaust side.
For the street, we will run...
For the street, we will run a high-flow Weiand aluminum water pump, but for dyno duty, we went with the Meziere electric pump to facilitate the set-up and simplify the job.
MSD provided the billet HEI...
MSD provided the billet HEI distributor that made our ignition system. This distributor features vacuum advance, an important component in meeting emissions and economy goals. With it in place, we will not need a stand-alone ignition box, making our engine compartment a clean-looking affair.
Dyno operator, Jake Hairston,...
Dyno operator, Jake Hairston, at Speedo-O-Motive had our 383 mounted up in no time, thanks to the docking cart system of the DTS dyno. Numerous hook-ups are required to get it ready to run, including the cooling, fuel, and exhaust system, as well as multiple connections to feed information into the dyno computer.
Once ready to run, the 383...
Once ready to run, the 383 crackled to life almost instantly, and the first job was to set the rpms up to about 2,500 rpm for a cam break-in with the flat tappet camshaft. A check is made to ensure that the timing was at a safe, conservative, level. Jake set it to 32 degrees for run-in.
You won't go amiss pulling...
You won't go amiss pulling the valve covers for an inspection of the valvetrain after break-in, even when running a hydraulic cam. With a solid lifter cam the lash needs to be checked and reset hot as necessary, while a visual inspection and check of the polylocks will do with a hydraulic set-up. Everything was perfect with our Lunati valvetrain.