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Project American Heroes II Unveiling at the Joliet Super Chevy Show
When we started mulling over what mill to stuff under the hood of our Project American Heroes '69 Camaro, we knew it had to be something special. After all, this ride was being built as a tribute to the men and women in our armed services, so nothing wimpy or yawn-inducing would suffice. It needed to be civilized and refined when cruising, yet capable of laying some serious hurt when needed.
Our first idea was to go with a big-block. After all, that would certainly get us some snappy power levels, but the weight penalty wouldn't help handling, and big-blocks are known for being pretty thirsty at the pump. A small-block would solve the weight issue, but the loss of displacement would hurt the performance numbers. Then it hit us. What we needed was a big-inch small-block.
And because losing weight is just as good as making more power, we decided that the engine should be as light as possible. After talking it over with Kory Enger of Turn Key Engine Supply in Oceanside, California, we pulled the trigger on running a 427-cubic-inch (427.7, to be exact) LS7-based engine. This way we could have it all: big-block displacement, fuel-sipping EFI, and lightweight aluminum architecture.
The first step was sourcing a seven-liter LS7 block. This turned out to be the toughest part of the build since nobody seemed to have one in stock. Luckily, we were smart enough to call LS-guru and fourth-gen Camaro aficionado Matt Murphy of GMMG. He dug deep into his black book, made some calls, and managed to find us a virgin aluminum block hiding in Texas. Even better, he donated it to the cause!
For a rotating assembly, Lunati stepped up to the plate with its top-of-the-line Pro-Series crank, rods, and Wiseco forged pistons. Chris Douglas, of Comp Cams, hooked us up with all of our valvetrain components and tossed in a set of massaged Racing Head Service (RHS) Gen-III 225cc heads. Topping it all off is a Weiand intake from Bill Tichenor over at Holley.
This Lunati Pro Series forged crank (four-inch stroke, PN J0711ER) will handle anything we throw at it. It's American made from the highest quality 4340 steel, and each rod journal is drilled with a Y-inch or O-inch lightening hole to reduce inertia weight. Even though all LS7 GM engines run a 58-tooth reluctor wheel, Turn Key had us order the crank with a 24x wheel. This will make programming and tuning the 427 LS engine a snap
With a huge stack of parts loaded in the back of our truck, we headed over to Turn Key Engine Supply, which was donating its considerable skills-and more than a few parts-to getting this engine fired up and ready to power our '69 Camaro.
GM spends a ton of cash developing parts, so in many cases there's no need to go exotic. In this case, Turn Key chose a GM timing chain and a ported LS6 oil pump. Many people feel the overwhelming need to run a double-roller timing chain, but in many cases it's overkill. Even GM's new supercharged LS9 runs a single-roller arrangement.
With the crank and cam installed, Turn Key moved on to carefully installing the pistons. The cylinder walls were liberally lubricated before the pistons were slid into the bores using the appropriate ring compressor.
For a bumpstick, we had Comp custom grind us a cam to Turn Key's specifications. Drivability was as important as making big numbers, so Turn Key went with one of its proven LS7 grinds. The specs are 230/242 with lift numbers of .572/.593 and a lobe separation angle of 114. This should give us great idle characteristics and still make gobs of tire-immolating power.
After file-fitting the Wiseco rings, Turn Key assembled the rods and pistons. The 4340 I-beam Lunati rods (6.125-inch length, PN 6125FM3) comes matched to +/- 1.5 grams and utilizes ARP cap hardware. Rods take a lot of abuse, so it's nice to know we're running the best. The pistons, provided by Lunati, are Wiseco Pro-Tru slugs (PN WISK446F125) and are forged from 2618 aluminum.
Once all the pistons and rods were in place, the ARP bolts were properly torqued to spec.
With the windage tray and pickup in place, Turn Key was then able to install the F-body GM oil pan. Pan alignment with the front and rear covers is critical to avoiding any oil leaks, so Turn Key made sure it was done right the first time.
RHS sent over these sweet Pro Elite series Gen-III heads (PN52225-05) for the project. They came fully CNC-machined and have a thick 0.800-inch deck for increased structural integrity. These heads just scream for forced induction or a nice shot of nitrous, so they should be virtually bulletproof on our naturally aspirated mill. Another benefit of the increased deck thickness is the heads can be decked down to 36cc for increased compression, but our goal is good pump gas manners, so we left them at 62cc. Also of note is that Racing Head Service (RHS) has re-engineered the valve placement by rolling them over 4 degrees from stock to create an 11-degree valve angle. This helps accommodate high lift cams by creating additional free drop spacing.
For the 427 to fit in the '69 Camaro, we needed to run an F-body oil pan rather than the more exotic LS7 dry sump system. Here you can see the F-body windage tray and pick-up bolted in place. Notice the liberal use of marking paint by Turn Key to insure than every bolt has been properly torqued down.
Here you can get a good view of the business side of the Weisco pistons provided by Lunati. The -15cc dish will yield us a very pump gas-friendly 10:1 compression ratio.
With the Fel-Pro gasket in place, the RHS cylinder head was carefully lowered into position. Once in place, it was secured using ARP bolts liberally swathed in assembly lube.
The only downside to running the sexy shaft-mounted rockers was that the factory valve covers would no longer fit. Luckily Turn Key had these sweet billet spacers on hand to save the day. They incorporate the same gasket as the GM valve covers, so they're easy to install and will be leak-free.
With the Weiand intake, GM fuel rails, 46-pound injectors, and coil packs installed, our 427 small-block is ready for its date with the dyno at Westech Performance.
Given how bulletproof the rest of our engine was, we didn't want to cheap-out on the rockers, so we went with Comp's shaft-mounted aluminum units (PN1500). These rockers feature 8629 steel pedestals with shafts that have been deep case-hardened and tempered for max strength. The benefit of the shaft arrangement is that it provides a stable and accurate pivot point for the 2024 aluminum 1.7-ratio rocker arm bodies. They also feature oil passages that feed pressurized oil to the shaft bearings and rollers tips. This not only extends the service life, but it provides a continuous stream of cooling oil to the valve springs.
Another issue arose when we went to bolt the Weiand aluminum intake on top of the LS2 valley cover. The Weiand intake has been around for a few years, and General Motors has revised its valley covers to incorporate bungs for PCV fittings. We could have cut these offending bumps off the LS2 cover and welded up the holes, but Turn Key had an easier solution in the form of this flat billet valley cover that it typically uses when installing blowers. Before the '69 Camaro is finished, we will be swapping out the aluminum intake for Weiand's new 90mm composite Street Warrior intake.
Here are the brains of this operation, a GM MEFI-4 computer. It's small, but more than capable of controlling our new 427 powerplant. Turn Key also provided its five-wire hookup engine harness. Just as the name implies, this simple-to-install harness requires only five wires to be spliced into the rest of the car. This is a good thing, since time is running out to get this project on the road, and the guys at Route 66 Motorsports will appreciate the simplicity when they graft this engine into the Camaro.
With the 427 strapped down to Westech's Superflow 901 dyno, Kory could get started tuning the all-aluminum engine. Running on the 91-octane stuff they pass off in California as premium gas, the mill put down peak numbers of 562 hp at 6,200 rpm and 561 lb-ft or torque at 4,700 rpm. More important, the torque curve of the engine extends past 450 lb-ft from 3,000 rpm all the way through 6,400 rpm, and at idle it runs silky smooth.