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Big-Block Chevy Engine Build - Project American Heroes: Shock & Awe

Project American Heroes Will Blow Away The Competition Thanks To Its 717-Horse Smeding Performance 572 Big-Block

Mike Harrington Oct 17, 2007
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On a recent trip to the all-GM show in Carlisle, Pennsylvania, the opportunity to spend several hours touring the Gettysburg battlefield site presented itself. There is an almost a reverent atmosphere here, the place where tens of thousands of men perished over the course of three days. Right or wrong, North or South, they were still American soldiers fighting for what they thought was right.

Today our American solders are embroiled in conflicts around the globe. These solders are our fathers, mothers, brothers, sisters, sons and daughters. Our Project American Heroes '57 Chevy is a way to honor and support them. All parts, talents, and time have been donated. Once the vehicle is auctioned, all monies raised will be donated to the Armed Forces Foundation, earmarked for Iraq and Afghanistan war vets. (You can donate at any time at

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No hot rod project is complete with out a ground-pounding engine, and this is where Project American Heroes pulls out the big guns. Ben Smeding and the crew at Smeding Performance took the task of building the heavy artillery 572 big-block. Smeding Performance (Rancho Cordova, California) is best known for its dyno tested, turnkey crate engines. When Ben agreed to custom-build our 572, we couldn't have been more pleased and promptly jumped on a plane to Northern California.

After all was said and done, zero hour arrived and it was time to dyno test the monstrous 572. After its break-in period, every attempt to make a power pull resulted in a bogged down motor and an eventual blowback/reversion through the carburetor. Ben thought that a valve was not properly sealing. Sure enough, after checking the valves it was found to be a sticky hydraulic roller lifter. Note: This is why Smeding dyno tests and tunes every engine after it's built. After a lifter swap and final tuning, the 572 was ready. And it did not disappoint. At 5,900 rpm it produced 717.8 horsepower, and at 4,300 rpm engine torque peaked at 709.5 ft-lb. The throttle response on the 572 is excellent. At 2,500 rpm the torque is a frame twisting 565.9 ft-lb and only climbs higher as the accelerator opens up.

Shock and awe? No doubt about it.

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Starting with a standard Dart block with an unfinished bore, Smeding Perfomance crew member Daniel Moody bores each cylinder to a gaping 4.630-inch and applies the finish hone, then paints it black. The Rottler M65 boring bar will automatically bore each hole to exact tolerances. The machine also has the capability to parallel deck the block or recess the bottoms of the cylinder bore for connecting rod clearance on long stroke applications.

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Smeding bores the block to within .005-inch of the finished bore. The block is then final-honed with an automatic Rottler honing machine with a diamond hone. Smeding matches each piston to its respective bore. This was an easy process with the high-quality Ross pistons because each piston was almost dead-on in size when compared to the next.

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When it came to balancing, every part of the assembly is weighed separately (rods, pistons, wrist pins, rings, and bearings) to determine the bob weight.

When it came to balancing, every part of the assembly is weighed separately (rods, pistons, wrist pins, rings, and bearings) to determine the bob weight.

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Smeding spends the extra time to internally balance all of their big-block Chevy assemblies. This makes it possible for the end user to easily adapt the correct flywheel and balancers.

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The crankshaft is a 4.250-inch stroke, 4340 forged steel unit that is nitrated and internally balanced. The lightening holes in the journal are drilled before the crank is heat-treated so that no part of the crank goes untouched. Smeing uses only 270 degree rod and main bearings for optimum lubrication.

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The 4340 forged H-beam connecting rods are 6.535-inch long, and incorporate ARP 7/16 cap bolts along with forged Ross Pistons with Total Seal moly rings.

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Racing Head Service (RHS) Pro Action #11002 aluminum cylinder heads come with 2.300-inch intake and 1.880-inch exhaust valves. Intake port volume is 360cc, exhaust ports, which are raised .500-inch, have a volume of 135cc. Smeding reshaped the combustion chambers, outwardly opening them up to take full advantage of the monster 4.630 cylinder bore. Once the grinding was done, the heads were milled .025-inch, bringing the chambers back down to a pump gas-friendly 9.9:1 compression ratio. The combustion chambers are now 118cc (just slightly lower then the advertised 119cc size from RHS). While the heads came pre-assembled, Smeding, like any engine builder worth his dyno numbers, completely disassembled the check spring heights and pressures. Smeding set the spring pressures on the Comp beehive springs to their preferred closed seat pressure of 125 pounds, and opened seat pressure (at .600-inch of lift) of 340 pounds.

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With all the machine work completed, the crank balanced, pistons and rods weighed and assembled...

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...the short-block assembly went together without a hitch. And we were nearly ready for the top end build.

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Smeding chose a Comp Cams hydraulic roller stick, ground to Smeding's specs of .613-inch lift (on both intake and exhaust), duration at .050-inch for intake of 248 degrees and 258 degrees for exhaust. Smeding orders its cams for a late-model engine, so they come with a stepped nose. This allows for the easy use of a thrust plate; no need to mess with thrust buttons to stop camshaft walk.

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Comp's extra-large, heavy duty adjustable single roller timing chain assembly was used.

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Smeding degreed the cam for 108 1/2 degrees intake lobe center, which equates to 1 1/2 degrees of advance for better low-end drivability.

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When we asked Ben why he uses Pro Race, ProStreet balancers, his reply was: "They are very affordable and work excellent." Smeding has never had one fail.

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A Canton oil pan (# 15-350) was used. These particular ans fit on '66-67 Chevelles and have a shorter sump to work with Tri-Five steering. The pan is clearanced internally for a large stroke crank and incorporates integral crank scrapers. A Melling standard volume oil pump with a Canton pickup tube was installed before the pan, obviously.

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Smeding chose to go with Comp's high body lifters, which are commonly used in high-performance applications. Smeding prefers this configuration because of the added lifter-to-tie-bar-to-block clearance and uses them in higher end applications where the extra cost is warranted. Compare the size of the lifters in the middle to a stock one on the left and an average sized aftermarket lifter on the right. Does size matter? Apparently so.

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Because of the thin spacing between cylinder bores on these big-bore engines, Fel Pro metal layer steel Permatorque MLS head gaskets were used. The use of this type of gasket is critical to the engine's sealing. The #1077 big bore gaskets are .041-inch thick, which combined with the piston-to-deck-height clearance of .003-inch, gives a relatively tight total of .044-inch, right where Smeding likes it.

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The pre-assembled RHS heads, which have all been gone through, are next up on the list.

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An Edelbrock Victor Jr. intake was used with some black RTV to seal the ends and ARP six-point stainless bolts. We also used a trick swivel stainless steel water outlet from Performance Stainless Steel. They so supplied us with a full compliment of stainless steel pipe plugs.

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Smeding recommended a Holley Ultra HP 950-cfm carb to feed our beast. This is the latest/greatest that Holley has to offer with anodized billet metering bodies and base plate, four-corner idle adjustment, and changeable idle feed restrictors.

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The Ultra series of carburetors are 100 percent wet flow tested from the factory and come with "out-of-the-box" performance calibrations. Even Ben Smeding Jr. helped out with some of the fastening of the ARP bolts.

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Believe it or not, the more time-consuming aspect of this engine build was installing the March serpentine system-2 1/2 hours later it all came together. We found the instructions a bit difficult to follow, but eventually we got everything properly aligned and bolted on.

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Because of the possibility of variances in the mounting positions of some of their components, the March system doesn't come with a belt. A quick measurement with blue masking tape determined the length. The harder part of this equation is finding a good auto parts store that has the proper length belt.

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Holley supplied us with its new Performance Mechanical billet pump. It's a great looking pump and is solidly built. We had to clearance the March idler bracket with a dremel tool in order for the pump to fit.

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MSD recommended one of its billet Ready-to-Run distributors. The folks there were more than confident that this would do the trick on our 572. We used the conversion kit that came with the distributor to lock out the vacuum advance. Chad Martin, our dyno guy, stayed with the blue advance stop bushing that is installed from the factory. This keeps the advance to a maximum of 21 degrees.

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He did change the advance springs to one heavy silver spring and one light silver spring. This will bring all the advance in by about 3200 rpm. To complete the ignition, we used an MSD #8202 Blaster Coil and 8.5mm Super Conductor wires.

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Here's the PAH heavy artillery after Chad fully dressed her in full "get-down-to-business" dyno garb. Smeding used Earl's black -8 Pro-Lite 350 hose and their Ano-Tuff hose ends and carb line kit. After breaking the engine in on standard racing oil, Smeding refilled it with Royal Purple 10-40 synthetic. Besides having a stealth look, this stuff is awesome to work with compared to braided stainless line. You can cut it with a razor knife and you don't have to battle any sharp frayed wires.

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Seeing is believing. We included a copy of the dyno sheet to look at. We also high lighted the peak torque and horsepower numbers to make it easier to read.


Comp Cams
Memphis, TN 38118
K&N Engineering
Riverside, CA 92507
Dart Machinery
Troy, MI 48084
Smeding Performance
Boerne, TX 78006
Ross Racing Pistons
El Segundo, CA 90245
Melling Engine Parts
Jackson, MI 49204
Canton Racing Products
North Branford, CT 06471
Sanderson Headers
King Engine Bearings
Cedar Grove, NJ 07009
Performance Stainless Steel
Scotts Valley, CA 95067
Racing Head Service (RHS)
Pro/Race Performance Products
Temecula, CA 92590
(800) 977-0767



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