If you read most enthusiast magazines, and especially the Chevy-only ones, you’d think that there isn’t a single person building a pre-’97 small-block Chevy anymore. With the advent of the LS series of engines, you might believe the hype that everyone has abandoned their old-style engine in favor of retrofitting the newer generation of powerplants. Camshaft makers have chucked those cores on the back lot along with flathead Ford and Buick nailhead components. Block makers have smashed those casts and Gen I small-block heads are little more than bulky doorstops.
We’re here to say that the demise of the original small-block Chevy engine is greatly exaggerated. In fact, COMP Cams sells more Gen I camshafts than LS by nearly a 2-to-1 margin. Go ahead and pop the hood on your favorite hot rod. Odds are, there’s a traditional small-block staring you in the face. If that’s the case, even if you need to replace the engine, you’ll be money ahead to put another Gen I in your car because of the cost of new headers, accessory drive, adapter bellhousing, and other miscellaneous stuff you’d need to pull off an LS engine swap. Those parts can easily set you back several thousands of dollars which you could be investing in power-making parts for your Gen I. Don’t get us wrong; we’ve done our share of LS engine buildups, and we’re not refuting the power potential of this design, the driveability, or any of the other positive characteristics. We’re just saying that there are a whole lot of people who aren’t ready to make all of the changes necessary to swap an LS engine in place of their old, trusty Gen I motor.
We’ve also more than once pondered the question of just how much streetable power you can squeeze from an early design small-block with all that we’ve learned in the past 20 years about cylinder head engineering, cam timing, and combustion chamber design. Could we find an LS competitor that looked like an anemic mid-’80s 305? And which LS would we set our sights on as a target? The carbureted GM Performance Parts LS3 makes 515 hp for about $7,500, but to build it beyond that you’re replacing the pistons and doing other work to beef up the bottom end. Before you know it, you’ve got an easy $10,000 in the engine. For that much money, you can buy a GMPP crate LS7, but then you have another host of engine swap challenges, and you’re still making “only” 505 hp.
As is the case with every engine build, the block is the foundation. A Dart Special High Performance (SHP) short-block starts with one of the company’s new cast-iron blocks. These incorporate all of the best traits of production small-blocks and add strength, the ability to handle a 4.125-inch bore, and a 3.750-inch stroke with steel rods. They also come with four-bolt, splayed main caps.
We decided that a 600hp Gen I motor would probably scare the crank right out of most LS engines. So when the engine in our Laguna gave up the ghost, it gave us the perfect opportunity to put our theories to the test.
The first step was to find the biggest small-block we could build without getting into exotic racing parts. It didn’t take long for us to identify the Dart Special High Performance (SHP) block as a worthy candidate. It can be built in displacements from 372 up to 427, and accepts all of the original small-block paraphernalia; it even has the ’55 Chevy front lower motor mount bosses. The ability to match the LS7 in displacement with a Gen I is very desirable, and helps even out the power playing field.
On the top end of the SHP block, the standard small-block Chevy lifter bores are retained, and mounting bosses for later-style roller tappet spiders are part of the casting. Starting with a new block removes all of the risk and guesswork of a used engine. The Dart SHP block even has blind head boltholes for zero chance of coolant seeping up the head bolts.
A little more research unearthed that Dart offers an SHP short-block with righteous parts that produces 550 hp and 545 lb-ft of torque on pump gas. Now we were definitely interested. Strength and durability issues are shelved with a 4340 forged steel crank, aftermarket steel rods, forged pistons, and splayed main block caps. Plus, Dart builds the blocks and heads that pro racers use to make 2,500 hp or more. Their SHP line is targeted at putting that same quality and performance expertise into the hands of street guys like us who also like to pound on our equipment at the racetrack.
We drummed up a conversation with Jack McInnis and Tony McAfee at Dart to see what it would take to shift that 550hp number north of 600 while still having an engine that would run on pump gas and be durable on the street. Those of you who follow our Laguna project know that we enjoy tossing the two-ton Betty into the corners on autocross and road race courses, but it spends more than its fair share of time in Los Angeles traffic. McInnis and McAfee thought that a bit more compression and camshaft will be sufficient to push the 427 SHP over the 600 mark without creating a hand grenade with the pin pulled.
One of Dart’s newest products is its assembly lube. The lube contains zinc, moly, and other high-pressure additives to protect your new parts during assembly and break-in. All of the friction surfaces of the bearings are coated with the lube prior to setting the crank in place.
There are definitely some things you should realize about an engine like this. That kind of horsepower and torque will plaster a smile on your face that will make your girlfriend jealous. But it’s not a docile, smooth idling, 25-mpg mill. It’s going to have a lumpy idle, low vacuum for accessories, and scare small children. We’ll have no problems tolerating it in bumper-to-bumper traffic in SoCal, but not everyone would. With that reality check out of the way, we stopped by Dart in Troy, Michigan, to photograph the drool-worthy parts that would make up the short-block of this potent anti LS engine.
Where the Money Went Description: Source: PN: Price: Dart 427 SHP short-block (assembled) Dart/Summit 3124272 $5,397.73 COMP Cams solid-roller camshaft custom grind COMP/Summit CCA-12-000-9 $324 COMP Cams billet double-roller timing set COMP/Summit CCA-7100 $95
