Chevrolet's crate engines have been used in racing now for several years. And while racers far and wide still debate the merits of crate racing (right along with the weather, politics, and the quality of the food at the local track), there's no doubt that crate motors are now a major part of the racing landscape.
One of the main benefits of crate engines--specifically Chevrolet "602" crate which is outfitted with iron cylinder heads and the more powerful "604" crate which has aluminum heads--is that they are quite affordable compared to most purpose-built racing engines. The iron-headed 602 engine (PN 1958602) is the least expensive at just under $4,000. For that you get a cast-iron block with four-bolt mains and a one-piece rear main seal. The crank is nodular cast-iron, the heads are Vortec with 64cc chambers. Powdered metal rods and cast-aluminum pistons provide a 9.1:1 compression. An oil pan with kickouts and large breathers on the left-side valvecover are the major concession to circle track racing. Altogether, the 602 engine is capable of 350 hp and 390 ft-lb of torque and a redline around 6,200 rpm thanks to lightweight springs and hydraulic lifters. It may be pretty pedestrian for a race engine, but it does work when everybody on the track is racing the same thing.
When more power is called for, there's Chevrolet's 604 crate engine (PN 88958604). It upgrades the package to Fast Burn aluminum heads, a forged steel crankshaft for improved strength, a high-rise single-plane aluminum intake, and 9.6:1 compression. It costs about a grand more, but for that you get 400 hp and 400 ft-lb of torque.
Either way, the crate motors are so limited in power, that any small difference between two of the same type can result in a real advantage on the racetrack. Both types of engines are sealed and while certified rebuilders are allowed to refresh the engines, when it comes to major repairs it's often a simpler matter so simply replace the entire engine.
As a result, there are plenty of crate engines available if you know where to look. As a way to recoup some of their costs, many crate racers sell their old engines to hot rodders or mechanics, but more as still gathering dust in the corners of race shops across the country.
We couldn't help but think that these castoffs have the right bones for a great engine build. Sure, the hydraulic roller lifters, cast pistons, and relatively low compression aren't great for racing, but both crate engines have components that can be used to make a quality hand-built race engine. So after a little--OK, a lot, actually--bench racing we decided to take a shot at seeing what could be built from a refuse crate engine. The sweet spot for reusing parts seems to be in the Street Stock classes, so we chose what we figured to be a typical rule book for a high-end Street Stock class. We'd find a used crate engine on the cheap, reuse what we can, and build a Street Stocker. The thinking is that by doing this, a racer can use the savings from his or her crate recycling program to invest in components that can actually help him gain an advantage on the competition. At least that's how the thinking went--we just had to do it to see if we were right.
1 During teardown, we weren't...
1 During teardown, we weren't able to punch out one of the internal oil gallery plugs at the back of the block, and KT Engines' Nathan Allmond showed us this trick. He uses a drill bit approximately the same diameter as the plug but doesn't drill through the plug. Instead, he allows the flutes of the bit to bite into the plug and then pulls it out from underneath.
2 Here, you can see the gallery...
2 Here, you can see the gallery plug stuck to the end of the bit.
3 Although we knew we wouldn't...
3 Although we knew we wouldn't be able to reuse the aluminum Fast Burn cylinder heads, we wanted a 604 crate engine because it comes with the stronger forged crank. Most Street Stock rules require a stock-style crank with a minimum weight of 48 pounds, and this one fits the bill perfectly. To keep the rotating weight down we're pairing the stock crank with a set of Carrillo's ultra-light A-beam connecting rods.
4 One issue with the Chevrolet...
4 One issue with the Chevrolet crate motors is that they use a weight on the flywheel to help balance the crank. We want the engine to be internally balanced, so even though the rod and piston combination we'll be using is quite a bit lighter than the stock stuff, the rear of the crank still required just over 80 grams to be added. The ideal solution would be to add heavy metal to the counterweights, but that's outside the price range of most real-world Street Stock builds. So we accomplished the same thing by welding up a couple lightening holes that had already been drilled into the rear counterweights from the factory. We intentionally added too much weight so that we could then go back and turn down the counterweights on a lathe to help clean up the crank a bit and reduce windage. Here, Allmond deburrs all the rough edges.
5 Whoever tore down the crate...
5 Whoever tore down the crate engine originally wasn't as careful as they should have been and left a few scratches on the rod journals. Here, you can see a mark left after a rod bolt has been smashed against the journal. It wasn't bad enough that the crank had to be cut down, but it is annoying.
6 Allmond worked hard to...
6 Allmond worked hard to buff out the scratches on the journal and did a good job of minimizing the damage to the point that we're no longer worried about tearing up the bearings. But extensive polishing can affect the journal diameter by a fraction of a thousandth of an inch, which can alter your bearing clearances.
7 The crates also use stock-style...
7 The crates also use stock-style press in oil gallery plugs in the front of the block. This can be a problem because the higher rpm levels of a built motor can create higher oil pressures in the main oil galleries. So Kevin Troutman threads the gallery holes with a tap in preparation for 1/4 pipe plugs.
8 Make sure not to tap the...
8 Make sure not to tap the center gallery too deeply because it has a crossover passage for the cam journal just inside the entrance. If the gallery plug is threaded too deep it can cut off oil to the journal and you will be left with a burned up bearing. A good rule of thumb is to tap the hole so that when fully inserted the end of the plug is flush with the block as you can see here.
9 Additionally, the crate...
9 Additionally, the crate is also outfitted with a single-row timing chain and cast-iron sprockets. We'll be changing them out for a much stronger and more accurate double-row timing set from Comp Cams, which requires a slight modification to the block. You will need to cut back the top edge of the boss for the oil gallery like you see here.