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Crate Motor - Repurposed CrateBuild your own race engine From the July, 2012 issue of Circle Track By Jeff Huneycutt Photography by Jeff Huneycutt
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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. The first step, obviously, was to find an appropriate donor motor. You might be able to get away with using the 602 engine's cast crank and powdered metal connecting rods if you are building a Pure Stock motor, but our plan had us aiming at the higher level Super Street class. This meant we wanted the forged crank from the 604. After a little searching we found a candidate that had been pulled from a race car and basically abandoned after a blown head gasket made it unfit for racing. We agreed to cough up a grand for the engine, which was probably a bit on the high side compared to what you will be able to get one for with a little haggling, but we considered it a way to help a racer get back on the track. The engine we purchased had already been torn down, so we don't have any photos of it together. But it did show signs of water having sat in a couple of the cylinders. We also noticed that a couple of the rod journals on the crank had been scratched by the rod bolts during disassembly--which is annoying but not a deal killer. Overall, the parts we wanted looked to be in decent shape and the rest will likely be finding its way onto ebay anyway, so we considered the project a go. The first step was to take the block and crank to be machined. We used KT Engine Development in Concord, North Carolina, which specializes in race engines. In this installment we'll take a look at a few of the components we'll be adding and our reasons why, machine up the block, fit the bearings and assemble the short block. So follow along! Eventually, we hope to put the completed recycled crate engine into a race car and put it to the test in real competition. We're shooting for a typical Super Street class, which is a high-end Street Stock racing usually on dirt. So we came up with the most common rules for this class. These fit no particular racetrack--so if your track has a Super Street-type class there will probably some differences in what you are allowed--we simply came up with what we have found is typical at most tracks. This means we may have to make a few changes when we do choose a specific track to race, but at least this allows us to make a real game plan. Block--Cast-iron, may over bore 0.060 Crank--48 pounds minimum weight, can't knife edge, stock stroke for engine size Pistons--Any flat-top, may float wristpins Rods--Any steel rod, must be stock length, may be bushed Heads--Stock or stock replacement, no Vortec, no porting, all bowl work must be in line with valve guide, screw-in studs allowed Valves--Must be steel, maximum size 2.020 intake 1.600 exhaust Rocker Arms--No shaft mount, may be steel or aluminum, roller tips allowed Camshaft--May run solid or hydraulic, flat tappet only, 0.500-inch max lift measured at the valve (0.025 lash allowed), lifters must be stock diameter for engine run Exhaust--Headers allowed, no Tri-Y collectors Carburetor--May run Chevy Quadrajet, Ford Motorcraft, or box stock Holley 650 (PN 4777), carb spacer maximum 1 inch Timing Chain--Chain only, no belts Oil System--Wet-sump only, any pan After a little searching we found a candidate that had been pulled from a race car and basically abandoned after a blown head gasket made it unfit for racing The connecting rod is very highly engineered and is fully machined, so even with the reduced mass, it should be capable of holding up to high rpm's and 500-plus horsepower in a racing environment  10 We won't bore you with...  10 We won't bore you with all the pictures, but KT Engines also went through the block and line honed the journals, bored the cylinders and honed them (with a deck plate) to a final size of 4.030 inches and decked the block to bring up the compression and ensure we won't have any more blown head gasket problems. Here, Kevin Troutman finishes up the block work by deburring the rough edges left by all that machine work.  11 Chevrolet supplies a quality...  11 Chevrolet supplies a quality 8-quart oil pan complete with a windage screen, kickouts and trap doors on it's crate engines, so we will be keeping it and the oil pump for this build.  12 Besides the fact that...  12 Besides the fact that most Street Stock classes won't allow a hydraulic roller cam anyway, the stock unit (top) only has a duration (at 0.050 lobe lift) of 208 for the intake and 221 for the exhaust. The Comp Cams solid flat tappet cam meanwhile specs out with 240 and 246 degrees of duration at 0.050 and is much more aggressive getting there. There is also another unique feature of this cam we are excited to try out. Notice how the lobes near the cam's journals beefed up with extra material. Comp now offers these special cores that are designed to significantly stiffen up the camshaft. By reducing cam flex it should help reduce the chances of wiping a lobe on these super agressive flat tappet designs as well as help control the valve opening and closing events more precisely for additional power.  13 Once the block is finally...  13 Once the block is finally ready, the task of fitting bearings is ready to begin. We're using King Engine Bearing's XP line of bearings which are designed specifically for the demands of circle track racing. King holds these bearings to extremely tight tolerances (the shells are matched to within 0.0001-inch) and can handle very high loading without flaking.  14 Powerhouse Products sells...  14 Powerhouse Products sells a very affordable set of micrometers and dial bore gauges that you can use to measure your own bearing clearances. Generally, you want 0.001 bearing clearance for every inch of journal diameter. So for a standard Chevy 2.100 rod journal, you are targeting a bearing clearance between 0.0020 and 0.0022. For complete instructions on how to measure and fit your bearings, go to www.circle track.com and search for  15 Stock cranks, like the...  15 Stock cranks, like the ones we are using, are notorious for often being slightly undersized. Plus, the extra polishing work we did on this one probably also contributed to the fact that we were getting too much clearance on both the main and rod journals. To bring the bearing clearances back into spec, we ordered up a set of X bearings from King. These bearings are thicker to take away 0.001-inch of clearance. For the main bearings we only needed to tighten up the clearance by 0.0005, so we used a standard shell in the housing bore and an X shell in the caps. The rods were running 0.003 total clearance, so we used both X shells to get an average 0.002 bearing clearance all the way across.  16 Once all the bearings...  16 Once all the bearings are properly fitted, they are coated with plenty of assembly lube and the crank is lowered into place.  17 Before installing the...  17 Before installing the main caps, lubricate the threads and underside of the head of each bolt with light motor oil.  18 One great feature of the...  18 One great feature of the crate blocks is the four-bolt main cap layout, which means these blocks should reliably be able to handle 500-plus horsepower. Here, Kevin Troutman torque the inner bolts on the caps to 70 lb-ft and the outers to 65.  19 After securing the main...  19 After securing the main caps, Troutman checks crankshaft endplay. Although this crank has already been run in this specific block, you can't take anything for granted. The new bearings mean endplay must be rechecked. We came out with 0.005-inch of movement fore and aft, which is well within tolerance.  20 Rules normally allow any...  20 Rules normally allow any piston as long as it has a flat-top. These units from JE Pistons are an excellent choice for this application. They have to work with a stock length 5.7-inch rod, so the compression height is relatively tall, but still, they are lightweight, designed to work with a low-friction 0.043 ring package and have a slipper skirt to further cut friction against the cylinder walls.  21 The JE pistons utilize...  21 The JE pistons utilize wire locks to hold the floating wristpins in place. Wire locks do an excellent job once they are in place, but they can be difficult to install and seem to have a tendency to spring out when they are about halfway in the hole and roll underneath your toolbox. I prefer to use a device called the Lock-In-Tool which makes installing wire locks a snap. It holds the wire lock in place so it can't spring out on your while you push it into the groove inside the piston's pin towers.  22 Old-school engine builders...  22 Old-school engine builders used to cut down their rod bearings on a lathe to reduce friction. King has already taken this step by making their performance rod bearings narrower to help reduce friction and the chances the edges of the bearings will rub against the crankshaft fillets.  23 This angle shows the most...  23 This angle shows the most unique feature of the Carrillo A-beam connecting rods. Unlike conventional I- or H-beam rods, the narrow beam (compare it to the big end of the rod to see just how much has been cut away) not only helps cut weight but also reduces windage because of the narrowed profile. The connecting rod is very highly engineered and is fully machined, so even with the reduced mass, it should be capable of holding up to high rpm’s and 500-plus horsepower in a racing environment.  24 For comparison's sake,...  24 For comparison's sake, check out the new rotating assembly on the left versus the unit that came out of the crate motor. We weighed the connecting rod, piston, rod bearing and rings, and the Carrillo/JE/King combination weighed in at 1,106 grams versus the stock weight of 1,373 grams. That's more than one-fifth cut off the total weight.  25 JE also spec'ed the best...  25 JE also spec'ed the best set of rings to work with the pistons. They recommended a set of 0.043/0.043/3.0 rings for the best combination of low drag and good oil control. The were installed to JE's specifications.  26 Once the pistons and rods...  26 Once the pistons and rods were together, Ken Troutman began the process of installing them in the block.  27 Carrillo goes the extra...  27 Carrillo goes the extra step and actually includes lubricant for the rod bolts. By knowing the exact properties of the lubricant you will be using, Carrillo can confidently provide the precise torque figure that will give you the correct amount of rod bolt stretch. If you have the capability of checking rod bolt stretch, it's always a good idea. But for those of you that don't have a bolt stretch gauge, this can provide some piece of mind that the rod bolts—one of the most stressed components in any race engine--are installed properly.  28 Ken Troutman checks the...  28 Ken Troutman checks the side clearance between the rods and the cheeks of the crank journals and determines that there is at least 0.020-inch of movement--more than enough to avoid excessive friction between the sides of the rods when the engine is running.  29 Here's a shot of the completed...  29 Here's a shot of the completed rotating assembly.  30 Up top, the pistons are...  30 Up top, the pistons are 0.005 in the hole at TDC to help maximize compression with the flat-top pistons.
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