Rebuilding Part 2 - Upgrading The Crate

In case your dog ate last month's issue of Circle Track, we'll fill you in. This is the second part in our engine build series where we are trying to create a competitive Super Street engine from a castoff Chevy crate motor.

Since Chevrolet's 602 and 604 crate engines have been popular for a few years now, that also means there are now more than a few worn out or downright blown-up engines lying around in race shops across the country. Since the idea of a sealed crate engine is that little to no work can be done on it--and because they are relatively inexpensive to begin with--most crates are simply replaced after a couple of seasons or whenever anything breaks. Many racers have tapped into the hot rodding market as an area for selling their used engines, but we've found there are still plenty tucked away underneath workbenches or in the forgotten corners of race shops.

In the last issue, we started the project by taking a look at what parts from the Chevy 604 we could reuse after it had been discarded because of a blown head gasket. After the race, engine specialists at KT Engine Development finished machining the block and balancing the crank, we fitted the bearings and installed the rotating assembly.

This time around we'll continue the assembly with a few tricks thrown in to help make this engine as competitive as possible on the racetrack.

Last month we finished up the improved short-block in our repurposed crate. The original four-bolt main block and forged crank remains, but the rotating assembly has been lightened considerably thanks to Carrillo A-beam rods and JE forged pistons.

Last month we finished up the improved short-block in our repurposed crate. The original f
1 The typical Super Street rule book mandates flat tappet lifters with a maximum cam lift of 0.500-inch. So we ditched the 604’s hydraulic roller and spent a lot of time consulting with Comp Cams to spec in the ultimate race cam option for this package. What we came up with is a solid flat tappet with 0.301/0.351 lobe lift for the intake and exhaust, 240/246 duration at 0.050 lift and 108 degrees of lobe separation. To hit the 0.500 maximum valve lift we’ll use 1.7 ratio rockers for the intake and 1.5 for the exhausts. And we’ll just squeak under the half-inch lift rule thanks to a 0.025 inch lash allowance that’s pretty common. And best of all, these lobes came right out of the catalog so they’ve already been put to the test for valvetrain stability.

1 The typical Super Street rule book mandates flat tappet lifters with a maximum cam lift
2 This cam is also unique in its design. Comp calls this the “Lobe Locker,” and as you can see it connects the lobes on either side of each journal to help provide extra rigidity. With aggressive cam lobes and strong valvesprings, it’s getting more and more difficult to keep flat tappet lifters from grinding off the nose of the cam lobes. Comp’s engineers say that any flex in the cam caused by the increased pressures placed on it can contribute to lobe damage, and the Lobe Locker design helps protect against precisely that.

2 This cam is also unique in its design. Comp calls this the “Lobe Locker,” and as you ca

3 Comp provides a packet of specially formulated assembly lube with all of its flat tappet cams, and we applied it liberally before installing the bump stick in the block.

3 Comp provides a packet of specially formulated assembly lube with all of its flat tappe
4 Chevrolet’s crate motors are based on the newer block design with a one-piece rear main seal. This block isn’t normally used for racing, so it requires a little thinking ahead. For example, this block uses a camshaft thrust plate which requires a cam with a smaller bolt pattern diameter for attaching the timing chain sprocket. All of the timing and valvetrain parts we ordered are the older style with the wider bolt pattern diameter, which means we can’t use the thrust plate.

4 Chevrolet’s crate motors are based on the newer block design with a one-piece rear main
5 Of course, the solution for this is simple. The thrust plate goes into the box of leftovers. Instead, we included an old-school camshaft thrust bearing while bolting up the timing chain sprocket to the end of the camshaft.

5 Of course, the solution for this is simple. The thrust plate goes into the box of lefto

6 Adding the thrust bearing means the original plastic front cover will no longer work. Of course, we were more than happy to replace it with a much more durable stamped steel front cover from Bradley Auto Parts.

6 Adding the thrust bearing means the original plastic front cover will no longer work. O
7 Here’s an area where we made a judgment call. The original 8-inch stock damper is still functional and could work just fine. But we doubt that’s the best way to be competitive, so we’re trying out Fluidampr’s new CT Gold damper. This unit weighs just 8.6 pounds versus the stock damper’s 14, and the weight that remains is much closer to the crankshaft centerline thanks to the Fluidampr’s 6.25-inch diameter.

7 Here’s an area where we made a judgment call. The original 8-inch stock damper is still
8 Before bolting up the cylinder heads, it’s always a good idea to check that the zero mark on your aftermarket damper actually matches up with top dead center for the number one cylinder.

8 Before bolting up the cylinder heads, it’s always a good idea to check that the zero ma

9 We wanted the 604 crate engine as a foundation for this project because of the forged steel crankshaft (the crank in the 602 engine is cast), but the aluminum cylinder heads aren’t legal in any Street Stock class. The original plan was to hunt up a pair of double-hump heads and machine them up. But those heads are as rare as the proverbial hen’s teeth and cost a fortune, so we went the more logical route and sourced a pair of stock replacement iron heads. The RHS iron Pro Torker heads are a great option. They are very cost effective, can be run right out of the box and have options available that put them close to a stock alignment. They arrived bare, and we paired them with a set of Manley Race Flo steel valves.

9 We wanted the 604 crate engine as a foundation for this project because of the forged s
10 When it comes to building race engines, value isn’t just what you pay for a part or component, but also what you have to spend to make it race ready. For example, the RHS heads came practically race ready right out of the box, including a competition-level valve job. Cylinder head specialist Kevin Troutman found he needed only to lap the valves to the seats before they were ready for installation.

10 When it comes to building race engines, value isn’t just what you pay for a part or co
11 We did, however, deck the heads to help bring up compression. Out of the box these Pro Torker heads have combustion chambers sized at 67 cc’s. After a few passes on the decking machine, Troutman was able to get the chambers to a more manageable 62 cc’s.

11 We did, however, deck the heads to help bring up compression. Out of the box these Pro

12 We’re also going a bit outside the norm for the valvesprings. To cut weight, engine builder Ken Troutman uses a set of Comp high-performance springs originally designed for LS engines. These springs (left) are smaller in diameter at 1.300-inch versus a standard sized spring for this application (right) at 1.550. The smaller diameter spring also means a smaller retainer, and significant weight savings are the result. The standard combination weighs in at 175 grams while our setup is just 117 grams per spring and retainer. Hopefully, it will mean a higher rpm redline on the racetrack.

12 We’re also going a bit outside the norm for the valvesprings. To cut weight, engine bu
13 At the springs’ set installed height of 1.835 inches the seat pressure will be 150 pounds. At 0.500 valve lift the open pressure will be 410 pounds.

13 At the springs’ set installed height of 1.835 inches the seat pressure will be 150 pou
14 The narrower springs require a little machine work to cut down the diameter of the valve guides.

14 The narrower springs require a little machine work to cut down the diameter of the val

15 The RHS heads have pushrod holes sized approximately the same as a stock head. For an aggressive cam with larger 3/8-inch pushrods the pushrod holes must be enlarged. It can be done by hand but Ken Troutman prefers to cut the heads for clearance on a milling machine because it is faster and more precise.

15 The RHS heads have pushrod holes sized approximately the same as a stock head. For an
16 Here’s a sample of the engine result.
17 The original oil pump will be reused, but you should never trust an oil pump if—like your momma always said—you don’t know where it’s been. Since this engine had mechanical problems in its past life, we completely disassembled, cleaned and checked the pump for any signs of damage or debris.

17 The original oil pump will be reused, but you should never trust an oil pump if—like y

18 If you are building your own engine, you may not have the tools to prime the oil system before starting the engine for the first time. Applying a little extreme pressure lube or assembly grease between the geroter lobes will help the pump prime more quickly and get motor oil flowing through the engine faster.

18 If you are building your own engine, you may not have the tools to prime the oil syste
19 One-piece rear main seals are unusual with built Chevy race engines, but they are standard equipment on crate motors. The easiest way to install the seal is to place it on a flat surface and tap the seal retainer down around it.

19 One-piece rear main seals are unusual with built Chevy race engines, but they are stan
20 If you aren’t familiar with this configuration, don’t forget to install the gasket between the seal retainer and the block.

20 If you aren’t familiar with this configuration, don’t forget to install the gasket bet

21 Slide the adaptor over the end of the crank making sure the lip of the seal doesn’t get twisted. This retainer means an oil pan made for this design must be used. We’re reusing the crate oil pan because it is a good design that comes complete with a windage tray.

21 Slide the adaptor over the end of the crank making sure the lip of the seal doesn’t ge
22 As mentioned previously, this engine was originally cast aside because of a blown head gasket that allowed coolant to get into one of the combustion chambers. Thanks to a set of Cometic high-tech multi-layer-steel (MLS) head gaskets, that won’t be a worry this time around. The MLS gaskets do an excellent job of sealing off combustion even if we wind up pushing the engine too hard and it suffers a bit of detonation.

22 As mentioned previously, this engine was originally cast aside because of a blown head
23 We’re also upgrading the fasteners to high-quality ARP head bolts to help the head gaskets do their job. The ARP bolts are highly engineered fasteners. For example, transition to the underside of the head of the bolt isn’t a sharp corner but is rounded for added strength. To go with that, the washers have a chamfered edge on one side. This edge should always face against the underside of the head of the bolt to provide proper clearance. ARP also provides a special lubricant to apply to both sides of the washers to keep the surfaces of the bolt and the head from galling together and throw off your torque readings.

23 We’re also upgrading the fasteners to high-quality ARP head bolts to help the head gas

24 In Chevrolet small block engines, the head bolt holes in the block are cut into the cooling jackets. To keep the coolant from seeping past the threads and contaminating the oil, thread sealant must be applied to all the bolts.

24 In Chevrolet small block engines, the head bolt holes in the block are cut into the co
25 Troutman bolts the heads to the block in three even steps, finishing by pulling all the head bolts to 70 ft-lb.

25 Troutman bolts the heads to the block in three even steps, finishing by pulling all th
26 If you haven’t already noticed, the key to our Super Street engine will be the valvetrain. To go with the lightweight springs and aggressive cam, Comp’s Ultra Pro Magnum steel rockers provide the optimum mix of light weight and rigidity. They are full roller to minimize friction and have channels to provide cooling oil to both the roller tip and the valvespring.

26 If you haven’t already noticed, the key to our Super Street engine will be the valvetr

27 If you remember, we’re using 1.5 ratio rockers for the exhaust valves (left) and 1.7 ratio for the intakes (right). The ratio is adjusted by the position of the pushrod tip to the rocker’s fulcrum. Notice how much more closely the pushrod cup is positioned inboard on the 1.7 ratio rocker.

27 If you remember, we’re using 1.5 ratio rockers for the exhaust valves (left) and 1.7 r
28 Here’s the point where we ran into another hiccup: To minimize flex, we will be using 3/8-inch diameter pushrods rather than the more standard 5/16-inch diameter. The Comp guideplates are sized for the larger pushrods, but when testing for correct pushrod length we noticed that before the valve reached max lift the pushrod was hitting the inside of the guideplate. We’ll have to grind the plates to provide a little more clearance, but in the meantime we used some 5/16 pushrods of varying lengths to find the correct size and ordered up a correct set of 3/8 pushrods. We’ll get the valvetrain buttoned up next month. Stay tuned!

28 Here’s the point where we ran into another hiccup: To minimize flex, we will be using

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Rebuilding Part 2 - Upgrading The Crate

Part 2 of Circle Track's series of rebuilding a ruined crate engine to go Super Street racing.