What is a 602 Crate Motor? | 602 Crate Engine Explained
What is a 602 Crate Motor?
Crate motors are a popular way to repower a muscle car or classic truck, but they are also a terrific way to bring parity to a spec racing series. The GM CT350 crate motor is a small block Chevy displacing 350 cubic inches assembled with a specific set of legal internal and external components, including GM’s efficient Vortec cylinder heads, which is sealed using special bolts and serialized tags to prevent modifications to the engine. This provides a level playing field in circle track racing or anywhere these “GM 602” crate engines can be utilized. The IMCA Hobby Stock engine rules are a good place to start for details on racing a 602 GM crate engine.
The tuned GM 602 crate engine is used primarily in dirt late models and modifieds. The sealed engine format means racers spend less time on the engine and more time behind the wheel, with engines only requiring oil changes and other light duty service parts, easily lasting an entire season. When it comes time for a rebuild the engines must be sent to a registered rebuild facility with the ability to reseal the engines with new bolts/tags upon completion of the rebuild. Speedway Motors is not only a source for new 602 crate engines but can rebuild and tune your GM 602 crate engine as well.
Why is it Called a 602 Crate Motor?
While the crate engine started life as GM’s CT350 (CT referring to circle track) crate engine, the 602 circle track engine is derived from the last three digits of the GM crate engine part number, which is 19434602. Introduced by Chevrolet Performance Parts to run in the Mid-East 602 Late Model racing class, the 602 became racer “short hand” for the IMCA Sealed GM 602 crate engine when discussing racing classes and the engine itself. This 602 late model engine name stuck and is now the preferred description for this crate engine vs the CT350 name it was given.
What Classes Use The 602 Race Engine
Why the 602 race engine then? It all came about due to the ever increasing costs of motorsports in general, but specifically dirt track racing. In the world of circle track racing, it is often those that have the biggest wallet and thus the best parts. To bring racing costs down and parity to the race cars (letting the driver and limited tuning be the real effort to get to the winner’s circle), dirt late model sanctioning bodies created racing classes with specific rules requiring a sealed crate engine to be used and Chevrolet Performance Parts introduced a series of sealed crate engines specifically for circle track racing in 2002.
The most common racing series you’ll find 602 crate engines running in are often the lower entry level classes, which include the IMCA Sport Mod and Hobby Stock classes. Regional series, such as the Mid-East 602 Late Models and Mid-East Modifieds, Fastrak Racing Series, Indiana Late Model Series (IMLS), Crate Racin’ USA (CRUSA), and others use these sealed crate engines as well to keep costs in check and provide a full field of exciting racing for fans from track to track in the series. Note: for many sanctioning bodies, crate engines directly from GM Performance may not yet be race legal. Several sanctioning bodies require additional seals and verification by authorized verification/build/repair facilities to be race legal. As always, consult your series or track rules to ensure compliance.
602 Crate vs Open Motor
What is an open motor and is it different than what is a 602 crate motor we’ve discussed above. The 602 crate motor is a brand-new small block Chevy V8 manufactured using all GM components and then sealed using special anti-tamper fasteners on key components. Whereas the open motor allows customization of components (such as using IMCA SBC cylinder heads versus the Vortec heads the sealed 602 uses) with varying performance outputs and generally higher costs associated with them.
Open motor class racing carries far less restrictions, which in turn, makes a level performance playing field that much more challenging than a crate motor class like those that use the 602 crate motor. Learn about Increasing Your Lead in Crate Motor Classes (Legally!) and be sure to shop our full line of Hobby Stock 350 Chevy small block V8 engine parts if you opt to go the open motor/claim route, but when comparing the 602 crate vs open motor rules and costs, it is easy to see the crate 602 benefits.
602 vs 604 Crate Motor
We are discussing the popular GM 602 crate motor here in this guide, but we’d certainly be remiss to not mention it’s sibling, the GM 604 crate motor that is used in some crate engine class racing as well. Like the GM 602, the 604 is a sealed crate engine built using all GM parts, though the 604 uses different cylinder heads and valvetrain to produce higher horsepower and torque. Our focus here is the popular 602 sealed crate engine, but if you’d like to know more about the 604 sealed crate engine you can read all about the 604, including full specs and supporting components in our GM 604 Crate Motor Guide elsewhere in the Toolbox.
602 Crate Engine in Street Car
We are often asked “Can I run a 602 on the street?” and the answer isn’t so cut and dried here. While the 602 crate engine block is simply a 350 horsepower small block Chevy, in many street applications you may find yourself having to swap components (such as the race-specific 8-quart oil pan) to allow proper fitment. Furthermore, the sealed aspect of the engine can make any modifications or upgrades to be more challenging, as you must cut away/destroy the bolt seals to tear down the engine or remove major components. Will the GM 602 sealed crate engine work for street use? Sure, but there are better crate engine alternatives out there for your street cruiser. At the end of the day, you have to remember just what is a 602 crate engine, and that it is a sealed racing engine for circle track use. As such, it is probably not the best use of your performance dollar to run a 602 crate engine in street car applications.
Chevy 602 Crate Engine Specs & Parts List
If you’re contemplating a 602 sealed crate engine racing class, we have provided not only the current 602 crate motor specs, including the GM 602 crate engine horsepower and torque, but a GM 602 crate engine parts list of supporting bits that you’ll need to get your GM 602 crate engine installed and running in your race car. Besides the parts listed below, our 602 accessory drive kit is a great option to consider as well with everything you need for your water pump and power steering drive systems.
- Horsepower: 350 hp @ 5,400 rpm
- Torque: 396 ft-lbs. torque at 3,800 rpm
- Displacement: 350 cubic inches
- Bore x Stroke: 4.00 inch x 3.48 inch
- Compression 9.1:1
- Block: Cast iron, four-bolt mains
- Cylinder Head: Cast Iron Vortec with 1.94”/1.50” intake/exhaust valves, 62cc chamber
- Crankshaft: Nodular iron, one-piece rear seal
- Connecting Rods: Powdered metal, with 3/8-inch rod bolts
- Pistons: Cast aluminum
- Intake: Dual plane high-rise aluminum
- Camshaft: Hydraulic flat tappet, .435”/.460” lift, 212°/222° duration @ .050-inch, 109°/116° centerline
- Rocker Arm Ratio: 1.5:1 - Stamped Steel
- Oil Pan: 8-quart, baffled pan with kick-out
- Recommended Oil: 15W50 Synthetic
- Fuel: 92 octane premium unleaded
- Maximum Engine Speed: 5,500 rpm
- Spark Timing: 34° BTDC @ 4,000 rpm
- Firing Order: 1-8-4-3-6-5-7-2
Carburetor:
A 650-cfm carburetor with a 4150-style mounting flange is the recommended carburetor to use on the 602 race engine. The carburetor jetting should start with #73 jets for both primary and secondary circuits. Some classes, such as Hobby Stocks, require a IMCA spec carb adapter for 602 crate engine use along with the class specific 500-cfm Rochester carburetor.
Air Cleaner:
A standard 14-inch diameter air cleaner with at least a 3-inch tall filter element is recommended for adequate airflow. A 4-inch element is preferred if there is enough clearance for one to be installed.
Flywheel:
The GM 602 crate engine uses a one-piece rear seal, so be sure that whatever external balance flywheel you order is machined for that.
Flexplate:
The same can be said for automatic flexplates. Only use a flexplate designed for one-piece rear main seal small block Chevy applications and with external balance.
Pilot Bearing:
The 602 sealed crate engine’s crankshaft is machined to accommodate the standard “small OD” roller pilot bearing originally used in the C5 Corvette, 4th Gen F-body, and GTO applications.
Starter:
We offer a variety of gear reduction starters for the small block Chevy that will work with both 153 and 168 tooth counts that are perfect for spinning over your Chevy 602 engine.
Fuel Pump:
To feed your 602’s four-barrel carburetor you’ll need a mechanical fuel pump capable of delivering at least 72 gallons per hour at 6-8 psi of fuel pressure. There are many options available at Speedway Motors.
Headers:
The GM 602 sealed crate engine has been tested to work best with a stepped header using 1-5/8-inch primaries stepped to 1-3/4-inch, with 32-36 inch long primary tube length.
Spark Plugs:
The 602 crate engine’s Vortec iron heads use a standard 14mm tapered seat spark plug with 3/4-reach. We offer several dedicated crate engine spark plug offerings for the 602.
Spark Plug Wires:
For the 602 we recommend a high-performance plug wire set with a minimum spark plug wire diameter of at least 8mm. On our fully dressed GM 602 crate engine we offer they are dressed using Moroso Ultra-40 spark plug wires.
Best 602 Crate Engine Carb
Knowing what cfm carb is best for a 602 will depend on several factors, including your racing class rules, track conditions, and more. For four-barrel carburetor classes, a 650-cfm carburetor works best according to GM’s 602 setup documentation. A 4150-style racing carb, such as these crate engine carburetors are a great option. Note for Hobby Stock the rules state a Rochester 2G 500-cfm carb must be used. We have additional carburetor information in our Toolbox article, Approved Upgrades for the GM 602 Crate Engine.
Best Fuel for GM 602 Crate Engine
Believe it or not, the best fuel grade for 602 crate engines is the easily available premium fuel octane found at your corner gas station. That’s right, GM recommends premium 91-93 octane fuel for the 602 race engine, mainly due to its friendly compression ratio, and is another effort to keep racing costs down without the need for expensive high octane racing fuels. Standard E10 pump gas is fine, however if you do find it easier for transport, IMCA does allow racing fuel (of similar octane) to be used. Note that E85 is not allowed, nor are performance additives, and like any sanctioning body, IMCA does inspect and test fuels of all race participants.
602 Engine Oiling System
The oiling system in the 602 is a wet sump system, again to keep costs down. The sealed crate engine ships with a steel 8-quart capacity oil pan designed for circle track racing. Per the rules, a one-inch inspection hole with plug is mounted to the pan. For open, or “claim” engines the same rules apply, however, you have your choice of Hobby Stock 350 Chevy small block V8 wet sump oil system components when building your claim engine.
602 Crate Motor Timing
As is the case with most racing sanctioning bodies, there is only so much you can do with your ignition timing. GM recommends total timing of 32 degrees at 4,000 rpm with a spark plug gap of .045-inch. The 602 includes an HEI distributor, while claim engines must source their own distributor. Per IMCA rules, you must also utilize a MSD rev-control unit. No other ignition system upgrades, such as a billet distributor or crank trigger system, may be utilized.
Best GM 602 Crate Engine Oil
As Mobil 1 is the official oil of Chevrolet Performance and as such the official GM 602 crate engine oil, the recommended oils to use in the CT350/602 crate engine is Mobil 1 Racing 0W-50 or Mobil 1 15W-50. That said, there are certainly considerations to be discussed with your engine rebuilder or tuner to use other viscosities and brands of motor oil with your 602.
602 Crate Motor Common Problems
The 602 sealed crate engine is built using all new components and spun on machinery to confirm oil pressure and proper sealing of gaskets. However, it is not actually run on a dyno or given any real break-in procedure. This means that breaking in your new 602 crate motor properly, following the Chevrolet Performance instructions, is critical to engine longevity. You will find many authorized 602 rebuilders/sellers offer a break-in package on an engine dyno or even fully dressed engines ready to race and we strongly suggest you take advantage of these packages to reduce any failures due to improper break-in and reduce the chance of having any 602 crate motor problems in your racing program.
602 Crate Engine Builders
Due to the sealed nature of the 602 crate engine program, you can’t haul your race engine off to your local builder for a refresh or any internal repairs if you have a failure. This prevents non-authorized builders or race teams from cracking open their crate motor for a little “something extra” for a race day advantage. The 602 sealed crate motor must be freshened up/serviced through authorized GM 602 crate engine builders, such as Speedway Motors. Our in-house circle track engine building facility can take care of your 602 rebuild, including using all the correct and legal GM internal components to 602 crate motor specs, and secure it with the proper sealing bolts/tags to keep track officials happy.
Additionally, we offer dyno break-in services, tuning services, and 602 crate engine packages that are fully dressed, dyno tested, and tuned that are ready to drop into your chassis. Learn more about our engine building services, dyno testing, and certified repair center offerings at Speedway Motors Racing Engines to help you get back behind the wheel of your race car and into the winner’s circle.
