Products to Compare (max of 3)
X
Compare These Parts
America's Oldest Speed Shop ® Talk to the Experts. Call 800.979.0122, 7am-10pm, everyday.
Help Center
Help Center

U.S.Order Line:

800.979.0122

(CST) 7am - 10pm

Race and Rod Tech Support

Mon-Fri 8am - 5pm

Canadian Order Line:

855.313.9180

International Order Line:

1.402.323.3200
Since 1952
Menu
Shop By
Support
Account

Legal Upgrades for the GM Crate 602/604

By Dave
8 months 18 days ago

All right, you’ve got your new 602 or 604 crate motor sitting there ready for race season. You’ve heard all the guys talk about what their motor is putting out, now it’s time to get that out of yours. So, it’s time to crack that puppy open, right? Wrong. Per the regs, you can’t alter the original assembly unless approved. So here are a few tips and tricks to help massage a few extra ponies out of that beast, without getting disqualified for the season.

Perhaps the easiest and simplest is swapping out the spark plugs. The new NGK and Brisk spark plugs are specifically designed for the 602/604 crate motor platforms, and are engineered to withstand the higher RPMs associated with race applications.

Next up is running the right carburetor. Making the right choice when it comes to carbs could mean the difference between having a winning car, and not. Using the formula found here we can do some calculations to figure out a rough estimate. Most 604 motors will go into “valve float” around 6800 RPM. So for the sake of argument, you could use 6200 RPM as a max. Willys Carbs has an option specifically designed for the 604. Based on a 750 CFM body, it is capable of flowing up to 900 CFM.

Believe it or not, your oil is also a major factor in pulling as much power out of your motor as possible. Products like the Lucas High Performance line of motor oils were designed to not only run cooler (up to 40°F cooler), but have also has been proven to stave off fuel dilution longer than other oils.

One more thing to keep in mind; word amongst the racers is that the OEM timing mark may vary from motor to motor. It is a good idea to locate your TDC (Top Dead Center) independently and mark it. Once you have marked it, it also might not hurt to add a timing tape like the one shown for finer control.

Last but not least, don’t forget about all the accessories you have at your disposal. KRC Serpentine Drive kits can help reduce pulley drag substantially, freeing up valuable horsepower. Don’t just focus on the engine of your racer either. Low drag Teflon bearings in the rearend will make your car roll easier, and limiting or eliminating brake drag will also help.

Products Featured in this Article

Related Articles

by Dave - Posted in Tech
8 months 14 days ago
We all want the most bang for our buck. Here are some upgrade options to help you safely pull the most power out of your new crate motor.
Learn More
by John - Posted in Tech Tips
6 months 8 days ago
In this Tech Tip, John gets to answer a favorite question of ours, what engine should I get?
Learn More
by Jeff K. - Posted in Tech
4 months 13 days ago
Follow along as Product Guru Jeff K. works his magic on a rather depsondent looking Chevy engine, bringing it back to its former glory.
Learn More
by Jason - Posted in Tech
8 months 14 days ago
Picking a proper camshaft for your project can rapidly deteriorate into chaos. So many possibilities. Want a little advice? Click here!
Learn More
by Jason - Posted in Tech
8 months 18 days ago
The art of selecting a camshaft that performs right in your street rod may become easier with experience, but the choice is less of a guessing game once you have a few of the basics, found in this latest article from Speedway.
Learn More
by Jason - Posted in Tech
8 months 19 days ago
There are a lot of options out there when you're ready for a replacement performance crate engine. But if you compare the competition to BluePrint Engines, you'll find the value is hard to beat.
Learn More
5 days ago
Speedway Motors and Classic Trucks called on GM Performance to power their ground up rebuild of a 1952 Chevy truck that was built in celebration of Speedway Motors’ 65th anniversary.
Learn More
by John - Posted in Tech Tips
6 months 7 days ago
In this Tech Tip, John answers a customer question about what would be needed to swap some additional power in place of his anemic 233c.i. Ford.
Learn More
by John - Posted in Tech Tips
6 months 7 days ago
In this Tech Tip, John discusses LT1 rotating assembly options for a customer looking to build a solid autoX, drag, and occasional strip powerplant for his Firebird.
Learn More
by Steve - Posted in Tech
4 months 12 days ago
A quick review of the Performance Tool W41036 Deluxe Engine Leveler available at Speedway Motors.
Learn More
Suggestions