USRA
Technical Bulletin: USRA B-Mod Engines
The USRA B-Mod division has grown dramatically in
popularity in recent years. The requirement for a
stamped rocker arm in our standard engine package has
been discussed thoroughly and has had its share of
controversy. The reason this rule exists is to limit the
valve train of this engine.
The rule book is a
set of limitations for what the racer is permitted to do
with the race car, including the engine with has
limitations cubic inches, compression, rod type, crank
type, head numbers, intake numbers and more. The valve
train has very few limitations other than the rocker
arm.
A stamped rocker arm will withstand only so
much stress before it fails and the racer has to build a
valve train within that tolerance. What is happening
more frequently is that racers are willing to exceed
that limitation to gain a performance advantage with the
risk of a part failure, which is usually the rocker arm.
One of the areas they are exceeding that limitation
is the valve spring pressure. Low quality rocker arms
and the flat tappet cam quality declining has added to
this dilemma. We have noticed these parts are failing
from excessively aggressive valve trains being too much
stress on the rocker arms, and from simply poor quality.
Because of these issues we feel that we need to
implement a valve spring rule. This will reduce the need
to stress parts for performance and lessen the potential
of these parts from failing due to poor quality. Since
we will now have a controlled spring rule then we can
remove the limitation of the required stamped rocker arm
and allow a full roller rocker arm with the standard
engine.
Effective January 1, 2023, if you choose
to utilize a full roller rocker arm then you will have
to adhere to the new valve spring rule, or you can stay
with the current stamped rocker arm rule and the current
spring rule will be permitted. However, the new spring
rule will be enforced with all standard engines
beginning in 2024.
See Rules 13.7.12 and 13.8.12
for amendments to these rules. You can download rules
for all USRA classes at usraracing.com/rules.
Continuing to crush it: Year after
year, the USRA continues to attract more racetracks and
dirt track racers through fair, logical and
cost-effective rules accompanied by an organization that
puts the racers, racetracks and their fans first. During
the 2022 Summit USRA Weekly Racing Series, more than 50
of America’s finest dirt ovals hosted over 1,000 nights
of racing.
To learn more, check out
usraracing.com for
schedules,
points,
photos,
souvenirs,
videos and more. Follow our social media channels on
Facebook,
Instagram,
Twitter and
YouTube.
Click here to get USRA news delivered to your inbox.
= = = = = = = = = = =
USRA OFFICIAL
SPONSORS: American
Racer Racing Tires, Beyea
Headers, Chevrolet
Performance, Christie
Door Company, Fast
Shafts, FK
Rod Ends, K1
RaceGear by Ryan Bowers, KS
Engineering, KSE
Racing Products, Mesilla
Valley Transportation, MSD, Nitroquest
Media, PEM
Racing Gears & Drivetrain, RacinDirt, Summit
Racing Equipment, Sunoco
Race Fuels.
USRA PARTICIPATING
SPONSORS: ARMI
Contractors, Boubin
Tire & Automotive, Brodix
Cylinder Heads, DAY
Motorsports, Innovative
AutoGlass & Window Tint, PBM
Performance Products, Star
1 Roofing & Construction, Stealth
Oilwell Services, Texas
Locomotive Solutions, TNT
Auto Parts, YouDirt.com.
USRA CONTINGENCY SPONSORS: AFCO
Racing Products, Allstar
Performance, Bryke
Racing, BSB
Manufacturing, Champ
Pans, Edelbrock, Hooker
Harness, Integra
Racing Shocks & Springs, JE
Pistons, Keyser
Manufacturing, Landrum
Performance Springs, Medieval
Chassis, Performance
Bodies & Parts, QA1, RacerWebsite.com, Real
Racing Wheels, Swift
Springs, Sybesma
Graphics, Wehrs
Machine & Racing Products, Wilwood
Disc Brakes Five1seven
Designs, Four
Seven Designs Salon & Boutique, Hi-Tek
Paving, Jerovetz
Motorsports Racing Parts, Penske
Racing Shocks, Race
Smart Wraps, S&S
Fishing & Rental, Traeger
Wood Pellet Grills by Elliott Motorsports.
USRA RACETRACKS:
67 Speedway of Texarkana,
81 Speedway,
Alien Motor Speedway,
Ark-La-Tex Speedway,
Arrowhead Speedway,
Big O Speedway,
Boothill Speedway,
Callaway Raceway,
Caney Valley Speedway,
Cedar Lake Speedway,
Chateau Speedway,
Crawford County Speedway,
Cresco Speedway,
Dallas County Speedway,
Deer Creek Speedway,
Diamond Park Speedway,
Eagle Valley Speedway,
Elk City Motorsports Park,
Fairmont Raceway,
Fayette County Speedway,
Gondik Law Speedway,
Hamilton County Speedway,
Humboldt Speedway,
I-35 Speedway,
I-90 Speedway,
Lakeside Speedway,
Lawton Speedway,
Longdale Speedway,
Lucas Oil Speedway,
Mason City Motor Speedway,
Midway Speedway,
Mississippi Thunder Speedway,
Pike County Speedway,
Rapid Speedway,
Rocket Raceway Park,
Sabine Speedway,
Sports Park Raceway,
Springfield Raceway,
Super Bee Speedway,
Superbowl Speedway,
Thunder Valley Speedway,
Tomahawk Speedway,
Tri-State Speedway,
Tulsa Speedway,
Vado Speedway Park,
West Texas Raceway,
Winneshiek Raceway.
##br>
Contact Info:
Jeff Nun
Chief Communications Officer
United States Racing Association (USRA)
1715 W 2nd St, PO Box 905
Webster City, IA 50595
|