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Firethorn Metailic 36

CVOA Competition Event Guidelines

                Approved by CVOA Directors and Executive Council July 27, 2001 Clarksville, IN. Update 2006



Many thanks are extended to the numerous members who contributed to the creation of this document. Special recognition is also given to Duke Williams for his insight, vast technical experience, and drive to improve the rules governing the CVOA Competition Event and creating the basic document and format from which this document developed. Also recognized for his input into developing the guidelines is John Cowall, who brought his many years of experience organizing and operating autocross events for the Michigan Sports Car Club.



The Cosworth Vega Owner's Association has traditionally organized an "autocross" timed competitive event in conjunction with the national meeting known as The Roundup. An auto cross is generally a serpentine circuit defined by traffic cones, or other discernable markings, laid out on a large paved area such as a parking lot. It is designed to test vehicle handling and driver skill. Course times are usually in the range of 30 to 120 seconds, and speeds usually do not exceed 60 miles per hour. Due to the logistics and cost of organizing an auto cross, Roundup organizers are encouraged to work with the SCCA or local auto cross clubs to secure a location, timing equipment, and event insurance. Each event will have an Event Chairman appointed by the Roundup Chairman with the advice and consent of the Executive Committee and Regional Directors.


The Event Chairman is vested with event management responsibility and authority. He/she may appoint technical, safety, course control, timing and scoring, and administration personnel as required. The Event Chairman shall treat all personnel with courtesy and respect, and as the ultimate arbiter of any disagreements or disputes, the Event Chairman's decisions are considered final.


Each competitor shall be allowed a minimum of three to a maximum of five runs, time, weather and track conditions permitting. A competitor may use any number of qualified vehicles in any Class( es); but shall receive only the total number of runs specified per competitor at the event. The competitor, may thus compete in more than one Class. Additional runs will be allowed after the conclusion of official timing as long as the course is available, but will not be counted towards the official timed results. These additional runs are designated as "fun runs".


The Event Chairman will maintain all entrance forms and tabulate the official results, to be turned over to the Roundup Chairman after the conclusion of the event, but prior to the event banquet. The Roundup Chairman shall retain annotated Entry Forms and any official timed results other data deemed relevant by the event chairman for a period of 6 months. An official results report shall be submitted to the Cosworth Vega Magazine editor at the conclusion of the Roundup for inclusion in the Cosworth Vega Magazine issue following the Roundup.



Entrant / Driver must be a registered CVOA member, director, officer, family member or friend who is registered for the Roundup or otherwise qualified by the Event Chairman. Driver must possess a valid, current driver's license issued by a recognized authority. Drivers are encouraged to enter Cosworth Vega powered vehicles, but other vehicles may be entered in a "non-Cosworth" Class.


Following the actual event, (Chairman, time and course availability permitting), drivers who are qualified for the event may take additional runs in any vehicle(s) which passes the safety inspection for the event. Such "fun-runs" should be timed but shall not be considered part of the event for competition purposes.


Drivers and passengers (if permitted) must wear a properly fitting D.O.T or Snell (85 or better) approved helmet and production or otherwise improved seat belt(s) and shoulder belt(s).


Insure proper Classification of competitors .

Inspect safety of vehicles to include, but not limited to; suitable safety belts, no loose objects inside vehicles, good brake operation, securely mounted drivers seat, securely mounted battery, no loose components in engine compartment or chassis, no cord or unsafe breaks showing on tires. Inspect helmet(s) for suitability.



Cosworth Vegas are to be classified in Stock, Modified, Competition, or Unlimited Classes. Eligibility for each Class is based upon meeting specific requirements with allowed modifications. (See following Articles and Appendix). A Cosworth Vega which exceeds the allowable Stock, Modified, or Competition Class modifications, is to move up to the next Class for which Class modification requirements are not exceeded. A non-Cosworth (or Open) Class shall be provided for non-Cosworth Vega powered vehicles.


A vehicle may compete in more than one Class should an entrant do one of the following;


A) Change specification during the event which would place it into a different Class (e.g. change tires).

B) Opt to complete in a Class above that Class for which it would normally be qualified.


Each entrant shall be assigned a number by the Event Chairman which he / she shall retain for the duration of the event and shall be displayed on both sides of the vehicle. In addition, the Class in which the car is being run shall be displayed in which the car is being run shall be displayed on each side of the vehicle. In addition, Class changes must be advised to the appointed scoring operator. Suitable numbers can be affixed to rear side windows on 8” x 11" size cardboard taped inside (or out) with bold magic marker numbering or via white shoe polish, or other methods.



The Event Chairman shall appoint a team of technical inspectors who are familiar with CVOA rules, mechanical operation, and components of vehicles.


Should a competitor wish to change components which would change its Classification during the event (such as tires, rims, ignition system, etc) a technical inspector must be notified to approve and inspect said modifications



Stock Class Cosworth Vegas must conform with "as built" OEM dimensions, specifications, weight, and equipment configuration with the exception of modifications that do not potentially improve performance including repair parts with the following clarifications and exceptions:


1. Tires must be DOT approved with a minimum UTQG tread wear rating of 140, and have evidence of a discernible tread pattern with no body cords visible via wear in tread area or cracks in sidewall area .

2. Road wheels must be 13" in diameter, no wider than 6", and maintain the 0.45" OEM offset. Offset can be verified by measuring the vehicle track for conformance with OEM specifications.

3. Any shock absorber (except air shocks) generally available to the public or through a CVOA program and designated by the manufacturer to be a suitable replacement for the HV77 body style is acceptable. "Double adjustment" shocks are not allowed.

4. Front wheel alignment may be set to any value available using OEM suspension bushings, camber / caster bolts, and tie-rod ends.


5. The engine and associated systems must meet OEM configuration.and specifications including valve seat geometry with the following allowable exceptions:


A maximum cylinder overbore of .030" is allowed

Initial ignition advance and centrifugal advance curve may be modified from stock. Vacuum advance, if

added, must be disconnected during competition.

A rev limiter may be added to the OEM HEI system

The EFI adjustments may be set anywhere within their available range. (Note: A richer mixture is not

advised as it may overheat the catalytic converter)

The PCV system may be modified to reduce oil ingestion, but must maintain a "closed" system.


6. Cosmetic modifications, OEM accessory front air dam, and or rear spoiler or similar after-market parts are allowed as long as the estimated on course speed will not exceed 60 mph for more than 10 percent of the estimated run time.

7. 1975 models may upgrade to the 76' rear brake configuration which must include the 1976 combination valve (part number 2620845).

8. A higher capacity radiator is allowed.

9. A non-production alternator drive is allowed, but the alternator must be functional and remain electrically connected to the vehicle electrical system.

10. The spare tire, jack, and lug wrench may be removed.

11. 1975 models may be updated with T-50 5-speed transmission and / or 4.10 rear differential.

12. The catalytic converter may be replaced with a modem-type converter.

13. Pulse-air system may be removed or disabled.

Any muffler suitable for street use may be installed.



Modified Class Cosworth Vegas must confirm with "as built" OEM dimensions, specifications, weight, and equipment configuration with the exception of modifications that do not potentially improve performance including repair parts. Any GM H-Body-based vehicle from 1971 through 1980 may compete in this Class if powered by a Cosworth Vega engine and meets other parameters of this Class. Stock Class cars may compete in Modified Class at the entrant's option. Clarifications and exceptions to this requirement are as stated in Article V with the addition of the following modifications and those in

Appendix 1.

1. Rims may be of a different offset than stock, with a maximum 13" x 6" diameter / width.

2. In addition, up to nine modifications from Appendix I will be allowed.





Any four-wheeled GM-H body vehicle, or its derivatives, powered by a Cosworth Vega engine, that is ineligibl for or modified beyond the limits or Stock and Modified Classes shall compete in Competition Class. Stock or Modified Class cars may compete in Competition Class at the option of the entrant.



Any four-wheel vehicle, powered by a Cosworth Vega engine, that is ineligible for or modified beyond the limits of Stock, Modified, or Competition Classes are eligible to compete in the Unlimited Class. Cars from previous classes may compete in Unlimited Class at the option of the entrant.



Any four-wheeled vehicle, other than one powered by a Cosworth Vega type engine, is eligible to compete in the Open Class. This is the "non-Cosworth" Class in which Cosworth Vega powered vehicles may not compete.



For each of the previous Classes there is a Women's Class available to female competitors only. Women havethe option to compete in other Classes for which their vehicle is qualified.



It is recommended that a First Place trophy be awarded for each Class with a minimum of three entrants. A Second place trophy should be awarded in each Class with at least five entrants. A Third place trophy should be awarded in each Class with at least six entrants. Trophy distribution is based on the Round-Up budget and the discretion of the Round-Up Chairman. Driver's name, Cosworth Vega dash number (if applicable), and best time should be published in the Cosworth Vega Magazine for the Stock, Modified, Competition, and Unlimited Classes. Non-Cosworth Vega vehicles should be identified by year/make/model or type of vehicle. Open Class results should-be published by driver name, vehicle year/make/model or type, and best time.




Modification to the steering system that alters the production ratio including the OEM accessory 16:1 steering gear assembly.

Non-production front and/ or rear anti-roll bars including non-production type front pillow block bushings and/ or sway bar link bushings.

Non-production type suspension bushings.

Non-production suspension springs.

Any substitution, deletion, or addition to production brake components.

More than .030 inch engine overbore. Up to 0.030" overbore is considered "normal engine overhaul" and not a modification.

Engine stroke greater than the production specified 3.16 inch.

Removing material from the cylinder head or valves other than the OEM equivalent (single angle) valve re-seat, or non-production inlet or exhaust valves.

Increased compression ratio greater than the production 8.5: 1.

Any non-production atmospheric induction system, modification, substitution, or addition to of any production EFI components. A suitable air cleaner system must be installed.

Any exhaust system which includes some type of muffler which exits behind the driver.

Modification to the HEI system (considered to include the distributor, coil, and high voltage wires) other than asspecified in Article V paragraphs 6(b) and 6(c); includes non-conforming high voltage wires.

Removal of the engine driven radiator fan.

Any non-Production transmission or differential components or ratios.




FRONT END ALIGNMENT SPECIFICATIONS for "periodic motor vehicle inspection" (1975 and 1976

Monza and Vega Service and Overhaul Manual Supplements, Specifications, Section :1)


CASTER: -2 3/4 degrees to +1 1/4degrees

CAMBER: -1 1/4degrees to +1 3/4 degrees

TOE: 7/16 toe-out to 5/16 toe-in

RIDE HEIGHT AND TIRE DATA (1975 and 1976 Monza and Vega Service and Overhaul Manual

Supplements, Specifications, Section 3; see note below for tire data sources)

TIRES BR70-13 or195/70R-13 185/70R-13 205/60R-13

FRONT RIDE HEIGHT 7.37" min 6.87" min 6.57" min

(Dim. "J", measured from ground to bottom surface of rocker panel 26 inches aft of front axle REAR RIDE HEIGHT 7.37" min 6.87" min 6.57" min.

(Dim. "K", measured from ground to bottom surface of rocker panel 16 inches forward of-rear axle centerline)

TIRE. STATIC LOADED RADIUS 11.0" 10.5" 10.2"


TYPICAL LOAD INDEX 88 (1235 1bs.) 85 (1135 lbs.) 86(1168lbs.)

(Minimum allowable is 84, 1102Ibs.) (BR70-13 max. load is 1150lbs. at 32 psi max. press.)

Note: The above tire data is derived from a range of data published by tire manufacturers. The Tire and Rim Association promulgates new, full tread depth tire dimension values and tolerance ranges for standard sizes, and some manufacturers specify a tolerance of plus or minus two percent for specified data. Actual static loaded radius may vary from quoted values based on actual vehicle load, inflation pressure, and tread wear. The above tire dimension data (and ride height data derived from static loaded radius values) should be considered a guideline. Ride height dimension checks must be accomplished with the vehicle on a level surface. If a vehicle deviates from these standards, inspectors should take into account tire manufacturing tolerance, actual load and inflation pressure, and tread wear before concluding that the suspension ride height has been modified.


FRONT TRACK = 54.3 inches

REAR TRACK = 53.1 inches

Note: The track dimensions are derived by subtracting 0.5 inches from the base vehicle track dimensions specified in the 1976 Vega Product Information Manual and 1976 sales brochure. Base Vega 13 x 5 inch wheels have an offset of 0.20 inches. Optional six-inch wide wheels, including the Cosworth Vega aluminum wheels have an offset of 0.45 inch which narrows the track by 0.5 inches. Chevrolet did not publish adjusted track dimension data for the 0.45 inch offset wheels. Front track should be measured by computing the average of the dimensions measured across the front and rear face of the tread to eliminate the effect of toe. Also, camber may affect the front track measurements.


170 PSIG (production camshafts and indexing)

(1975 Cosworth Vega Service and Overhaul Manual Supplement, page 6-21, Specifications, Engine Tune-Up)

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