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C4 Corvette - 1984 to 1996 - The 1985 Corvette

The 1984 Corvette was the first all new chassis since the iconic second generation cars of 1963. The new was of building Corvette created a lighter, smaller, and more capable automobile, a huge leap forward. One piece of the C4 that had missed the new and improved formula was the powerplant, the 205 horsepower RPO L83 350 cubic inch Cross Fire Injection V8. For the 1985 model year, that oversight was to be remidied.

1985 saw the introduction of one of them most popular engine / induction systems of all times, the L98 Tuned Port Injection 350 ci V8. Here was a genuine fuel injected engine. Unlike the Rocherter F.I. units of 1957 to 1965, the fuel made it to the engine via an electronic, not mechanical fuel injection system. As the manifold, plenum, runners, and throttle body was not only better performing than the CFI, it was also quite attractive.

The cast aluminum intake plenum sat high atop the engine, suspended by eight individual tuned intake runners that fed the cast aluminum intake manifold. The injectors chosen were supplied by Bosch, and they sprayed thier fuel into the intake ports, mixing with the air. The air entered the the dual bore throttle body by was of a new low restriction flat air cleaner that picked up cool, dense air from ahead of the radiator, out of the engine compartment. The new intake did away with the dects that ran on the underside of the hood to feed the side mounted intakes of the CFI's cast magnesium air cleaner assembly. The finmed Valve covers for the L98 5.7L engine continued to be made of cast magnesium.

New induction system improved the power output by 25 horsepower, but the big benefactor of TPI was torque. Engines in the 80's did not like to rev like their hi-performance counterparts of the early C3a. The TPI engines 225 horsepower maxed out at 4,000 rpm, down quite abit from its power equivalent, thwe 1979 L82 which peaked at 5,200 rpm. Torque on the other hand peaked a 330, arriving at 3,200 rpm. The 1979 L82 produced only 270 lb/ft, and that wasn't achieved until 3,600 rpm. Horsepower is what people buy, but torque is what they feel, and for 1985, that number was bumped up by 40 lb/ft over the 1984s CFI's numbers.

Delivering the power was accomplished much the same way as 1984, the same 700R4 4-speed automatic with overdrive or the 4+3 manual transmissions were offered. During the model yer, the overdrive switch for the 4+3 trsnsmission was moved from the center console to the shifter. With the increase in torque, the axle ratios were modified. The automatic has a 2.73:1 rear axle ratio as standard, however a 3.07:1 could be specified by ordering RPO G92. The 3.07 axle was included in with the optional Z51 Performance Handling Package. If a manual transmission was specified, the 3.07 axle was the only one available but the ring gear diameter was increased to 8.5 inches, an eighth of an in larger in diameter than the ring gear that backed up the 400-plus horsepower engines in the C3's since 1970. The driveshaft for base cars and the automatic received a steel 2.5 inch diameter unit, while all manuals and Z51 automatics were given a 3.o" diameter aluminum unit.

The interior became a bit more inviting in 1985 by offering the Custom Adjustable Sport Seats with leather coverings. The digital readouts for the instrument cluster was modified to for increased clarity. On the driver's sunvisor, an elastic strap was added for driver's to store maps, parking lot ticket, etc. In the storage wells, a "Service Parts Identifcation Label", commonly referred to as a SPID label, was added. The label listed all the RPOs the car was built with as well as spring codes, paint and trim codes, plus other non-orderable but included items. This item supplemented the "build sheet" that cars were normally shipped with, but usually discarded at the dealership level.

The wheels kept the same appearance as the 1984s, but in Z51 equipped cars, the wheels were a uniform 9 1/2 inches at all four corners. to enhance the appearance of the wheels, adhesive weights were applied to the inners surfaces, hidden by the wheel face. Now if the tires and wheels had to be rebalanced, evidence of the old wheel weight would not be seen.

In the quest for the best handling car, Corvette compromised ride comfort. For 1985, the spring rates on both the base and the Z51 cars was lowered. The base cars spring rates were 335 lb/in in the front and 233 lb/in in the rear. In 1984 those rates were 431 lb/in at the front and rear. For the Z51 cars, the 1985 numbers were 433 front and 330 rear; 1984 has a 634 lb/in spring rate in the front and a 525 lb/in rating in the rear. The stabilizer bars on base cars remained at 24mm in the front and 20 mm in the back. The front bar was 30mm in diameter in the front and the rear bar swelled to 24mm. This increased the anti roll tendency over the 1984 chassis which used stabilizer bar diameters of 25 and 20mm. The larger bars regained some of the handling prowess lost by having softer springs. To aid in car control, the Delco/Bilstein shock absorbers were included with the Z51 handling package or as a stand alone option as RPO FG3.

The color palate was revised slightly, mostly with changes to the two tone paint schemes. On the bodyside molding atop the fender gills at the hood opening, "TUNED PORT INJECTION" replaced the "CROSS FIRE INJECTION" tampos. The optional tinted removable roof option, RPO CC3 was altered to add a choice of tints, now available in blue (RPO 24S) or bronze (64S).

Total Production - 28,566
Model Number Description Production Base Price
1YY07 Corvette Sport Coupe 51,547 $21,800.00

Engine Codes
RPO Cu. In. Horsepower Torque Fuel System Trans Block Code Comp Ratio :1 Emissions Other
L98 350 230 @ 4000 330 @ 3200 Tuned Port Injection Man ZJB 9.0 All
L98 350 230 @ 4000 330 @ 3200 Tuned Port Injection Auto ZDF 9.0 All
L98 350 230 @ 4000 330 @ 3200 Tuned Port Injection Man ZJK 9.0 All Oil Cooler
L98 350 230 @ 4000 330 @ 3200 Tuned Port Injection Auto ZJJ 9.0 All Oil Cooler
L98 350 230 @ 4000 330 @ 3200 Tuned Port Injection ZJC 9.0 Export

Color & Trim Codes
Exterior Color Codes Interior Trim Codes
Color Code Color Cloth Base Seats Leather Base Seats Cloth Sports Seats Leather Sports Seats
Corvette Silver Metallic 13U Blue HDD2 / 28C ADD2 / 282 BDD8 / 28V ADD8 / 282
Corvette Medium fGray Metallic 18U Bronze HEE2 / 65C AEE2 / 652 BEE8 / 65V AEE8 / 652
Corvette Light Blue Metallic 20U Graphite HBB2 / 12C ABB2 / 122 BBB8 / 12V ABB8 / 122
Corvette Medium Blue Metallic 23U Gray HQQ2 / 15C AQQ2 / 152 BQQ8 / 15C AQQ8 / 152
Corvette White 40U Dark Red ARR2 / 742 ARR8 / 742
Black 41U Saddle HUU2 / 62C AUU2 / 652 BUU8 / 62V AUU8 / 652
Corvette Gold Metallic 53U
Corvette Light Bronze Metallic 63U
Corvette Dark Bronze Metallic 66U
Corvette Bright Red 81U
Light Corvette Blue Metallic /
Corvette Medium Blue Metallic
20U /
Corvette Light Bronze Metallic /
Corvette Dark Bronze Metallic
63U /
Corvette Silver Metallic /
Corvette Gray Metallic
13U /
Corvette Coupe
Overall Length 176.5
Height 46.7
Width 71.0
Wheel Base 96.2
Track F / R 59.6 / 60.4
Curb Weight 3224 Auto
3216 Man
Dimensions are in inches, weight in pounds unless otherwise noted.


1984 - A Brand New Corvette
1985 - Tuned Port Injection
1986 - The Roadster Returns
1987 - Sport Handling Arrives
1988 - Corvette Turns 35 and let the Corvette Challenge Begin!
1989 - Good-bye 4+3; Hello ZF 6-Speed
1990 - King of the Hill. Period.
1991 - A New Look
1992 - LT1 Returns
1993 - 40 Years of Corvette in Ruby Red
1994 - Brand New Inside
1995 - The King is Dead, Long Live the King!
1996 - End of an Era, Grand Sports and Collectors

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