The 1968 Harvey-Bailey L89 Corvette - By The Numbers

Alan Colvin Jul 1, 2005 0 Comment(s)
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General InformationYear: 1968Make: ChevroletSeries: 94Model: CorvetteEngine: 427ciHorsepower: 435Transmission: Four-Speed MuncieEngine Code suffix: IU

BlockCasting No. 3916321 or No. 3935439Main: Four-bolt

Cylinder HeadCasting No. 3919842* (aluminum)Intake/Exhaust Valve Size: 2.19/1.72Combustion Chamber: 106.8*While all 1968 L89 Corvettes used this cylinder head from the factory, the car now uses the No. 3946074 open-chamber head.

Intake Manifold (Aluminum)Casting No. 3919850 or No. 3919852 or No. 3937797Carb Type: 3x2-bbl Holley

CarburetorHolley 2300 Series 2-bbl, GM No. 3902353 (front or rear)Holley 2300C Series 2-bbl, GM No. 3925517EV (center)

Exhaust ManifoldsCasting (Lefthand) No. 3880827 Casting (Righthand) No. 3880828

DistributorStamping No. 1111296Engine/HP: 427/435hpHousing: Cast-iron external adjustmentPoint: Mag PulseNotes: Tach drive, vacuum advance

Alternator1100696, 42-amp, all with TI

TransmissionFour-Speed Close-Ratio Muncie M21Maincase: AluminumExtension Housing: AluminumType: Synchromesh, all forward gearsGear Ratios:First: 2.20:1 Second: 1.64:1 Third: 1.28:1 Fourth: Direct Reverse: 2.26:1Maincase Casting No. 3925660Extension Housing Casting No. 3857584Sidecover Casting No. 3884685Special Information: Carryover from 1967 except for maincase casting number change.

1968 Rear Axles All '68 Corvette rear axles are stamped with an alphanumeric identification code. The seven-digit code contains the axle-code prefix, the month and day build code, an axle-plant letter suffix code and, on Posi-traction axles, a letter code stamped below the axle code to provide source information.

On the '68 Corvette IRS rear suspension, the differential code is stamped on the bottom of the differential-carrier housing just forward of the rearend cover. The axle code reads from left to right. The two-letter prefix designates the gear ratio and any other specific information about the axle. The calendar month is designated by a two-number code from January (01) through December (12).

Plant Codes* G = Detroit Gear & Axle* B = Buffalo NY* K = McKinnon Industries (unverified)* W = Warren, MI

Posi-traction Codes* D = Dana Posi-traction differential* E = Eaton Posi-traction differential* W = Warner Posi-traction differentialExample: AL-04 09 W

E* AL = Axle Prefix: 3.08:1, Corvette standard Posi-traction axle* 04 = Month: April* 09 = Day: 9th day* W = Assembly Plant: Warren* E = Posi-traction Source: Eaton

*The Harvey-Bailey L89 Corvette used this rear-axle ratio.

From Corvette By The Numbers by Alan Colvin, published in 2002, used with permission of Robert Bentley Publishers.

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