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1968 Plymouth Valiant Specifications

The Dodge Dart is similar but has a longer wheelbase and length. These figures are from the AMA.

Note: Valiant 100 was coded VL, Signet was coded VH. Two door sedans were coded 21, four-doors 41. Together, they created codes such as VL21 and VH41.

1968 Plymouth Valiant Dimensionsdart/valiant sign

Track – front57.457.4
Track – rear55.655.6
Maximum overall car width71.071.0
Body width at No. 2 pillar69.669.6
Body “O” to front of dash.48.48
Overall car length188.4188.4
Overhang – front31.231.2
Overhang – rear49.249.2
Body upper structure length94.294.2
Body “O” line to CL of rear wheel94.294.2
Body “O” line o w/s cowl point10.810.8
Overall height53.754.0
Cowl height36.336.6
Deck height34.534.8
Rocker panel-front to ground7.57.8
Rocker panel-front from front wheel29.329.3
Rocker panel-rear to ground6.16.4
Rocker panel-rear from front wheel24.224.2

Ground clearance

Bumper to ground – front11.311.7
Bumper to ground – rear10.911.1
Angle of approach23.624.2
Angle of departure13.814.2
Ramp breakover angle12.012.6
Min. running clearance (specify)5.6 (Frame)5.9 (Frame)

Interior space

Front CompartmentAll
Effective head room38.4
Max. effective leg room at accelerator41.7
H point to Heel Point8.9
H point travel4.5
Shoulder Room55.4
Hip Room57.2
Rear Compartment
H point couple distance32.1
Effective Head Room37.3
Min. Effective leg room34.5
H point to heel point11.1
Min. Knee room2.1
Rear Compartment room25.8
Shoulder Room55.4
Hip Room57.2
Trunk: Usable luggage capacity14.5

1968 Plymouth Valiant and Powertrain (Dodge Dart was identical but had extra optional engines)

6-cyl Std axle ratio6-cyl Opt axle ratioV-8 Std axle ratioV-8 Opt axle ratio
Manual 3-speed3.23*, 3.55, 2.933.23*, 3.552.93*, 3.23*3.23*
Automatic2.76*, 3.23*, 3.55, 2.93*2.76*, 3.23*, 3.55, 2.93*2.93*, 3.23*2.76, 3.23*
Manual 4-speed - - 3.23*, 3.55**, 3.91*3.23*, 3.55**, 3.91**

Axle ratios marked with a single asterisk (*) were available in Sure-Grip; those marked with a double asterisk (**) were available only in Sure-Grip.

Engines170 six225 (opt)273318
CarburetorSingle barrelSingle barrelTwo barrelTwo barrel
Type, no. cyls., valve arr.Six, in-line, OHVSix, in-line, OHV90°, V-890°, V-8
Piston displacement, cu. in.170225273318
Bore spacing (CL to CL)3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5)
3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5)
# (front to rear) L. Bank--1-3-5-71-3-5-7
# (front to rear) R. Bank--2-4-6-82-4-6-8
Firing Order1-5-3-6-2-41-5-3-6-2-41-8-4-3-6-5-7-21-8-4-3-6-5-7-2
Compres. Ratio (nominal)
Cylinder SleevesNoneNoneNoneNone
Installation AngleLateral 0°, Up 3°Lateral 0°, Up 3°Lateral 0°, Up 3°Lateral 0°, Up 3°
Taxable Horsepower 27.727.742.248.9
Max. bhp* @ RPM[email protected][email protected][email protected][email protected]
Max. torque * (lb. ft.)[email protected][email protected][email protected][email protected]

* Max. bhp (brake horsepower) and max. torque corrected to 60°F and 29.92 in. Hg atmospheric pressure. All cars ran on regular (89) octane leaded fuel. The head and block were cast iron, without cylinder sleeves.


Pistons were aluminum alloy; they were a closed slipper-type, steel strut, ellipitcally-turned, and tin-plated.

Model170 (6-cyl)225 (6-cyl)273 (V-8)318 (V-8)
Weight (piston only ) oz.16.416.419.320.9
Clearance (limits) Top land.024 min..024 min..017 min..018 min.
Clearance (limits) Skirt Top.0005 - .0015.0005 - .0015.0005 - .0015.0005 - .0015
Clearance (limits) Skirt Bottom-.0005 - +.0005-.0005 - +.0005-.0005 - +.0005-.0005 - +.0005
Ring groove depth No. 1 and No. 2 ring.
Ring groove depth No. 3 ring.


From top to bottom, ring #1 and #2 were for compression, #3 was for oil. Compression rings were cast iron, lubrite-coated; all #2 rings had reverse twist and taper. Compression width was 0.078 and gap was 0.010 - 0.020. Oil ring width was 0.188.

Ring compression was twist and taper on slant six, twist and radius-faced on V8, tin-plated regardless, Rings were cast iron with steel expanders on the 170 alone; all others were a three-piece abutment-type setup with a stainless steel spacer-expander having chrome-plated segments.

Piston pins

All were made from carbon steel - carburizing grade.

Model170 (6-cyl)225 (6-cyl)273 (V-8)318 (V-8)
Type (Locked in rod, in piston, floating, etc.)Press-fit in rodPress-fit in rodFloatingFloating
Type (Bushing, in rod or piston)NoneNoneRodRod
Type (Bushing, material)--Bronze on steelBronze on steel
Clearance (In piston).00045 to .00075.00045 to .00075.0000 to .0005.0000 to .0005
Clearance (In rod).0007 to .00014 interference.0007 to .00014 interference.0001 to .0006.0001 to .0006
Direction & amount offset in pistonRight .06Right .06Right .06Right .06

Mopar engine connecting rods

Connecting rods were made of drop-forged steel.

Model170 (6-cyl)225 (6-cyl)273 (V-8)318 (V-8)
Weight (oz.)25.726.825.625.6
Length (center to center)5.7076.6996.1236.123
Bearing (material & type)Lead-based babbitt on steelLead-based babbitt on steelBi-metal gridBi-metal grid
Bearing (overall length).985.985.843.843
Bearing (clearance [limits]).0002 to .0022.0002 to .0022.0002 to .0022.0002 to .0022
Bearing (end play).006 - .012.006 - .012.006 - .014 (2 rods).006 - .014 (2 rods)

Crankshafts: slant six and LA V8

 Slant Six273 and 318 V8
MaterialDrop-forged steelCast ductile iron
Vibration Damper TypeNon-adhesive, rubber, dynamicNon-adhesive, rubber, dynamic
End thrust taken by bearing (No.)ThreeThree
Crankshaft end play.002 - .007.002 - .007
Main bearing (material & type)Lead-base babbitt on steel, removable, precisionLead-base babbitt on steel, removable, precision
Main bearing (clearance).0002 - .0022 specified,
.0005 - .0015 desired
.0002 - .0022 specified,
.0005 - .0015 desired
Main bearing (Journal dia. and bearing overall length) No. 12.75 x 1.0342.5 x 0.872
Main bearing (Journal dia. and bearing overall length) No. 22.75 x 1.0342.5 x 0.872
Main bearing (Journal dia. and bearing overall length) No. 32.75 x 1.2542.5 x 1.151
Main bearing (Journal dia. and bearing overall length) No. 42.75 x 1.0342.5 x 0.872
Main bearing (Journal dia. and bearing overall length) No. 5-2.5 x 1.562
Crankpin journal diameter2.1872.125

Dodge Dart and Plymouth Valiant Camshafts

ModelSlant Six273 and 318 V8
LocationRightCenter of “V”
MaterialHardenable cast iron, oil pump & distributor drive gear cast integrally
Bearings (Material)Lead-base babbitt on steelLead-base babbitt on steel
Bearings (Number)FourFive
Type of drive (gear or chain)ChainChain
Type of drive (crankshaft gear or sprocket material)Malleable cast iron or sintered iron (Super Oilite)
Type of drive (camshaft gear or sprocket material)Cast ironNylon-coated aluminum


ModelSlant Six273 and 318 V8
Valve Rotator, type (intake, exhaust)Low-friction lock on exhaustLow-friction lock on exhaust
Rocker ratio1.51.5
Operating tappet clearance (Intake).010 hotHydraulic
Operating tappet clearance (Exhaust).020 hotHydraulic
Timing (Intake – opens [°BTC])1010
Timing (Intake – closes [°ABC])5050
Timing (Intake – duration –deg.)240240
Timing (Exhaust – opens [°BBC])5058
Timing (Exhaust – closes [°ATC])610
Timing (Exhaust – duration –deg.)236248
Timing (Valve opening overlap)1620
Intake (Overall length)4.774.98
Intake (Actual overall head dia.)1.621.78
Intake (Angle of seat & face, deg)Seat: 44.5 – 45;
valve: 45 – 45.5
Seat: 44.5 – 45;
valve: 45 – 45.5
Intake (Seat insert material)NoneNone
Intake (Stem diameter).372 - .373.372 - .373
Intake (Stem to guide clearance).001 - .003.001 - .003
Intake (Lift [@zero lash]).394.372
Intake (Outer spring press. & length – valve closed, [email protected])62 @ 1.6592 @ 1.65
Intake (Outer spring press. & length – valve open, [email protected])154 @ 1.26185 @ 1.28
Intake (Inner spring press. & length – valve closed, [email protected])NoneNone
Intake (Inner spring press. & length – valve open, [email protected])NoneNone
Exhaust (Material)21 – 4N21 – 4N
Exhaust (Overall length)4.805.00
Exhaust (Actual overall head dia.)1.361.50
Exhaust (Angle of seat & face, deg)47 – 47.5Seat: 44.5 – 45; valve: 45 -45.5
Exhaust (Seat insert material)NoneNone
Exhaust (Stem diameter). 371 - .372. 371 - .372
Exhaust (Stem to guide clearance).002 - .004.002 - .004
Exhaust (lift [@zero lash]).390.400
Exhaust (Outer spring press. & length – valve closed, [email protected])62 @ 1.6592 @ 1.65
Exhaust (Outer spring press. & length – valve open, [email protected])154 @ 1.26192 @ 1.26
Exhaust (Inner spring press. & length – valve closed, [email protected])NoneNone
Exhaust (Inner spring press. & length – valve open, [email protected])NoneNone

Engine lubrication

Piston pins and cylinder walls were given a metered jet spray; pressure lubrication was used on main bearings, connecting rods, cam bearings, and, on V8s only, tappets (slant sixes had splash lubrication for tappets). Normal oil pressure was 45-65 psi at 2,000 rpm. The oil pressure sending unit was electrical; the oil intake was stationery, and the fuel filter was full-flow.

1968 Valiant Exhaust specifications

ModelSlant Six273 and 318 V8
Type (single, single w/cross-over, dual, other)SingleSingle w/cross-over
Muffler One, reverse flowOne, reverse flow
Exhaust pipe dia. – O.D., wall thick. (Branch)-1.75 x .075
Exhaust pipe dia. – O.D., wall thick. (Main)1.88 x .0752.00 x .075
Tail pipe dia. (O.D. & wall thickness)1.75 x .0431.88 x .043

Crankcase ventilation systems

All engines used induction-stype crankcase ventilation, with a cylinder-head cover outlet, controlled by a variable orifice; it took air in from the air cleaner (via a tube going to the oil filler cap) and discharged at the intake manifold, at or below the carburetor base. A check valve acted as a flame arrestor.

Every 6 months, owners were to inspect the crankcase ventilator valve, oil filler pipe cap, and associated hoses, clean the oil filler cap, and test the ventilator valve for proper operation; the crankcase ventilator valve was to be replaced every year.

Fuel systems and carburetors

All models used an 18 gallon (US) tank, with a filler outside the left rear fender; the fuel pump was mechanical, with pressure of 3.5 to 5 psi for slant six, and 5 to 7 psi for V8s. Both a fuel tank and fuel supply filters were used. Carburetors had separate automatic chokes, with heat control from the exhaust.

Idle speed – Manual*750650
Idle speed– Automatic*750650
Idle air-fuel mixture*14.0 – 14.414.0 – 14.4
Carburetors (Make)Ball and Ball**Holley
Carburetors (Model)BBS-4414 S (Manual),
BBS-4415 S (Automatic)
R-3919 A (Manual),
R-3920 A (Automatic)
No. used and typeSingle one-barrelSingle one-barrel
Barrel Size1.56 (Manual), 1.69 (Automatic)1.69

V8s 273318
Idle speed – Manual* 700650
Idle speed– Automatic* 650600
Idle air-fuel mixture* 14.0 – 14.414.0 – 14.4
Carburetors (Make) Ball and Ball**Ball and Ball**
Carburetors (Model) BBD-4416 S (Manual),
BBD-4417 S (Automatic)
BBD-4420 S (Manual),
BBD-4421 S (Automatic)
No. used and type Single two-barrelSingle two-barrel
Barrel Size 1.441.44

* Air conditioner off, transmission in neutral.

** Ball and Ball, a supplier to Chrysler from antiquity, was acquired by Carter, which renamed its carburetors “BBD.”


Six 170 Man170 Auto.225 Man225 Auto.
Timing (Degrees)5 ATC2.5 ATCTDCTDC
Timing (@RPM)700700650650


V8 273 Man273 Auto318 Man318 Auto
Timing (Degrees) 5 ATC2.5 ATC5 ATC2.5 ATC
Timing (@RPM) 700650650600


Spark advance

DistributorCentrifugal Advance (Crank ° @ RPM)
Part #StartIntermediateMaximum
28751990 @ 700-10000-7.4 @ 1000, 24.4-28 @ 198034-38 @ 4400
28752020 @ 700-10000-13.4 @ 1000, [email protected]28-32 @ 4400
28753340 @ 700-10000-14 @ 1000, [email protected]31-35 @ 3800
28753420 @ 650-9500-10 @ 950, [email protected]36-40 @ 4700
28753640 @ 700-10000-7.4 @ 1000, [email protected]25-29 @ 4000
28753660 @ 700-10000-7.4 @ 1000, [email protected]25-29 @ 4000


Distributor Vacuum Advance (Crank ° @ Inches of Mercury)
Part # StartIntermediateMaximum
2875199 0 @ 5-7.16-12 @ 8.512-17 @ 10
2875202 0 @ 5-7.16-12 @ 8.512-17 @ 10
2875334 0 @ 5-810-16 @ 1021-27 @ 13.5
2875342 0 @ 8.1-9.88-14 @ 12.216.5-21.5 @ 15
2875364 0 @ 6.2-9.74-10 @ 11.97.4-12.4 @ 13.8
2875366 0 @ 5-75-11 @ 87.4-12.5 @ 8.7

Manual transmission

All clutches were dry-plate, with oil pressure plate springs, and a facing of woven asbestos. Release bearings were permanently lubricated ball bearings. Torsion damping was done by coil springs with friction washers.

ClutchSlant Six273 and
slant six optional
318 3-speed318 4-speed
Make & TypeAuburnAuburnBorg & BeckBorg & Beck
Type Pressure plate springsCoilCoilCoilCoil
Total spring load (lb.) min.1330160019922345
Clutch Facing and Area
9.25 x 6.0

9.5 x 6.5

10.0 x 6.0

10.5 x 6.5
Clutch Facing Thickness.
Engagement cushioning methodTwo-piece cushionTwo-piece cushionFlat wave springsFlat wave springs


All models used torsion-bar suspension, adjustable via anchor bolt; brake dip and acceleration squat was controlled by inclined upper control arms and asymmetrical rear springs. Shock absorbers were direct-acting and made by Chrysler, with a 1-inch piston diameter. The front suspension was independent, with non-parallel control arms. Torsion bars were made of chromium alloy steel. A 0.88-inch diameter link-type front stabilizer was optional.

Front ball joints were to be lubricated every three years or 36,000 miles and inspected twice a year. Lubricant was P/N 2525035.

The rear suspension used parallel, longitudinal leaf springs, of a semi-elliptical, asymmetrical design, made of chromium alloy steel. They were 55 inches long and 2.5 inches wide in each case. The spring rate was 85 lb/square inch (105 at the wheel) on all but the 318, which used a 110 lb/square inch rate (132 at the wheel). Rubber mountings were used; Chrysler warned not to lubricate the rear springs, spring eye or shackle bushings, or shock absorber bushings.

Suspension details170 225273318
Front spring height by diameter 35.8 x 0.8335.8 x 0.8335.8 x 0.8535.8 x 0.87
Spring – Rate at wheel (lb. per in.)85859299
Number of leaves in rear springs454.56

Steering details

Manual steering was standard, power steering optional.

Wheel diameter 16.0
Turning diameter (ft.) – Outside Front (Wall to Wall)40.5
Turning diameter (ft.) – Outside Front (Curb to Curb)37.8
Turning diameter (ft.) – Inside Rear (Wall to Wall)21.9
Turning diameter (ft.) – Inside Rear (Curb to Curb)22.6
Outside whl. Angle with inside whl. at 20°18°
Steering spindle & joint typeBall joint
Steering typeRecirculating ball
Maker of steering systemChrysler
Manual steering gear ratiosStd: 24.0 to 1; Opt: 16.0 to 1
Manual overall steering gear ratiosStd: 28.7 to 1; Opt: 19.15 to 1
Manual number of wheel turnsStd: 5.3; Opt: 3.6
Power steering gear ratios15.7 to 1
Power steering overall gear ratios18.8 to 1
Power steering, number of wheel turns3.5
Steering linkageParallelogram with two equal length tie rods
Drag linkTransverse center link
Steering axis: inclination at camber7.5° @ 0°
Thrust bearingsOil impregnated sintered metal
BrakesDisc only for V8; drum or disk for slant six
Spindle inner bearing diameterDrum 1.0619; Disc 1.2494
Spindle outer bearing diameterDrum 0.6869; Disc 0.7494

Wheel alignment (range at curb weight and preferred)

Caster (deg.)Manual strg: -0.5°±0.5°; Power strg: +0.75°±0.5°
Camber (deg.)Left: +0.5°±0.25°, +0.5° preferred; Right: +0.25°±0.25°, 0.25° preferred
Toe-in (outside track inches)3/32” to 5/32”, 1/8” preferred

The sixes

 170 Slant Six 225 Slant Six
Gross Horsepower115 hp at 4400 rpm145 hp at 4000 rpm
Torque, lbs.-ft.155 at 2400 rpm215 at 2400 rpm
Compression ratio8.5 to 18.4 to 1
Carburetor type1-bbl.1-bbl.
Air cleaner typeSilencedSilenced

The economy eights

  273 V8318 V8
Gross Power 190 hp at 4400 rpm230 hp at 4400 rpm
Torque, lbs.-ft. 260 at 2000 rpm340 at 2400 rpm
Compression 9.0 to 19.2 to 1
Carburetor 2-bbl.2-bbl.
Air cleaner SilencedSilenced
Exhaust SingleSingle
Camshaft StandardStandard
Fuel RegularRegular

The hot eights

  340 V8
383 V8
Gross Power275 hp at 5000 rpm290 hp at 4400 rpm
Torque, lbs.-ft.340 at 3200 rpm390 at 2800 rpm
Compression 10.5 to 19.2 to 1
Carburetor 4-bbl.2-bbl.
Air cleaner UnsilencedSilenced


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