1968 Dodge Charger

[Paul Ceasrine]

December 1967

High Performance Car Magazine

Taking a looking at the 'new' 1968 Charger 383 (4-Speed) compared to last year's 1967 Charger 383 (4-Speed).

Article; 'Did We Miss Something At The '1967' Dodge Rebellion, And Did We Now Catch '1968' Dodge Fever.

Part 1

'1967' 383/325 HP 4-Barrel
325 Horsepower @ 4800 RPM
425 Foot Pounds of Torque @ 2800 RPM
10.00 to 1 Compression Ratio
Performance.................15.92 @ 86.7 MPH

'1968' 383/330 HP 4-Barrel
330 Horsepower @ 5000 RPM
425 Foot Pounds of Torque @ 3200 RPM
10.00 to 1 Compression Ratio
Performance.................15.15 @ 92.1 MPH

We asked, where did the nearly (-.77) quicker times come from, despite only a (+5) Horsepower increase in engine output.
Is the 1968 383/330 HP engine underrated, or is the 1967 383/325 HP grossly overrated. Or, is Chrysler completely
'off-the-charts' in listing the Advertised Horsepower rating of the 383 4-Barrel at '330' in the 'new' 1968 Dodge Charger 383.

Both cars have the near identical shipping weight - (1967 Charger '383' #3650 lbs.) and the (1968 Charger '383' #3653 lbs.)

High Performance Car will take a look at the major differnences;

For 1968, the 383 Engine has a different rotating assembly, though the bore and stroke sizes are identical.
The 1968 engine has a Piston positive deck height of (+.014), while the older 383 has a (-.007) below deck
Piston height.

The 1968 Cylinder Heads (Casting #2843906) are Open-Chamber style, with a 79.5 CC combustion chamber volume,
while the older 383 uses the (Casting #2406516) Closed-Chamber style with a smaller 73.5 CC combustion chamber
volume.

The difference in Cylinder Head and Piston Deck makes no change in either 383 Compression Ratio of 10.00 to 1.

Chrysler has stated that the 'Open-Chamber' design will improve cylinder volume flow, and that the new #2843906
casting will increase CFM flow, due to improvements in the port design.
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Both Cylinder Heads utilize the 2.08" 'big-valve' Intake, but the 'new' 1968 Cylinder Heads have 10% larger Intake Ports,
which now have a radius-type design instead of the older 'flat-floor' intake port shape.

The new 383 Cylinder Head now utilizes a 1.74" Exhaust Valve, while the 1967 and earlier 383 Cylinder Heads carry
a 'small-valve' 1.60" Exhaust.

The bigger exhaust valve, larger throat area opening, and improvements in the exhaust port design (less restrictive bends)
increases exhaust flow by 18%.
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Both the 1967 383 and 1968 383 utilize the same Valve-Train. The Camshaft unit has a lift of .425 Intake and .437 Exhaust,
with a Duration of 256* Intake and 260* Exhaust, and with an Overlap of 32*

Valve Springs remain the same, with a load rating of #134 lbs. with the Valve Closed, and #208 lbs. with the Valve Open.
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A big difference was found in the cast iron Dual-Plane Intake Manifold. The 1967 unit (Casting #2205968) which has been a major
complaint with 383 performance-minded drivers, has been replaced with a new larger runner and improved flow cast iron
Dual-Plane intake (Casting #2806301).

The 1968 Intake Manifold has 10% 'greater' Branch sizes, and a 50% increase in Runner-sizes.

Also, the carburetor mounting bore sizes have been increased from the 1 7/16" (Primary) and 1 9/16" (Secondary) on the
1967 Intake Manifold, to an equal 1 11/16" (Square-Bore size) on the 'new' 1968 Intake Manifold.

The incease in 'branch and runner' sizes, and larger sized throttle bore openings will provide for a significant improvement
in performance at the higher RPM levels.