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Buick 455 Camshaft Usage and Horsepower Ratings


By Dennis Manner, Senior Buick Engineer

In response to many questions concerning 455 engine camshafts and horsepower, there was only one factory produced Stage I camshaft used in 1969 400 and 1970-1974 455 Stage I Skylark GS Engines. This camshaft was identified by a single machined groove in the shank of the camshaft behind the front bearing journal.

The camshaft used in the 1971-72 Riviera GS and 73-74 Riviera GS Stage I engines was different than the Skylark GS Stage 1 cam and also different than the standard 455 engine cam. It provided more torque but a little less HP than the Skylark GS Stage 1 cam more appropriate for the heavier Riviera car. It can be identified by 3 machined grooves behind the front bearing journal.

The standard 455 engine as used in Skylark GS, Electra, Riviera, Wildcat or LeSabre models was the same engine (including camshaft) in any given model year. Four different camshafts were used in this engine in different years for non lead fuel/low compression engines in 1971 and later changes for fuel economy improvements as shown in the following chart.

Model 1970 1971 1972/3/4 1975/6
Year Standard Cam (Non-Stage 1) for the 455 in all series
Part# 1233232 1237665 1239629 1246739
Exh. Lift .458" .455" .449" .405"
Exh. Duration 332° 340° 331° 306°
Int. Lift .390" .390" .390" .390"
Int. Duration .293° .293° .293° .293°
Cam Spacing 117° 117° 118° 113°
Timing Advance * 124° 118° 123° 113°
* Centerline of Exhaust Cam Ahead of TDC

Model

All
Skylark GS Stage 1
1969 400/1970-74 455

All Riviera
1971-72 TS/1973-74
GS Stage 1
Part# 1383853 1384664
Exh. Lift .454" .457"
Exh. Duration 340° 322°
Int. Lift .407" .410"
Int. Duration 316° 297°
Cam Spacing 115° 118
Timing Advance* 118° 124°
* Centerline of Exhaust Cam Ahead of TDC

Regarding confusion over HP ratings, the standard 1970 455 engine was rated at 370 HP in Electra, Wildcat, Riviera nd LeSabre Models. To allow the Skylark Gran Sport the best opportunity for "Factoring in Competition" we rated the Stage 1 at 360 HP at 5000 RPM.

To be comparable in the Skylark GS we also listed the standard 455 at 350 HP (to be lower than the Stage 1) although the engine was the same as used in Electra, Wildcat, Riviera and LeSabre Models. Hopefully, this will clarify the confusion among the enthusiasts.

    Rocker Arm Ratio
  • 1967-68 400/430 - 1.59 to 1, aluminum
  • 1969-70, 400/455 - 1.54 to 1, stamped steel
  • 1971+, 455 - 1.6 to 1, stamped steel
*--- More information relating to "Stage I" and "Stage II" camshafts can be found on our "Buick Staging Chart" ---*



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