by Richard Lasseter and Mark DeConti
as published in the Nov/Dec 1994 GS X-tra
The Stage 1 short block is identical to its non-Stage 1 counterpart. All 1970 and later Stage 1 heads were simply standard heads opened up to accept bigger Stage 1 valves. This is why standard and Stage 1 heads carry the same casting number. On the smaller bore 400 in 1969, the bigger valves woiuld've been shrouded too much to give any solid horsepower gain so the 1969 Stage 1 carried the standard size valves. Stiffer valve springs came with the Stage 1 option. You also got tubular pushrods which of course all 1970 and later 455s had biut in 1969 they were unique to the Stage 1. The 1970 Stage 1 carried a half point higher compression due to the larger valves taking up more space in the combustion chamber. Due to this fact, for any given year(except 1969) the Stage 1 had an actual compression .4 points higher than the standard 455.
All Stage 1 cars also had 5/8" i.d. oil pickup tubes. This was unique to the Stage 1 in 1969 and 1970 but about midyear 1971, all 455 engines came so equipped. Ditto for high pressure 60 psi oil pressure relief spring. Those minor, yet important, items were the only changes in the] Stage 1 oiling system. Internally, the only other change was the slightly hotter cam. It can be identified by one thin, non-functional groove on the barrel of the cam right before the first pair of lobes. Stage 2 cams have two grooves right together.
Enginewise, the only other changes were minor ignition and carb modifications. All Stage 1 cars were to be intially timed at 10 degrees BTDC. Jetting was one size larger than stockand secondary metering was also richer due to thinner secondary metering rods. All Stage 1 cars did come with HD cooling which primarily centered around a 7 blade fan and three core radiator. All ac equipped GS big blocks came with HD cooling.
Drivetrainwise, all Stage 1 engines came with a BB coded, six clutch pack transmission that also had a high rpm governor and increased pressure valving for neck-snapping, tire burning shifts. These transmissions had two capital B's on the trans. i.d. plate located on the passenger side of the trans. Finally, all Stage 1 cars came standard with a posi rear. In 1969 and 1970, the gear ratios were 3.42 and 3.64 for ac cars and non-ac versions, respectively. Other ratios up to 3.91 could be ordered. Starting in 1971 all Stage 1 cars had 3.42.
The serial number of 1969 and 1970 models were GS specific. The first five digits of the VIN designate the GS model. The hardtop was 44637 and the convertible carried 44667.
The GS350 was model 43437. The 455 Stage 1 was only available on the 44637 or 44667 models in 1969 and 1970.
In 1971, only one GS model was available in hardtop and convertible. The 455 and Stage 1 was now just an option to a GS 350.
This makes identification a bit more difficult but not impossible. The Stage 1 was only built in Flint MI. The seventh digit of the VIN must be an H for Flint assembly plant.
All Stage 1 cars came with chrome valve covers and bolts. The lower bolts have shanks for the spark plug wire holders. If the covers are chrome but the bolts are not something is not right. It is easy to chrome a set of valve covers but the bolts are a different story.
We hear somne 1969 GS Stage 1 cars came with chrome air cleaner lids but we know most of them didn't. The 1970 and later model GS cars had black painted lids. No GS ever had a fully chromed air cleaner.
The decals are all being reproduced so don't use them as a means of identification. Original Stage 1 decals had raised letters that are noticeable to the touch. There are also some pretty good repro's around.
The 1969-72 Stage 1 cars had two Stage 1 emblems. The 1969 emblem is on the hood and the 70-72 is on the front fender under the GS emblem.
Aftermarket and even GM supplies of these emblems are still available. It is worthwhile to take a closer look. The original 1970-2 emblems attached to the fenders at the S and 1. The emblems available today are the 1973-4 variety that attach at studs in the center of the emblem.
All Stage 1 455 cars used a different carb and distributor than its standard counterpart. The numbers are as follows:
Year Carb # Distributor # 1969 7029246 1111962 1970 7040246 1112016 1971 7041241 1112016 1972 7042242 1112016
The real nitty gritty of engine i.d. is the engine code. It is stamped on the block deck between number 5 and 7 spark plugs.
The key letter here is "S" The second letter of the code MUST be an "S" A 1969 would be RS, 1970 is SS, 1971 is TS and 1972 is WS.
The last three digits are the production code for the build date and is not used for Stage 1 idenitification.
The VIN is stamped on the block between number 1 and 3 spark plugs on 1969 and 1970 models. It is on the face of the driver's side of the block beneath the power steering pump on 1971-2 models.
If the last six digits of this number match the last six of the VIN then this engine originally came in the car. If not, the engine has been changed.
The trans also has a VIN stamped onto the case. Again if the last six digits match the dash VIN tag the trans is the original.
The driver's side axle tube has two letter code stamped on it. The 3.42 used code OO with 3.64 getting ON. These codes also designate posi. Some axle tubes may not have any stampings.
Beginning in 1971, the rear axle was increased to 8.5" ring gear. It visually became different from 1969 to 1970 design and carried different letter codes. The code for 3.42 was LWB or LW.
Just for the record, 12 bolt rears were not available in any Stage 1. Only Canadian built GS models came with 12-bolt rears.