[Steve C.]

Regarding the use of the engine prefix number.

Personally I've never seen anything used other than the number 51 for a traditional Pontiac engine.

Example, I've used two Comp Cams solid roller cams and both had part number 51-000-9

As noted the 54 is the engine prefix number for Pontiac.
The 000 indicates a custom grind.
The 9 indicates a steel billet roller core.

( another common core code used is -11 )

I have a copy of a Comp cam card with part number 51-000-10 and it stated 2.165 journals and a handwritten note indicating 55mm journal size. It was also a 4/7 firing order.

I've never used a hydraulic roller cam but I have seen cam cards for the early SD Performance Old Faithful cam with part number 51-000-9 and another two Old Faithful cams with part number 51-000-11.
Then two SD Performance revised stump puller hyd rollers, both with part number 51-000-11

All used the number 51


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