SC rocker arms vs. early cars

[Tom F2]

I've heard that early cast rocker arms (69-77) are different from SC and later (78-89).

Can anyone clarify for me?

[gled49]

I believe the foot is a little longer, identified originally with a small casting “B” or a triangle.

[r lane]

Some time in the 60-70s, football teams came up with the tear away jersey. I think that philosophy applied somewhat to a change in the rocker arms as prior to the pressure fed tensioners, that items failure, which happened frequently, could be catastrophic with the valves being hammered into the pistons. A more fragile rocker arm was preferrable as the weak point.

[Tom F2]

Originally Posted by gled49

I believe the foot is a little longer, identified originally with a small casting “B” or a triangle.

Thank you, Gordon. So are they functionally the same? Or is the longer foot there to accommodate the longer duration of some camshafts?

[gled49]

They came along with the 49mm cam housings, formally 47mm. I suspect the cam lobe profile was bigger and they didn’t want the rocker to runoff the end of the foot, but I’m really not sure. You can run late rockers on early engines but not sure if u can run early rockers with 49mm cam housings.

[gled49]

Early and late rockers.

[Bira]

Originally Posted by gled49

I believe the foot is a little longer, identified originally with a small casting “B” or a triangle.

You’re absolutely spot on