Cable,
I sold the 73121 for years at UltraDyne as the 920-921. Both springs are available from Pioneer, their manufacturer, who I bought directly from. I used the 73121 on the higher-lift UD BBC solid lifter cams. It had a little too much pressure for the lower-lift stuff, and requires the "Inner-Out" break-in method. I would not count on a clean break-in with inners installed on a 73121.
Lunati recommends the 73121 for all their BBC solids, I believe.
The 402A2 DOES NOT require the 73121s, and the 73124s are a better match.
Your Cranes work well, also. I'd ALWAYS remove the inner spring before break-in, on ANY solid or hydraulic cam, for safety's sake. Roller cams do not require break-in, so you can run full spring pressure from the git-go.
UDHarold
I sold the 73121 for years at UltraDyne as the 920-921. Both springs are available from Pioneer, their manufacturer, who I bought directly from. I used the 73121 on the higher-lift UD BBC solid lifter cams. It had a little too much pressure for the lower-lift stuff, and requires the "Inner-Out" break-in method. I would not count on a clean break-in with inners installed on a 73121.
Lunati recommends the 73121 for all their BBC solids, I believe.
The 402A2 DOES NOT require the 73121s, and the 73124s are a better match.
Your Cranes work well, also. I'd ALWAYS remove the inner spring before break-in, on ANY solid or hydraulic cam, for safety's sake. Roller cams do not require break-in, so you can run full spring pressure from the git-go.
UDHarold
