What determines which degree lock you use.Is it the type of valves.duel spring or single with damper.Or a performance thing.Thanks for your knowledge.
Valve spring retainer determines type needed as far as angle. Valve determines style of keeper. So you could have, as an example, single groove 10 degree
it's a performance thing....if you run a big cam, you need a stiff spring, so you need a stronger retainer and keepers.
You can't just change the keepers, or locks. The retainer dictates which lock you use. A 7 degree retainer uses a 7 degree lock, a 10 degree retainer uses a 10 degree lock. They are a matched set.
The 10 degree are machined steel, very strong; the 7 degree are stamped out. Get the 10 degree, cost isn't an issue and you'll feel better about it.
Also, most cam manufacturers have specific recommendations for springs and other hardware to use with their various cams....they know what works.