Valve springs

[Robert Luland]

Why did Harley go to a 57A number on valve springs and can these be used on earlier ohv pans?

[bmh]

I believe the change to A was around the shovel head era. They can be used in motors back to 48 and possibly even 36. If you are talking a 48-52 pan and you intend on running the push rods with the hydraulic units on top they will take noticeably longer to pump up and quiet down, and could be noisy at hot idle. I would recommend the 18203-36 outer springs for that application. I would run solid push rods with the 57 or 57A springs in those motors, and would consider those items a mandatory upgrade if I was looking to run a cam that was more aggressive than stock on those motors. Anything with hydraulic tappets shouldn't be a problem.

[Robert Luland]

Thanks Brian. The purpose of the question was for a 48 with push rod hydrolics. Bob