If I subtract your lowest spring height of 1.854" from an in-spec height of 2.130" I get .276" difference, and that's shorter. Is the spring coil binding when the valve is fully open? If so, it'll destroy the cam...maybe pull the intake and have a look. If there is coil bind,the cam and lifters will need inspecting as well.
Terry ( I hope this isn't the case!)
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"It don't take but country smarts to solve the problem" (Smokey Yunick)
'41 Merc Town Sedan / 260" 8CM engine
'66 Fairlane four door / "warmed up"
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