Veteran
Posts: 143
 
Location: Denver, Colorado, USA | Hi Retired55. I'm not following what you mean by "opening up the spring perches to fit the newer styles available." Do you mean machining the spring pads on the cylinder heads to fit taller or larger-diameter springs? Or are you talking about using offset keepers and/or retainers to fit a taller spring? I've not heard "spring perches" used regarding valvetrain, so I appreciate the clarification to get a better idea of what you're asking.
At any rate, the first place to start with spring selection is what the camshaft profile and engine rpm require since the seat pressure and open pressure are dictated by the camshaft lift, ramp profile, and the maximum rpm the engine will see (valve weight also plays a role, but I'm assuming you're running factory sized steel valves from your comment about bone stock). The installed height is dictated by the retainer in relationship to the spring pad with the valves closed. If you already know with absolute certainty the cam profile (as in you have the cam card, have pulled the number, have personally measured, or had someone personally measure) and are struggling with which spring to use, you need to look at all the quality springs available with the suitable OD/ID (for the pad, retainer, and to clear the valve stem seal) along with install and bind heights to find one that gives you the seat and open pressures the cam and engine rpm need that falls within bind tolerance. Without more details (cam profile, your intentions for modification, etc.), any recommendation will be a guess in the last place you want guesswork. |
1955 Dodge 270 Hemi valve springs.
