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Question about valve spring pressure for solid flat tappet cam

2K views 4 replies 4 participants last post by  gearhead18436572 
#1 ·
Comp cams 12-673-4 solid flat tappet
247 (I) @ .050
254(E) @ .050
.504(I) lift
.498 (E) lift
Lsa 112

Comp recommends valve spring #986-16
Installed height 1.75
Spring rate 322
Seat pressure 132

Or

987-16
Installed height 1.8
Spring rate 370
Seat pressure 139.5

Using 1.52 ratio rockers, I come up with 296 and 328 open spring pressures.

My engine builder suggested I use a spring with 354 open pressure and the tech from comp cams suggested a spring with 335 open pressure.

With no exotic light weight valves and valve train, what are your thoughts on open spring pressures?
 
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#3 ·
Ditto with RP. The manufacturer typically knows best. Some exceptions of course but that’s the safe bet.

Based on the mfg recommendations and your engine builder being in the same range, I would probably go with the slightly heavier spring.
As long as the spring isn’t excessive for the cam I would always go heavier.
 
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