Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Spring Pocket Vs Spring Size vs valve lenth Help Needed
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Old 05-29-2012, 07:05 PM
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Quote:
Originally Posted by swompz
I measured the spring pocket on the bare alloy heads I've perquired & they look to measure 39mm= 1.550"

but im well confused as to what size springs & locator's I can use with them.
do I need to take spring retainer thickness into account when calculating valve lenth? ising an old valve it looks like a 4.911 valve lenth wouldbe right with an installed hight of 1.70"
im only looking to run a .450- .470 lift cam on the motor what options do i have???
Different retainers can give different installed heights (see diagram), but the thickness of the retainer doesn't enter into it- the measurement is taken from the underside of the retainer to the valve seat. If you use a spring seat locator, the measurement has to include it, up to the bottom of the retainer.

If you were going to run a high lift cam, a set of +0.100" valves would make sense. But if the lift is below 0.500", no need- just use stock length. BTW, your estimate of 4.911" is right at stock length.
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