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valve spring question

473 views 2 replies 3 participants last post by  jeff swisher 
#1 ·
got a set of 1969 063 heads sitting here doing nothing. I was going to hail them to the shop and get them freshened up and have new springs installed. I was going to just go with the edlebrock sure seat? springs.
does the install height go by the springs, or by the cam?
looking at maybe a 1302 summit cam. jim
 
#2 ·
Jim,
I would not order springs until you have the shop measure the actual installed hgt of your particular heads. You need that to make sure the springs you get will work in your particular heads and with your chosen camshaft.
 
#3 ·
installed height tells you what the spring pressures are at a certain installed height on the head.
With retainer installed on the valve the distance from the bottom of the retainer to the spot where the spring will bottom out on the head is the installed height.

Sometimes that distance can be 1.7" or 2.0" if you install a spring rated at 100 psi at 1.8" installed height and stick it into more compression by installing it at 1.7" it will have more pressure.

How much more pressure depends on spring rate. say the spring rate is 300 then if you compress that spring .100" more than the 1.8 which will be 1.7 then you just added 30 psi more pressure so it will now be 130 psi installed at 1.7" height.

Shims/ locators or keepers can be ordered to correct some installed height issues.
 
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