Installed spring height

Theirs no realistic way to check this without atleast a dial indicator..
Now on the other thing you need and can make yourself..

You need a 1/2" conduit electrical pipe piece cut approx. .500.. Does not have to be exact,, but does need to be cut square and know exactly in thousandths what it measures.. The 1/2" conduit is very close to the id of the actual valve spring.

Remove your valve springs and any top retainers you might have.. Then reinstall the retailer with the piece of conduit on it like the spring sets. Put the dial indicator on top of the valve you are checking.. Set at ZERO.. Take a screw driver and start raising the valve while counting the measurements from the indicator.. Once it bottoms out you take that number you accumulated and write it down.. Then add the number the piece of conduit measures to the number from the lift test together.. That's your installed height.. (Make you a perniment tool.. Glue the conduit piece to a new valve retainer)

Usually comes out to approx. 1.020 - 1.060
The cams over the years have had different ramp speeds and that's where the installed height rating comes into play..
For instance these have been the faster lift rates >> Dyno 96-3 - 99-3 - 04-3 - 7x - 07-3
Slower rate cams Dyno 95-3 - 98-3 - all the 00 series cams..
All these cams are Non Symetrical and designed to float the valves,, thus making correct installed spring height critical..
 
Jerry, so what is the most desirable installed spring height and how does this affect the motor from one end of the spectrum to the other?
 
Thanks Jerry, that's similar to the method I'm using. Way back when dyno had a chart of spring wire diameter vs installed height to get the correct pressure with their springs. Any chance someone still has something similar?
 
Lets go to the end results and then back up..
The ideal situation the Intake Valve will just kiss the head,, leave a shiny mark,, not a groove or burr..
The exhaust should never touch the head..
You continuously work with the Intake valve till you achieve the the mark I mentioned.. This may take you a few weeks but well worth the efford..
This really needs to be done on the track or can be don't on the dyno.. Just remember not to over rev the engine,, if so it can give you a false reading..
Once the proper mark is achieved note the installed height it took to get you there..
Then with the installed height on the intake you add .010-.015 to the exhaust.. In essence we want the exhaust valve to have approx. 1 to 1 1/2 lbs less weight..

For us we found these numbers to be a good starting point on each class
Unrestricted > 21lbs In........ 20lbs ex
Gold plate >> same or 1 lb less on both
Blue Plate >> 17lb in........ 16lbs ex
Purple > 15 in .... 14 lbs ex.

Most all the time the spring rate will drop 1/2 to as much as 1lb within the first race... Then it should hold for basically the entire rebuild cycle..
The settings above is recommended for Dyno 96-3 ,, 99-3 ,, 7x ,, & 04-3
Usually when we set up a virgin block we go after 1.030 intake & 1.040 exhaust installed height for unrestricted and gold plate.. 1.040 in & 1.050 ex. for the purple and blue plate..
Spring combo's can vary and really only doing the testing I stated in the beginning of this post will get you right.. The good part of this once to achieve the correct setting you can duplicate it each time your rebuild that block,, only cutting the valve seats can change things.. Always install new valves and keep it simple..
 
CE1DC45B-B34C-498F-B668-575DEDBA29F3.jpeg

that attempt was just a fuzz to light on the exhaust side... lol ! 96-3 old master 7,100 ish
 
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