Explain "Determining and setting spring height" to me....
09-19-2002, 03:26 PM
#1
Explain "Determining and setting spring height" to me.... How do you set it (I assume with shims, correct)? How do you determine what the correct height is, by the cam specs, spring specs, etc? I have included all relevant specs below, if they apply:
HEADS: TEA STG 2 5.7 2.02 1.55 Milled .005
CAM: TR 230/224 .569 .563
SPRINGS: Comp 987s "Final installed height of these springs will vary depending on cylinder head setup"
PUSHRODS: TR 7.4 Chromoly pushrods
Lifters: Stock GM
What is the variance they (Comp) speaks about, what does it depend on, and how do you determine the proper installed height? Thanks, Shawn
HEADS: TEA STG 2 5.7 2.02 1.55 Milled .005
CAM: TR 230/224 .569 .563
SPRINGS: Comp 987s "Final installed height of these springs will vary depending on cylinder head setup"
PUSHRODS: TR 7.4 Chromoly pushrods
Lifters: Stock GM
What is the variance they (Comp) speaks about, what does it depend on, and how do you determine the proper installed height? Thanks, Shawn
09-19-2002, 03:38 PM
#2
Re: Explain "Determining and setting spring height" to me.... You basically measure the distance from the spring seat to the retainer with the valve, retainer, and locks installed on the head.
You need to know the point at which you hit coil bind on the spring and the valve lift of the cam w/ your chosen rocker ratio.
Ideally you'd like to keep .1" of "room" between the coil bind point and you maximum lift. But alot go by .08"
You measure the distance with a spring height micrometer.
You need to know the point at which you hit coil bind on the spring and the valve lift of the cam w/ your chosen rocker ratio.
Ideally you'd like to keep .1" of "room" between the coil bind point and you maximum lift. But alot go by .08"
You measure the distance with a spring height micrometer.
09-19-2002, 05:49 PM
#3
Banned
iTrader: (54)
Join Date: Nov 2001
Location: Grants Pass, OR
Posts: 1,816
Likes: 0
Received 0 Likes
on
0 Posts
Re: Explain "Determining and setting spring height" to me.... Installed height depends upon a number of things including length of the valves, depth of the valve job, amount cut from the spring pocket, and the valve retainers themselves. Stock installed height is 1.800" for the LS1 and unless you change the former, it'll stay the same. The comp retainers maintain the 1.800" installed height and I believe the REV retainers are near 1.750" installed height.
So if your spring binds at 1.150" and your installed height is 1.800", then you have .650" of available lift. Subtract .050-.080 for coil bind, and you could lift these springs safely .570" to .600".
You setup your installed height based on what your cam dictates as far as lift, and what spring pressure you need to control the cam. And in some cases retainer to valve guide clearance. If you setup a spring higher, then you'll decrease seat pressure and vice versa. If you have springs capable of .650" of lift and you only plan to lift them .600", you can shim the springs to increase seat pressure. If you want to go the other way, you can cut the spring pockets or raise your installed height which will increase how much you can lift the springs before coil bind while reducing your seat pressure.
So if your spring binds at 1.150" and your installed height is 1.800", then you have .650" of available lift. Subtract .050-.080 for coil bind, and you could lift these springs safely .570" to .600".
You setup your installed height based on what your cam dictates as far as lift, and what spring pressure you need to control the cam. And in some cases retainer to valve guide clearance. If you setup a spring higher, then you'll decrease seat pressure and vice versa. If you have springs capable of .650" of lift and you only plan to lift them .600", you can shim the springs to increase seat pressure. If you want to go the other way, you can cut the spring pockets or raise your installed height which will increase how much you can lift the springs before coil bind while reducing your seat pressure.
09-19-2002, 07:48 PM
#4
TECH Fanatic
Re: Explain "Determining and setting spring height" to me.... Your cam supplier should tell you what spring load should be with the valve on the seat (if he knows what springs, valves, rockers, etc. you have). Most spring charts will list an installed height for a given seat load. Use shims as necessary to get that installed height after you measure each valve/retainer/lock combination as was pointed out above.
You really should check each spring (or spring pair if duals) for load at the installed height. You engine builder should be able to do this.
IMO, shimming the spring to get more than recommended/needed seat load causes more wear, more friction loss and more stress in the spring (shorter life).
My $.02
You really should check each spring (or spring pair if duals) for load at the installed height. You engine builder should be able to do this.
IMO, shimming the spring to get more than recommended/needed seat load causes more wear, more friction loss and more stress in the spring (shorter life).
My $.02
09-25-2002, 08:12 PM
#6
wrencher
iTrader: (2)
Join Date: Aug 2002
Location: Chicagoland
Posts: 4,762
Likes: 0
Received 0 Likes
on
0 Posts
Re: Explain "Determining and setting spring height" to me.... Thats when a coil spring is compressed to resemble a slinky <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
