Another 105# vs 90# question

**PWNED** · 09-13-2014

I have used 105#'s in the past on a 1.9 rocker build and an s1x build with no issues. Years later I am trying to learn the actual differences. I think I found some interesting info, but I will have a question after this is read.

(Random Google finding)
As for wearing out the tensioner. if you install the yellow or pea green ls6 springs these springs will wear out the tensioner very quickly due to the hight 300lbs spring rate they have. however blue ls6's will work fine with the stock tensioner. they have 250lb spring rate and were used only on the 01 z06 vette. they springs are 22lbs heavier then stock and work well with 1.9 rocker cars and small cam cars. I have one of my gtps running yellow/pea green the other is a 1.9 rocker car with blues. the yellows will wear your tensioner out in a matter of 7000-10000 miles. quicker if you drive the car hard and take it to the track a lot. This is proven fact on 3.8's with the stock timing chain and tensioner set up.

Do not bother installing ls1 springs into the car they are rated 2lbs heavier then stock l67/l36. Ls1's are 230lb spring rate and the stock 3.8 is 228lb spring rate. this is a sideways step and not an upgraded.

there are two types of ls6 springs. three if you really want to get technical about it.

there are blue ls6 (rated to 250lb spring rate) good for 1.9 rockers, small cams

yellow or pea green ls6 springs(rated to 300lb spring rate) bigger cams but still under .550 lift.

ZZp's site below
90# springs are GM LS6 springs*. The LS6 comes from the factory with .550" of lift and spins to 6500 RPM to give an idea of what the springs were made for. Seat pressure is lower than the Comp Cams 105# springs but spring rate is higher so they do work well for aggressive ramp rates. There springs work well with the VS and NIC cams when shifting at 6000 rpm. Because of the higher spring rate, timing chain dampener life is lower than with the 105's. 1.80 recommended install height

What is seat pressure? When will this need to be a factor?

If a 90# has a higher rate than a 105# then why do most think buying a 105/130 is better than a 90? What is the rate of a 105# then?

When a ramp rate is said what is that? In general for high revving motors you will want a spring with a higher spring rate?

**SgtMarshal** · 09-13-2014

seat pressure is the pressure the spring applies to the valve when installed at a certain height. every spring has a range of pressures all the way from no pressure to the max amount when the spring is compressed fully. when you get to a certain spring height, you get to a point where the spring will start binding. spring bind is a bad thing and is a contributor to valve float.

I don't know why the 105's have a lower spring rate than the 90# ls6 springs.
I don't know what the ramp rate is either.

I've been wondering about the difference between the 90 # and 105 # springs my self. I will be installing 1.9 rockers and I have 90 # springs, but if I need to do 105's for better longevity I need to figure it out soon.

**Iceman6669** · 09-13-2014

There's seat pressure and lash rate. Seat pressure is how much it's pushing up and lash rate is how quick it returns to installed height. I've heard it's the lash rate that is hard on the chains. But I know lots of guys who put much more then 7-10k on a chain with 90# springs.

**freneticburn** · 09-16-2014

I've been running the yellow 90#ers in my VS cammed, top swapped Bonneville for about 20-30k miles and I'm still good. Shift points at 6k. It's daily driven all year long too and although I don't drive much I drive mostly city miles and in short trips.

**BillBoost37** · 09-16-2014

Seat pressure is the pressure of an installed spring with no additional forces being applied other. Info on that http://www.cranecams.com/faqview.php?s_id=33

Rate in spring is how much force it takes to open the spring, the more force the more it abuses the rest of the valvetrain and chain/tensioner. Info on that: http://www.cranecams.com/bulletins_listview.php?s_id=17

Ramp rate is how fast the camshaft opens the valve. Info on that: http://ls1tech.com/forums/generation...ramp-rate.html

**BillBoost37** · 09-17-2014

Forgot to mention yesterday that when you get different springs, you should consider that stock install height is 1.72x" and modded retainers gets you in the 1.78x" range. That's about 20 thou of preload that can change the pressures.

To properly install 1.800" springs you should have the spring seats machined.