How often should you change comp 918 valve springs with a 224/230 .581/592 lift cam?

 

Depending on your driving habits 20k-50k.... My PRC golds showed no float on the dyno just before I sold the heads they were on... 32K, 6500rpm shifts making 2 hp from when the heads/springs were brand new on the same dyno....

 

Awesome, thanks so much thats exactly what I needed to know!

 

springs being worn out or not has nothing to do with if you see float or not on the dyno
and you are pushing close to the max for those springs...they are sugested for no more than .600 lift.. .581 and .592 are getting close. plus your cam likely has pretty agressive lobes being such a small ish cam

I would pressure test them at 10k miles...
if you havent installed them yet.. then pressure test a few before you put them on
Installed Load: 125 lbs @ 1.800"
Open Load: 348 lbs @ 1.200"
Spring Rate: 372 lbs/in

if it doesnt fall within that range, then you should consider changing them.
its going to lose some pressure over time, so off by a few percent is not a big deal... but you have to decided for yourself where the limit is

I've seen springs fail at 3,000 miles, and I've seen them go 40,000 miles

being a single spring.. I would check them more often...
and consider an upgrade to a double spring rated to .650 lift for your next set.
no reason to risk having a single fail and having your motor destroyed by dropping a valve

 

Im not sure on the mileage of mine, but heres what you really DONT want: https://ls1tech.com/forums/generatio...l#post13804872


Should be 125lbs @ 1.8" Measured about 90lbs
Should be 348lbs @ 1.2" Measured about 250lbs

I didnt reach 300lbs even at just before coil bind.

 

and on a double spring you most likely wont drop a valve...you might scuff a piston or make some marks in one...but it wont drop thru unless both springs brake...and usually you would have to drive it for a while with a lot of noise and a lot of misfires before you got to that point... most normal people would pull off the road and shut it down once it started clacking.

 

Im looking at getting a 2000 ss with that cam in it and im just trying to think ahead to all of the precautionary things I want to go through first. What springs would you suggest? Id really like to not have to put alot into the car it seems to be very well built as it is, I just know that valve springs are something you put off. a few bucks spent before equals a ton saved in the end

 

I personally like the Manley Dual Valve Springs good to .650
I've used them in many previous cars and have always had good success with them...
they have always seemed to last me longer than other springs
I have a buddy that has a mid size heads and cam truck, 40,000 miles on the springs...cam gave out first..LOL
when he pulled out the cam he checked the springs, they still had ok pressure on them, but were definitely on the lower side of ok..

 

Although there are those benefits to a double spring, the beehives are a ton lighter, allows a smaller retainer, and there shouldn't be any float with beehives. I would think a daily driver should go around 35-40k miles on a set before replacing/checking them. I'm at about 15k on my set.

 

Ive never seen a single set go for that long... 20k is usually about the limit of a single.. especially being close to their recommended limit on lift...
and you dont really lose anything power wise going to a double...
the couple of horsepower difference you *might* see..is easily offset by the peace of mind and better valve control.

 

I do not recommend going over 25K on a set of single beehives. The extra 10K isn't worth the risk of dropping a valve and grenading your motor. I know people who go 40-50K on them, but I wouldn't if it was my car.

 

Damian, my car has the slp version 918's, stock cam w/ 1.85 rockers... is 25k still the limit on mileage in my situation?

 

I have heard of some pretty high mileage LS1 motors, some approaching 150k with stock motors. I am assuming that they still have the stock behive springs. Why would a better spring only last a fraction of that time? Does an aftermarket cam play that dramatic of a roll in the life expectacy of a spring? I have the TR230 cam in my car with 243 heads and lightweight valves. I elected to use PAC 1518 (beehive) springs and I was hoping to hear that they would last greater than 20k. I havent changed springs on a LS1 while the heads were still on the car. I cant imagine it being too fun to do.

 

the aftermarket springs would last just as long if people stuck with a stock cam lift profile..

problem is that aftermarket cams use a much more aggressive lobe...
its the sudden lift off and closing that causes all the stress.
the more aggressive the cam lobe, the less life expectancy of the spring

 

I'm not familiar with the "slp" version. Were they a dull silver finish, or black w/ a blue stripe?

 

Sure it can..... you will often see a power dip and an uneven wavy graph where it was previously smooth if you have your old graph....

Granted the best way is to pull a couple and test them.

I also agree if you are running a cam close to the max spring rating they will need to be changed more often.

Aggressiveness of the lobe is another factor in spring life.

How close to coil bind are they set up because this affects the spring harmonics is another factor and the list goes on.....

 

yes, dull silver w/ blue stripe. This setup was previously on the car when I bought it. Basically the previous owner bought the car brand new in 02, added lt headers & exhaust, slp 1.85 rocker arm/ 53003 .600 lift spring & retainer package, shift kit, 3.73 gears, suspension. This was all done within the first 3k mi of the cars life... It currently has 14k mi.

 

Damn dude. You've got an 02 with 14K on it? I want it.

The "blue stripe" 918's were prone to breakage, but it was seldom. For peace of mind I'd switch over to the 1218 PAC's, or new revised Comp 918's rated to .625 lift.

The 918's from 02 were known to break. Maybe not on a stock cam profile, but they were known to break with aftermarket camshafts. I'd change them if it were me. The PAC's are cheap. They're $130 from Texas Speed.

 

This. Especially when they are cheap and a easy job......but i'm yet to have that many miles on my car....lead alone on these springs

 

Thanks for all the replies guys! In my situation though I just picked up the car according to the previous owner the build has about 10k miles on it. Im sure I will have to change them at some point i was aiming for when the car hit 100k which means 31k on the springs it has. When I do end up doing it what would you suggest for a daily driver that seldom will see heavy rpm, only when a mustang has a death wish here and there, no drag strip no 5000 rpm between shifts just the occasional romp to prove its an LS1.
Thanks again