Valve Spring Longevity

**98formy** · 08-09-2007, 10:28 AM

How much longer would dual springs(921's) last vs. single(918's) with a 232/234, .595"/.598" 112 lsa cam from texas speed

**dragulals1** · 08-09-2007, 11:27 AM

I just bought that cam. I think the dual springs are necessary for the high lift.

**nhraformula** · 08-09-2007, 05:36 PM

you want duals for that cam. change at about every 20k

**MNR-0** · 08-10-2007, 11:43 PM

About 1-2K more than the single springs. You can't measure valve spring integrity at just full lift or on the seat. 0.2" is where its at.

I replace my dual springs every 10K - no more. If I was running 918s then every 5K. When the spring starts to fatigue, its over. It still may be servicable, but upper RPM valvetrain control will gradually diminish.

Depends what you are willing to live with really. Street use is enduro and very hard on springs.

**Eddie 70** · 08-11-2007, 12:53 PM

I know this is apples and oranges but, why do stock springs last for 100k miles and these aftermarket springs done with only 20k miles on them.

**MNR-0** · 08-13-2007, 06:53 AM

Originally Posted by Eddie 70

I know this is apples and oranges but, why do stock springs last for 100k miles and these aftermarket springs done with only 20k miles on them.

Stock springs don't last the factory floor.

What's your definition of a spring that's dead? Valvetrain control or it aint visibly busted?

**Eddie 70** · 08-13-2007, 05:50 PM

Originally Posted by MNR-0

Stock springs don't last the factory floor.

What's your definition of a spring that's dead? Valvetrain control or it aint visibly busted?

I don't normally give my vehichles too much hell. My last truck had 140k miles on it when I traded it. It still ran good, drove good, burned no oil. Those valve springs probably could have been changed but they still did their job. I am sure for high revs they were toast though.

**INMY01TA** · 08-17-2007, 05:47 PM

I would go with either PRC's or Patriots dual spring kit. They're more than up to the task and about $300 cheaper.

**gillbot** · 08-24-2007, 11:56 AM

PAC Racing has a new spring that can handle more lift and they last longer than the old 918's. Maybe check them out.

**jrgswhitels1** · 08-24-2007, 02:44 PM

Springs lose their strength over time mostly because they stay compressed!!! When you couple that with heavy driving or heavy valve action (cam), they will lose its original pressure. Rest assured all springs will eventually lose their seat pressure no matter what height they were installed.

**310stanger** · 08-24-2007, 03:45 PM

i agree with everything said except for the fact of springs only lasting 20k or less. in some cars is this the case? sure, it can be. but I'm very comfortable in saying that for the average street performance driver, driving a performance v8 with performance cam and springs, you will be able to go much longer then 20k unless you are driving like a complete animal banging the limiter and floating valves. theres no way in hell you are gonna see me changing out my double springs any sooner then every 30k MINIMUM.
Examples of people that should change them 20k or under would be guys that race frequently, guys that abuse the car and bang the limiter and maybe cars with HUGE cams.

**jrgswhitels1** · 08-24-2007, 03:54 PM

It really depends on how much piston to valve clearance you really have, vs. spring strength and stability over time! You runn'in 918 Comps beehives with say lift of .565, Youll be OK and see 50,000 miles easy before anything serious starts to happen. THATS, of course you take care of your ride and dont beat like Michael Jackson in his crib on a weekend wearing a shirt saying "Im innocent, re,re,really!!!" LOL!!