When to replace valve springs?

[TR Custom Parts]

Here's a question for those of us with low mileage cars. When should valve springs be replaced? Just because a car has only 22,000 miles on it like mine, they have been in there for 15 years now. I just think of all the time the motor was just sitting there in storage with some of the springs compressed, it only had 4700 miles on it when I bought it in 95.

 

[turbo buicks]

i dont know does your car feel sluggish? ive heard that weak valve springs make it rev up slower and anyone i see asking about stock ones everyone tells them to get new ones anyways. its either now or later i guess

 

[Russ Merritt]

I'd do it! Cheap easy job. You can change the valve seals as well.

 

[salvageV6]

Most likely 10 years ago Mark!

I can test your low mileage originals at work some day for ya! Just bring a few to the Cruise Night sometime.

I have Kirbans compressor tool if you need it too.

Comp. Cams 980's no cups. B+B can get them.

The stockers?

They are dead Jim.

Bet around 65lbs.

 

[d0n_3d]

you know everyone says to change the valve springs in these cars as soon as you can but i am going on 90k miles on my GN and i can still rev instantly and rev up to the redline at around 6000 if i want...car pulls hard at the top end still and car runs like it is still new..

 

[turbo buicks]

dang d0n_3d, 6K, i thought redline was around 5200! you did say you babied your car in a previous post somewhere awhile back so i bet thats why your springs seem good.

 

[gnturbo]

mine feels a little flat on the topend of the quarter.I have 76k miles I was wondering if new valve springs might snap it up a little.Ya think?

 

[Ormand]

Stock Tachometer

Pretty easy to hit the redline, and then some, with the stock tach. Mine reads about 1000 rpm before I ever start the engine! The stock cam, and springs, are not designed to take you to a real 6000 rpm, even when brand new. The cam doesn't have the lift/duration to go that high, and the springs are only 80 lbs, on the seat, and about 180 open. Not enough spring to keep the valves from floating at about 5500-5800 rpm.

 

[Nick Micale]

Originally posted by BuickGn Boosted
Here's a question for those of us with low mileage cars. When should valve springs be replaced? Just because a car has only 22,000 miles on it like mine, they have been in there for 15 years now. ..........

Do you have a good reason to change them? Because they are 15 years old is not a good one. My Riv is 30 years old and still no reason to change them.

Only good reason to change them is when you cannot rev over 4000 RPM and you need to, like when racing.

Reasons not to, dollars and time, chance of screwing up something, wiping the cam?........

 

[turbo]

I agree with Nick. A well known engine dude that most of us would know said the same thing Nick said. Maybe he'll reply.

I've never met Nick, but I've been around here from the beginning and EVERYTHING he's said has always seemed to be right on target. He knows his ****e!!!

I personally have 146,000 + miles and it revs over 5,000 rpm in a snap. According to DirectScan it shifts at 5200. I've used a synthetic oil since the car was new, so maybe that's kept the oil from overheating and causing some type of thermal metal spring fatigue?

Has anyone dynoed or checked out 1/4 mi. mph as to how much hp you would lose at 5,000 rpm with say a TA49 or TE 44 before and after spring change at say...22 lbs of boost?

I wouldn't think it would be over......15-20 hp at most?? And if you can run 22lbs of boost on the street even with a stock turbo, you're going to be kicking major ass, on most cars that are out there. I doubt that another 20 hp is going to help on the street. Unless you have some real nasty meats, you'd lose it in traction anyway. I think we've all been there. NO FLAMES. These are just my OPINIONS.

I know a guy who changed springs...I think they were 100 pounders and wiped the stock cam. And I don't think he was using a synthetic oil. So, maybe it has to do with what kind of care and treatment the engine has been through. Like the kind of OIL?

I think I'll wait until I tear the engine down. I don't want to create any problems. Oh, I run a TE44 and even with Z rated tires, on most street surfaces, I can hear a little chirping all the way through second and a little into third. If I had more hp I don't know how I could get from point A to B without doing a bunch of suspension work or street slicks. I have the typical rear...boxed and bagged.

I just thought of this. What do you think is the max. hp you can run on the street, with street tires...just a good vr or z rated tire...
and still have TRACTION....350 hp? A little spinning would be okay! Maybe that should determine whether a guy needs a spring change or not!

 

[Ormand]

Test Results...

Somewhere, on one of the boards, there are some numbers from someone who actually tested valve springs that had been in service for 20,000 miles or so. For 15 years, or more, the springs have been under constant compression. When the engine is not running, some valves are partly open, just sitting there. A couple may be wide open, under full compression. The high dollar alloy springs used in racing resist creep pretty well, but the cheap springs used in low rpm engines by GM may lose some preload due to creep, after all these years. The test results showed there was a significant drop in seat pressure. However, like Nick says, if it doesn't bother you, don't worry about it. The stock cam is not a high lift, high rev cam, the auto trans shifts at about 5000, so valve float may not be a problem worth fixing.

 

[jojo]

Thats funny, just took my car out last night and blasted it coming down the on ramp. According to the scanmaster mine shifted from the 2-3 shift at 4850, and these are pretty new springs from Kirbans about 9-10 months old but i dont put a **** load of miles on the car. Is there something wrong with those r,s??

thanks

jojo

 

[CaPPY]

That sounds fine to me. That's what my Scanmaster shows at the 2-3 shift!

 

[bishir]

Scanmaster tells what RPMs your car shifted at? I have a SM and I didn't know that!

 

[strikeeagle]

Does the ability to rev to a particular RPM, say 5200, imply that the valve train is in good control, and that HP is not being sacrificed by weak springs???

 

[getchasum]

TR Value Spring Info

These numbers are from a 1996 issuse of GSX-TRA. Test was done at recommended installed height of 1.71. Note GM recommends a minimum seat pressure of 78 psi.

Spring Type:

New stock GM.........................78-81 psi
New Comp Cam (979).............86-88 psi
Stock w/30kmi. (raced often)....45-52 psi
Stock w/32k mi. (daily driver)...55-61 psi
Stock w/62k mi. (raced Often)..44-51 psi
Stock w/65k ( daily driver)........49-58 psi
stock w/98k mi. (daily driver)....45-56 psi
stock w/68k mi (overheated)......41-48 psi
Comp Cam w/34k mi (979's) ........74-80 psi

Test results were on all springs and these numbers were the range that was found. You can see that even a low mile car in 1996 sping pressure was down. Just recently changed the springs in mine, top end feels a little more pepy to me. These numbers anwsered the question for me.

 

[Ormand]

Shift RPM

Have to be careful typing "shift", I keep leaving letters out. The rpm is a function of transmission condition. The governor springs vs the pump output pressure. I think the rpm for the shift changes with gear, too, but not sure. Also, there are some who say the adjusting the TV cable will affect shift rpm. 4850 sounds a little low to me, but I'm not sure. I mentioned 5000 in my previous post, because that's what I remembered from anothe post, months ago. And my memory ain't what it used to be. Transmission gurus, where are you?

 

[TrAb]

So weak springs wouldent have anything to do with a car with slow acceleration?

 

[bmackinnon]

No...more to do with a car that wouldn't rev up top due to valve float.... and WOW! way to revive an OLD post!!! Good info in there from getchasome!

 

[TrAb]

Yeah im used to being yelled at on other forums when you make a new post so i try to do a little search before hand...