Comp Valve Spring Question

[Joel Russo]

If you were to change valve springs on a stock motor with stock heads and cam.... would you use the Comp 980 or the Comp 981 springs?
 
980's are rated at 92lbs at 1.700 and the 981's are rated at 105lbs at 1.700"
 
When you change the springs, and eliminate the stock spring cup, do you need to use shims? 

[earlbrown]

To do it right. You need to measure the height on each and every valve and measure each spring and shim from there.


To just shotgun them on the car, I'd do a search and find a pattern for what other people did and got away with.

[motorhead]

99% sure the combo is 980s without the cups.

[Steve Wood]

99% sure the combo is 980s without the cups.

yes

stronger springs do no good whatsoever on a street car with a stock cam other than to accelerate lobe wear

[Forzfed]

To do it right. You need to measure the height on each and every valve and measure each spring and shim from there.


To just shotgun them on the car, I'd do a search and find a pattern for what other people did and got away with.

Listen to this guy!  If you want to do it right, this is the proper method.

[Scoobum]

If the engine's bone stock and you're not gonna be beating on it then 980's without the cups are fine.

[Joel Russo]

Thanks guys.

[trashmechlv]

I recently did the 980 springs on my engine that had original springs with cups. One of the best and cheapest mods I have done to car.

[Joel Russo]

I recently did the 980 springs on my engine that had original springs with cups. One of the best and cheapest mods I have done to car.

Assuming you have stock heads, where did you see improvement with the new springs?

[earlbrown]

The engine will quit falling on it's face before the shift points.

The downside is the valve sealing surfaces will still be all black and scorched from years of not sealing.

[motorhead]

I am pretty sure one of my valve seats/valves is fried from years of abuse.  Which is contributing to low compression in one cylinder... but, damn do fresh springs help a lot!

I am still pushing 25-30psi on the backside of those valves and it is holding over 10 years later.

[earlbrown]

It's amazing just how much you can get away with on these engines. 

They defiantly aren't the delicate little snowflakes some make them out to be.

[trashmechlv]

The engine will quit falling on it's face before the shift points.

The downside is the valve sealing surfaces will still be all black and scorched from years of not sealing.

Well said, my car wouldn't even rev to 5 grand. After the springs it runs much stronger all the way to the 5 grand shifts now.

[Scoobum]

I recently did the 980 springs on my engine that had original springs with cups. One of the best and cheapest mods I have done to car.

Assuming you have stock heads, where did you see improvement with the new springs?

The engine will rev out cleaner and quicker.

[Joel Russo]

Looks like there's no real downside to upgrading the springs.... On the "to do" list for the winter.
Thanks guys!