DOHC Valve Spring Pressure

[sd_iconoclast]

The factory manual for the '92 Lumina Z34 specifies the open (@1.03") valve spring pressure as 180#, but I cannot find how much tolerance is allowed. Strangely enough, I have found the the spring pressures on my '92 and '95 engines to be amazingly consistant at about 163# at 1.03". Even more strangely, the spring pressures on my '91 engine is very consistant at about 180#. Did GM change reduce the spring pressures? Is 163# OK or do I need new springs?
The three engines I describe all came out of the junkyard. The '91 and '92 each had about 150k on them. The '95 had about 100k.

[SappySE107]

The 96 springs are supposed to be 160# @ 1.03 and 65# at 1.4". I dont know what year they switched but I think I can tell the difference between higher and lower spring pressure on my cutlass past 6500.

[sd_iconoclast]

Does anyone know where to buy new 180# springs at a good price?
Does anyone know where to get good aftermarket springs?
What about just shimming the old springs?

[SappySE107]

I am buying some shims in bulk. I am also going to test the springs GM currently sells, because they are definetly not stock 91-97. I have the specs in an excel sheet, so here are the specs I have so far.

96 springs

Free Length 1.6551
Installed 1.4 #65
Max Lift 1.03 #160

Compressed to stock 1.4 @ #80.28
Compressed to max 1.03 @ #175.40



91-95 springs

Free Length 1.6551"
Installed 1.4 #75
Max Lift 1.03 #180

Compressed to stock 1.4 @ #92.64
Compressed to max 1.03 @ #197.027027

New Springs

Free Lenth 1.762"

Dont know anything else. Im also going to get the coil bind for them all since we will be needing that information as well.

[sd_iconoclast]

That info would really help me out. Could you also include the part number of the new springs?
Have you ever seen 160# springs on '91-'95 engines? My '92 and '95 engines both had them. Only my '91 had 180# springs.
I am in California. Maybe the springs were derated for Fuel economy.
I guess we all need to check them.

[SappySE107]

I havent had any tested yet, so I don't know if my other heads have the stronger spring or not. The number can be found for hte 97 monte carlo on www.gmpartsdirect.com.

[Anonymous]

Ben correct me if I am wrong.

Currently our(my) springs are good to 7150 with no float. Now the only reason to get stiffer springs is for higher rpm's so float doesn't occur correct? Becuz when i order my new springs, I do not thing they need to be any stiffer than stock becuz the stock ones already go to 7150 no problem, and since I don't plan on exceeding that....

Am I wrong here? Is there another reason for stiffer springs?

[SappySE107]

The 180# springs are good for 7150. Boost or more lift would be reasons to go stiffer, or more RPM of course.

[sd_iconoclast]

I just ordered a couple replecement springs from my local chevy dealer. I will test them when I get them and post the results.

[Anonymous]

Ok I wil not have boost and I will not be going past 7150, so that leaves more lift. I may get slightly more lift with the reground cams. I don't know yet. It still has to be decided on specs and stuff.

[SappySE107]

Im going to be testing some different cams this summer with the specs I think will show the best topend per low end hit. The low end wont suck though for a 5 speed, or with some other mods to the engine at the same time.

[sd_iconoclast]

I notice that the Sealed Power replacement spring (part # VS1562) has an open pressure of 172# @ 1.03" and a closed pressure of 72# @ 1.4".

[Anonymous]

Im going to be testing some different cams this summer with the specs I think will show the best topend per low end hit. The low end wont suck though for a 5 speed, or with some other mods to the engine at the same time.

Ok than I will wait till this summer for cams, that way I know which ones I want. I want a powerband from 4-7150, I could care less about anything below 3k. I don't care if I lose a lot of power down low as long as it maximizes high end.

[SappySE107]

Then I already know what grind you would want.

[Anonymous]

Do you have the specs liek the lift and duration???

If so plz PM me, it would be easier to give some cam shops that info so they can do the work.