Hey guys,

Im putting a ZZ4 Cam in my L98. The heads are already modified, (screw in studs, guideplates and guides milled down) and I was wondering about valvesprings. My dad has some that came with his cam that he didnt use, they are for a 327ci - 350hp out of like a '69 z28 he says (they are brand new replacements). Will these work?

 

Without the spec's its impossible to know if they work or not.

I would just get new ones, with known specs. Comp, Crower, Isky, Crane, etc - all make good valve springs (avoid K-motion, "Z-28" performance springs, no-namers like that).

Don't know the lift numbers off hand, so I can't make any recommendations. Sorry.

 

Unfortunately all I know is they were part of a L79 rebuild kit to make the 327ci 350hp.

Hopefully they are a little better. Ill probably bust a spring and bend a valve.

 

I am also interested to hear some opinions on this one. I am thinking of upgrading my cam to the ZZ4.

The specs on the ZZ4 cam are:
Duration @ 0.050" 208/221,
Valve Lift 474/510,
112 Lobe Center Separation

Right now I am running a Comp Cam TPI specific cam with the following specs:
Duration @ 0.050" 210/220
Valve Lift 480/480
112 Lobe Center Separation

Comp recommends the 981-16 valve springs for my current cam. Can these springs handle the extra 030 lift?
Number of Springs Per Valve: Single
Outside Diameter of Outer Spring (in): 1.254
Coil Bind Height (in): 1.150
Damper Spring Included: Yes
Spring Rate (lbs/in): 417
Inside Diameter of Outer Spring (in): 0.880
Inside Diameter of Inner Spring (in): 0.820
Valve Spring Style: Standard


Comp also makes a cam similar to the ZZ4 which they recommend the 986-16 valve spring.
Cam:
Duration @ 0.050" 220/230
Valve Lift 510/510
114 Lobe Center Separation

Valve Spring:
Outside Diameter of Outer Spring (in): 1.430
Coil Bind Height (in): 1.150
Damper Spring Included: No
Spring Rate (lbs/in): 296
Inside Diameter of Outer Spring (in): 1.070
Inside Diameter of Inner Spring (in): 0.697
Valve Spring Style: Standard

The 986-16 spring will not work with an 083 head unless the spring pocket is opened up. The spring rate for the 986-16 is 296 lbs/in vs. the 981-16 which is 417.

I am no valve spring guru so I dont know what that means. At first glance it looks to be a pretty big difference. Can I safely run the 981's or do I need to go to 986's?

 

If I remember right, the Comp 981 springs are good to about .520" lift. Thats also what Comp reccomends for my cam, which had .490/.490 lift (XE274H).

Might want to double check that though.

 

I read another thread on here, but I am not sure how accurate it is.

The author of the thread claims you calculate the max lift by using the following calculation:

(Installed Height) - (Open Height) = Max Lift

If that is true, the 981-16's would be as follows:
(1.700) - (1.250) = .450

The 983-16's would be as follows:
(1.700) - (1.200) = .500

I was under the impression to took the difference between the Installed Height and the Coil Bind Hieght to get the max lift. Not too sure though.

 

Max lift (capable at the spring) is installed height - coil bind.