Hi, I would like for someone to explain what the numbers mean as far as what kind of pressure to look for when purchasing springs.

I am going to be running a ZZ4 cam which has a potential lift of .544 with 1.6 rockers. I am going to be using Aluminum L98 heads. Can someone recomend a good set of springs for use with this cam, and can you explain why you would choose them over another. I see so many different kinds it very confusing Oh a part# would be great.

By the way I don't care if I have to machine the spring seat, it would probably be a good idea anyway.

TIA

 

easiest thing to do would be to run the springs gm recomends for this cam, or comes on the zz4 engine.
just a guess but i'd say 73100 from lunati would work
125# installed
162#@1.75
330#@1.25
coil bind @1.1
od 1.550

------------------
ICON Motorsports

1st & 3rd
MM Black Diamond Lodge 538 F&AM

 

Comp cam #987
130@1.800
325@1.250
bind@1.150
od 1.475
spring rate = 355

These springs are recommended for their solid lift cams ranging from .507 to .570 lift. They don't offer a hydraulic cam with the amount of lift you plan on getting to do a spring comparrison. Shouldn't matter if the cam is solid or hydraulic. It's still considered a flat tappet cam.

 

You will need more retainer locks-guide clearance and with that lift you will need larger springs which means the spring pockets need to be enlarged for the springs.

The springs above are fine if the installed height is correct. Make sure someone checks that.

 

I went over to the Jim Pace website and it says to use the LT4 springs which are used on the ZZ4 heads. I noticed the spring diameter is larger than the stock 1.25 L98 aluminum heads used so I will go and get my spring seats machined.

Question...Lets say someday I want an even larger diameter spring, can I have the seats machined more than the diameter of the LT4 springs? What would I have to do to make it work now with LT4 springs?

One other question...I see they sell shims as well, do I need them and what size would I need?

TIA

 

How much you can machine them depends on the head. I cant remember how much space there is on the vette head.

Shims depend on the head too, and will vary on each and every valve in most cases. There are too many varibles that change the installed height.

 

If I don't know anything about checking installed height, then do you think I should provide the machine shop with the springs, retainers, and locks that I want to use and let them just machine the head as much as it will allow staying inside the safty margins, and also let them provide the correct shims when they are installing all of the parts?

What size push rods am I going to need? I know they have to be hardened because of my guide plates, but they sell them in different lenghts and I don't know which size I need.