I will be installing ZZ3 cam with recommended springs.

I have the specs for those springs. They are
1.273 inch in diameter and 1.16 inch in heihgt

My question is:

1. Do I have to get new seats for these springs (stock diameter is 1.25)

2. How tall are the stock springs? Do i need to get taller valves?

Can somebody answer that?

Thanks

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89Iroc, 305 TPI, WC T5, 3.08 Posi, Headers, Hooker Y-Pipe, 3 inch over the axle, Flowmaster 80, No Cat, Aluminium Driveshaft, Ported Plenum, Air Foil, K&N, AFPR, All free mods,

 

spring seats are cast into the head, all you can do is machine the seat larger, i doubt if you need to. the installed height is controled by the seat to retainer distance. you won't need taller valve covers. you will want to trash the factory rotators and cups and go with aftermarket retainers.

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

Thanks Ede.

 

They will fit in the stock spring pockets. .023" difference is no big deal for diameter.

As for the installed height, there's not enough info to say from what you posted.

BUT..... what I can tell you is this:

Stock spring pockets when used with stock valves have an installed spring height of approximately 1.75". That's the distance from the floor of the spring poscket to the bottom of the retainer, with no shims installed. So your spring "height" dimension is likely the "coil bind" height of the spring.

P.s.- the exhaust valves with the thick valve rotator/retainers STILL have the same installed height as the intake side! The spring pocket is machined slightly deeper to make up for the thicker retainer. So the springs on the intake and exhaust are the same, no difference in height.

Anyways- take the installed height 1.75 and subtract the "coil bind" height 1.16 and you'll get .590". That's the spring's max. lift. But you NEVER get closer than .025" to coil bind or you'll bend/break stuff. So that's .565" max lift. But that's just what the SPRINGS will take. With stock heads the retainers will hit the valve guides at much lower lifts on stock heads- .470-.480" is about it with a stock configuration in most cases. Measure EVERYTHING before you make assumptions about whether the heads will take the cam you are planning on putting into it!

 

Thank you Damon for your valuable information.