Too much Valve lift? What combination is best?

[Pewter02Camaro]

Ive done quite a bit of searchin on this topic and have found lots of sepculitive info but not a lot of concrete evidence. I am running a GT1 cam right now, but am considering going with the GT2. Lift is the same .317 (.507 with 1.6:1 rockers) In the gm shop manuals for our cars it says the stock rocker ration is 1.66:1 that would put my lift at .52622. and I want to buy the yella terra 1.7:1 rockers cuz it is closer to 1.66 than 1.6 is. With the 1.7:1 rockers it puts my lift at .5389. I have Viton Valve seals #105 springs and and will be getting either Comp or manley retainers. My question is this Can i run .5389 worth of lift on stock heads with the afor mentioned mods? Or should i just ditch the idea of using the 1.7:1 rockers with my cam and go with the 1.6:1 rockers. I appreciate any help any of you can give me. Also this is for a Nitrious car, if that helps...

Jeff

[techsan23]

Re: Too much Valve lift? What combination is best?

You will be fine running 105's with the GT2 and 1.7's. If you were running the cam & rockers with stock springs you would probably see some valve float. I am not sure how much lift can the stock head take before the valve guides need to be cut down.

[Pewter02Camaro]

Re: Too much Valve lift? What combination is best?

Thanks for the info. How did you know that anyway? I couldn't find that info anywhere. :bowdown: I am gonna take the heads buy my machine shop today and see how much lift they are good for before i have the guides cut down.

Jeff

[techsan23]

Re: Too much Valve lift? What combination is best?

How did you know that anyway? I couldn't find that info anywhere. :bowdown:

On zz's site they claim the GT2 can be ran with stock springs, and 1.7's don't generate very much extra lift.

[ssms5411]

Re: Too much Valve lift? What combination is best?

The stock rockers measure around 1.66 to 1.7 for people who have measured them so a 1.66 would be a good place to start so you don't go with too much lift.

[Pewter02Camaro]

Re: Too much Valve lift? What combination is best?

Talked to my machinest today. May run into clearance issues with the retainer not clearing the valve seal without milling the valve guide down. Gonna get the Retainers in and take some measurements so we can see what needs to be done next.

[Pewter02Camaro]

Re: Too much Valve lift? What combination is best?

I am also goin to get as many of the measurement specs for the heads as possible for future reference for the sticky threads

[ssms5411]

Re: Too much Valve lift? What combination is best?

On zz's site they claim the GT2 can be ran with stock springs, and 1.7's don't generate very much extra lift.

They said my VS cam could be run with stock vavetrain, I did for years then switched to Comp 105LB springs , modded retainers and Comp 5/16 pushrods and the car felt 2x better, just had more throttle reponse and pickup. Thats why I always recommend upgrading becuase the stock springs get worn and you wind up with 40LBS of spring pressure.

[ssms5411]

Re: Too much Valve lift? What combination is best?

I am also goin to get as many of the measurement specs for the heads as possible for future reference for the sticky threads

That would be great.