i tried searching this. if my cam lifts to .480 and on the gt40(non-p) has 480 max lift springs....do i need newer(bigger) springs? also is 480 lift too big for stock springs? is that what is stopping me from revving past 4k rpms? if not how to i check to find out if its something else

 

bump

 

the spring rate is in relation to the theoretic valve lift.. that would be ur cam lift x ur rocker arm ratio. ur best bet is to get the answers thru the manufacturer. Its hard to answer ur questions when i dont have the specs to the springs or the cam.

 

the spring is stock, what is max lift on stock....how is that hard to determin?

 

i need to know because i just wanna know what stops me from going over 4krpms, it feels like the throttle sticks after 4k or somethign and it doesnt go any faster...like it tops out

 

Might be a bent pushrod or valve. I overrevved one night racing a Grand Prix (smoked him) but the next day I didn't have the power I once had and it wouldn't rev for me. Hope this helps.

 

well all power is normal until 4k and then it doesnt really build after that and when i reach....4200 or 4400 ish it feels like...i dunno its hard to explain, like it feels as if the throttle sticks but thats not what it is. so it dunno what it is. i doubt anything is broken but something isnt working right. any ideas? anything i can try to give you guys a better idea what im looking at.

 

The stock springs are "technically" good to ~.500 lift, BUT, you have years of use/abuse on them + xxx,xxx miles as well. I would strongly recommend you upgrade valve springs any time you change heads or a cam, assuming the heads are used as opposed to new or reman'd.

That may not be the problem though...I would check valves and lifters as well.

 

could this be my problem with not going past 4k rpms? is it floating vlaves? or could it be something else? i have new spark, cap, rotor, and plugs. fuel system is stock, the rest of the ignition is stock. all my other mods are listed in the sig.

 

could be fuel delivery problems, more specifically a broken baffle in the fuel tank, lodged under the pump.