PI HAT

I have an MS4 cam that is rated at.651 on the intake valve lift. I recently broke a comp 921 spring on the exhaust side the other day that is rated to hold .650. I wasnt racing the car but I think it was my fault for reving it up to early. I just ordered a set of Patriot Gold Duel Springs rated again at .650. I dont really have the money right now to order the Patriots rated at .660. Do you guys think I will be OK?????????

adam1803

iTrader: (65)

I usually like to have at least .025" less then what the spring is rated for, just personal preference.

Black FormulaLs1

iTrader: (10)

i would definatley make sure i have room for overrevving...always have that extra cushion...always! and besides if youw ant to go with a bigger cam later you have enough valve spring to do it

PI HAT

I keep telling myself that it will be OK but.......At about what RPM do you think springs begin to max out at? .001???????

PREDATOR-Z

This is the info you should be looking at to match the cam not lift rate.

Technical Specs: Patriot GOLD dual springs

Install Height: 1.800"
Max. Valve Spring Lift: 0.650"
Spring Pressure Closed: 135 lbs. @ 1.800"
Spring Pressure Open: 375 lbs. @ 1.150"
Coil Bind: 1.090"
Retainer Material: Titanium

So you should call TSP and get the cam requirement to see if it is within the spring parameters (seat pressures)
If close, you can always shim the springs to raise the pressures (this will reduce spring life but will work fine)

35th SS

iTrader: (2)

spring failure here 2 weeks ago.trex running crane duals good to 650 lift.only had 6k on the clock and busted #2cyl.exh.vlv. spring outer.got on it hard 4th gear on the freeway.now running prc duals 660 lift all back together on the road again.if I was you I would call TSP.

willyfastz

You should never buy a set of springs and JUST install them. You should check the info that Predator Z posted above and set the springs up to match what you need. Changing the installed height of the springs changes the open and closed pressures of the springs so you can easily match them to your cam.

And was the installed height checked on the springs that broke? I bet the installed height was to high.

KCS

iTrader: (20)

You revved it too early? Like before operating temp?

I think if the springs are set up with proper clearances, you'll be just fine. You'll know if you need better springs/valvetrain when you go into valve float, lol.

danhr

iTrader: (18)

I run patriout golds on my .663 lift cam

Shawn MacAnanny

iTrader: (12)

I'm running patriot golds and my cam is .651 on both intake and exhaust. No problems so far. I've put 18 hours on the engine but i am very careful not to rev the engine above 3500rpm or so before it is warmed up. The cam measured is actually .647" lift not .651 as advertised too. Atleast mine was. If you havent bought springs yet get the patriot extremes for .660. I had already bought mine before i found out there was a .660 version available.

vettenuts

iTrader: (4)

Advertised maximum lift is a guidance number only. You need installed height and the rest of the spring information, along with cam requirements for seat and open force, to figure out the valve spring installation. Tolerance stack-ups will be more than the 0.001" you are talking about, you really need to get the installed height first and work from there otherwise you are guessing and throwing money at parts you may not even need.

vettenuts

iTrader: (4)

Were they Crane 832's? What was their installed height? Those springs setup very low for seat force and will bounce the valve if not correctly setup. They are designed to be shimmed for the correct seat forces.

willyfastz

I think the biggest part just install the springs and have no clue how they should be set-up.

PI HAT

I bought the cam, oil pump, pushrods, springs, seats, and retainers as a package from Texas Speed. I got with TSP and asked about the L66 stage 1 heads and they said they were good to go. I didnt do any measuring after the install because to be honest, the whole valve float, spring preload and calculations confuse me. I just took the word of the guys at TSP.

PREDATOR-Z

Normally TSP set them up with PRC springs, I find that a bit odd.
And 921s need shimmed from coilbind for that type of cam.

vettenuts

iTrader: (4)

If you can get the installed height the rest of it can be sorted out. The two things you really need are installed height and seat value. The rest can be computed and if you need help just ask.

ZFSix

iTrader: (14)

I ran a .612 lift cam on old Comp 918s (.600 lift) for a while. Never had an issue. Sold the springs to a friend of mine and they're in his GTO now with a smaller cam, he hasn't had any issues with about 5k miles so far.

JPH

iTrader: (2)

INSTALLED HEIGHT is your key here. You will never see .651 at the valve anyways, because lifter absorbtion and pushrod deflection and spring defelection anyways.

PONTIAC SLP

iTrader: (3)

run with patriot extreme 660 lift