Danspeed1

iTrader: (1)

The last step before I can bolt my whole engine back together is to check the valve spring height.

To give you a little background, I had a bone stock LS2 Vette I installed a cam into with a .625intake/.625exhaust lift, morel 5206 linked bar lifters, had cylinder heads mildly ported, bigger 1.60 exhaust valves on 342 heads; topping it all off with a Magnuson M112 supercharger with about 8-10lbs of boost on pump gas.

I was going to check the installed height today of the valve springs, however I just had the heads done along with a nice valve job, so prior to doing so I stopped by the machine shop to see if I could get any info.

Good news is they did the work for me.

This is more of an opinion question as I already spoke with both the machine shop and Lunati cams and although they say their is no specific tolerance on valve spring installed height, I was told my height was just fine. Here are the measurements:

Valve Spring Specs from Lunati:

O.D. 1.306"
I.D. .676"
Max lift: .660"
Seat load: 153 lb/in at 1.810"
Open load: 400 at 1.150"
Rate: 379 lb/in
Coil bind: 1.100"

Actual Valve spring installed height measured by machine shop, 1.82 - 1.83
open load @ 400 LBS measured at machine shop

Like I said, just interested in opinions. The big thing Lunati tech support was concerned with was how high an RPM I was running. I figure 6500-6800. They said if I keep it at 6500 the installed height should be just fine. They also said its not so bad lowering the spring pressure a few pounds considering I am "only" running a .625 lift VIA the installed height.

I don't want any issues at all with this motor, however these guys have far more knowledge than I do. Like I said before just looking for some opinions.

DG

TurboBuick6

iTrader: (2)

You should be fine with the setup. If your concerned with anything I would get a spring with a higher rate. Something around 410-440 lbs per inch.

Tainted

iTrader: (9)

are you on stock rockers? If you are, pushing the open seat pressure past 400lbs is a no-no but its close enough where you should be fine

WKMCD

iTrader: (2)

You are .085 away from coil bind. (Installed height - lift = distance to coil bind) Most recommend .050 of coil bind to achieve max open spring pressure. You can shim them .030-.035 to get there.

Just my $.02

Sales2@Texas-speed

iTrader: (5)

Fixed your equation in bold.

Danspeed1

iTrader: (1)

Stock rockers,

Maybe do the trunion upgrade next year, but no plans for yella's or anything like that,

DG

Danspeed1

iTrader: (1)

I like that equation... writing that down for the future,
Thanks,

DG

Danspeed1

iTrader: (1)

This might be a stupid question, however isn't the open seat pressure effected by my lift. Lift at .660 puts me at 400, I should be less anyway at .625?

More interested in whether the added spring height is actually beneficial for my setup, or detrimental; I really have no reason to shim it down to lets say, 1.800, as I am not running this thing to 7500 where I really think I have to worry more about valve float. Most the stock springs will run to 6500 (on a stock cam of course)

DG

Sales2@Texas-speed

iTrader: (5)

Seat pressure is the pressure exerted on the retainer/valve when the valve is closed all the way. It is always rated at a certain pressure @ an installed height. Then you have the open pressures, which are rates at a certain pressure @ a certain height (installed height minus lift).