CalSpeedPerformance

iTrader: (64)

Ive got a set of heads coming from Texas-Speed that im putting together (first set of custom LS7 heads that ive done). So im thinking about trying to cut costs down on this motor by running stainless hollow stem valves with them. ($880 cheaper, plus i dont know how reliable the tit valves are with 1000+ rwhp on boost)

Im worried about valve float problems due to the size of valve 2.200" with quality stainless valve. This setup is a turbo setup so I will not be running alot of camshaft and im looking to have a 7000rpm shift point setup to increase reliablility etc.

The cam im thinking of is approx 239/250, with around .609/.645 @ 114+3
which i think with a set of PRC Xtreme Gold springs should have no problem with valve float on the intake side. The 1.61 exhaust stainless valves are no problem...

Combo:

PRC LS7 CNC Cylinder heads (400cfm)
Yella Terra LS7 Ultralight-shaft rockers
S-91 turbo from Jose @ FI

Jason 98 TA

iTrader: (4)

I'm working a little bit on a hollow stem option that I will have more info on later this week. I'm going to see if we can get a good option between the steel & titanium valves.

I'll keep ya posted!

Haans249

iTrader: (24)

Where exactly are you getting these?

CalSpeedPerformance

iTrader: (64)

I think I got the first set out from Yella Terra...i got them in my hands about two weeks ago

ramairws6

iTrader: (33)

Is this a dual spring?

Ryne @ CMS

iTrader: (10)

i tried stainless valves in the past on the ls7 heads, i ran into valve float at about 6-6200 rpm, on a na motor with extreme springs, that valve is really heavy for that spring to control in my opinion. i would at least opt for a hollow stem valve, or custome ti valve setup that would be more reliable

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Fwiw, we have run ET LS7 heads with steel valves to 7,500+rpm with springs set up at 200/435, stiff pushrod, stock rockers.

Ryne @ CMS

iTrader: (10)

what springs? is it still a 1.290" spring?

Stang's Bane

iTrader: (22)

Is that the full size ones or the 4.0 bore ones??

Very nice either way.

toneloc60

iTrader: (7)

I was running a set of Manley Nextec springs with Ti retainers and super 7 locks with a set of Harland Sharp roller tip rockers on my LS7 heads with Ti intake and sodium filled exhaust valves. The springs were good to .650 lift and tested 135lbs at the seat, 385lbs at .650 lift. But, due to the extra tip weight of the roller tip rocker, the valves would float at 6300.

Becuase of that, I would guess you're going to have to run some pretty stiff springs after having the Yella Terras and the stainless valves. Probably too much weight for 7000 without really stiff springs. But, I don't know what the PRC Xtreme Gold springs have for pressure.

Mr.MartyStone

iTrader: (12)

You're going to have to run more than 135 on the seat with that heavy of a valve. Try shimming them to around .050" or so before coil bind.

toneloc60

iTrader: (7)

Shimming didn't work for me, I had to go with stiffer springs. To be honest, though, I don't even know what springs I'm running now. It was on the dyno that we realized the valves were floating and I wasn't there when the builder ordered and installed the new springs. I was just happy as hell when I heard what we ended up making for power I forgot to ask what springs he ended up going with.

CalSpeedPerformance

iTrader: (64)

The yella terra ultra-lights's are lighter on the tip than a stock rocker actually. Harland sharps are much heavier than a YT.


Anyone have a suggestion for a good double spring with similar specs of 200/435 pressures to fit on a ls7 head?

Mr.MartyStone

iTrader: (12)

Try a step cut on the valve pocket so you can step up to a 1.550" diameter spring. Your options expand greatly at that size.

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The spring I like to use is the PSI CT1225 ML. I feel it's ideal for a hyd roller turbo car as it has a low rate of 393lb/in which allows you to set it up at a high seat pressure (200@1.800) without having excessively high pressure over the nose (435@1.200).

http://psisprings.com/index.php?opti...ask=view&id=17

Only downside is price as the springs and retainers are rather expensive but it is top notch stuff. (the PSI springs, Xceldyne retainers/locks/seats cost me around $900, though they do offer a lock/retainer setup that's a bit less money)

CalSpeedPerformance

iTrader: (64)

Hard part is the price of those springs covers the cost of going to titanium valves and a cheaper spring setup.

CalSpeedPerformance

iTrader: (64)

90% of the builds you see on here with big boost have 2.02x1.60 stainless valves in their heads... You rarely see guys stepping to Ti valves on most 1000rwhp Lsx builds due to the increased costs unless they have to due to valve weight.

WKMCD

iTrader: (2)

Take a look at the new PAC 1521's. I just out a set in my L92's to handle some serious lift on the new cam.

GIGAPUNK

iTrader: (2)

I'm running manley stainless LS7 myself. Richard at WCCH set me up with some 1.450" doubles

The spring pressures are as follows; Installed height = 1.855" Seat pressure = 163lbs Open pressure = 404lbs @.600"lift 426lbs@.650" lift. The max recommended lift for these springs is .660" and the open pressure will be approx. 430lbs.

They use his custom ti retainers and were less than $600 for the springs/retainers/machine work. He suggested that I not go over .630" total lift. But he also sent me some head/intake flow charts, and WITH THE STOCK INTAKE BOLTED ON there is a huge drop flow RIGHT at .630" lift. Weird. He also stated that these pressures were about the max you could use and still retain hydraulic lifters.

The motor won't be running till next year, but I'll let you know where I float!!!