SStressin

iTrader: (5)

I always thought for them you want less spring pressure becuase it will take the stress off them and have less of a chance to break them. I know i have new design so i probably dont need to worry about it. But whats your opinions on it? The rest of my valvetrain is a .650 lift eps lobed cam, tfs cnc 225 heads with the valves they come with, prc .675 springs with titanium retainers, btr slr lifters, and 3/8 pushrods.

I was going to sell my prcs to get btr .660 platinums to lower spring pressure to help out the yella terras but heard different in another post. Im also going to spray the car so i believe id need more spring pressure with adding boost idk if thats the same with spray.

JakeFusion

iTrader: (7)

PRCs would be fine. The 483lbs/in spring rate is perfect for the YTs. I think you need in excess of 460 to really control the YTs. But having more seat pressure might be ideal. So shimming them might work really well for you.

And if you wanted to swap to BTR springs, the .650" Max Pressure springs are what Tooley sells for YTs. They have a ~460lbs/in spring rate and a 150lbs closed pressure. So slightly less agressive than the PRCs but about the same closed pressure.

Tooley also sells the PAC 1208X... bit more lift headroom, but same spring rate as the BTR Max Pressure ~ 460lbs/in, but 160 on the seat.

I wouldn't switch tho. The PRC EHTs give you headroom on your .650" cam and have enough rate for the YTs. If you have issues, shim them up to get the closed pressure up over 170.

dr_whigham

iTrader: (49)

You'd want to shim for coil bind to begin with. What I've always read and heard, is that yes, you want MORE spring pressure to control them, but even YT doesn't like you to go over 400#. I didn't think they'd warranty them if they knew you were over 400. Maybe I'm wrong...

Edit- the max they recommend is 425 open.

JakeFusion

iTrader: (7)

That was always the question. How much can they take? 450? 500? 400? I've heard they can take 500 with the Gen 3 design. The PRCs are pushing it. Especially shimmed.

dr_whigham

iTrader: (49)

Just found it. The max they recommend is 425 open.

That's for the ultralites.

The Platinum series is rated for 1000#, which a lot of people don't even know about...

SStressin

iTrader: (5)

Yea i know i ways heard dont go over 400 with the yella terras. Now i hear go over it to control them so i have no idea to keep mine or sell the for btr springs. Im just trying to get my valvetrain perfect for when my motor is back together next month. Dont want these new rockers to break

dr_whigham

iTrader: (49)

It's a gamble either way.

I can tell you that Scorpion has DRASTICALLY redesigned their LS1 line since their big snafoo... What was it? 2010 or whenever they were breaking like candy canes.

Good thing about them is they are made in the USA, and always answer the phone.

TurboBuick6

iTrader: (2)

Jake mentioned the PAC-1208X's, that is honestly what I would recomend as well. I would also highly recomend a better than stock lifter as well.

SStressin

iTrader: (5)

I already ordered the new yella terras and i deff dont wanna sell and re buy rockers. I had the gen 2 on my prc .675s and they never broke. Actually were perfect. Il end up selling my prcs and get the max pressure btr so atleast i lower the pressure a tad bit on them

JakeFusion

iTrader: (7)

That's what I don't love about the aluminum roller rockers. They still are heavy MOI-wise, but aren't that strong.

Are the Platinums steel bodied?

miami993c297

iTrader: (6)

If someone is asking YT USA the answer will lead to the correct springs for the LS:

VHP HD SK
#150 close at 1.800
#420 open at 1.150
Good for 0.660"

I am revving those to 7400 rpm with the Gen III YT Ultralites.
The lift of my camshaft being in the 0.624", you can guess I shimmed them!!!
Christian

JakeFusion

iTrader: (7)

Those are Vinci?

Looks decent.

SStressin

iTrader: (5)

What springs are those?? Can you send me a link. Looks pretty perfect for my build my cam is .647 lift so i think tbag works perfect witb me

SStressin

iTrader: (5)

If i shim them and get the pressure up that will be even better! Found those springs by the way. Deff think i am going with those especially since they are designed and worked with yella terra to design them

miami993c297

iTrader: (6)

Yes, Roger Vinci.

Christian

GrannySShifting

iTrader: (10)

I like how Vinci touted the Crane stuff as being the best rocker on the market leaps and bounds ahead of everyone else... now he is a big YT importer?

JakeFusion

iTrader: (7)

Well Crane did go out of business, sort-of, so maybe he needed a new supplier?