I figured this thread would get more exposure here than in the GEN IV section and since spring choice isnt Gen specific its usefull to either gen.

Anyway I'm going for a max effort bolt on build with my setup in sig so keeping the stock ls3 cam. I have Yella Terra 1.85 ultralite rockers I will be running which is part no. yt6685.

Ls3 cam specs.
204/211 .551/.525 117

with the 1.85 conversion the lift should go to about .600 and .580.
My spring choices so far are as follows...

PSI-1511ML 130lbs @ 1.800in 370lbs @ 1.175in Coil Bind 1.10 384 Spring rate

Comp Conical 7228 spring 136lb @1.800" 412lb @1.170" 1.125" coil bind 438 spring rate

Duals (not decided on brand or specs)

This is not a "go with duals" because they have a safety net there thread. I understand that. I used to run 1511's in my old cam setup for 30k. I dont mind going with duals and I dont mind with going with a good single.

My main concern is that I want a spring that I can set and forget for a while and control the valvetrain. Naturally I will check them once a year but other than that I want a set it and forget it deal. My reservations for not going with a dual is that I have seen quite a few threads over the past year where springs were pulling off valve seals for seemingly no reason. Setup was right seals were fine etc it seemed like it was just happening and I never saw a definitive result of correction.

The conical design intrigues me. I know kcs has them and read his thread which is what got me interested in them. They seem to be a little stiffer than the psi springs which is good and only a little softer than a BTR or similar dual. The conical design is supposed to offer better harmonic control than either spring and still offer a good life span. But it does have a lower coil bind which I wasnt sure how shimming would play into. I also cant find any definitive proof the conical is a direct drop in for the stock head casting. Can someone answer that?

 

Weight of the YTs says you need probably 160 on the seat. If you can shim up a set of singles for that, go for it.

Otherwise, I'd do the PAC 1905s or BTR Max Pressure springs.

 

na on the stock cam you dont need much at all. I know the guys who run them on camaro 5 and the g8 boards all do it with a 1218. I dont want to flirt with disaster that much though since the g8 cam is a bit smaller. I think you only need that much pressure when youre running a decent cam to go with it lol. even so the platinums setup like so.

155 lbs @ 1.780", 380 lbs @ 1.180", 400 lbs @ 1.130,

i actually think they'd be a pretty good fit especially if i shimmed them a bit. no?

i sort of want the insurance with a dual spring but i think the smooth profile of the stock cam would be more than fine with a good beehive.

btw what do people use for a micrometer on dual springs? I really dont want to fork over 120 bucks for the pac one since im only going to use it this once. i was hoping someone would say the summit one for 39.99 was good

 

I guess. Then just run the regular BTR platinums or 1511s.

 

btr specs are pretty close to what you said anyway though 155 on the seat and 380 open is where i would be with the .600 lift. if i shimmed it down i could push the seat pressue over 170 if i shimmed it to .06 of Coil bind with ease i would think

 

I don't believe KCS has fired the engine of his with the conical springs, however he did say that he was not pleased with the GM retainer fit inside the top of the spring.....IIRC he felt it was too loose but decided that the added harmonic stability should keep it from moving around too much.
In your situation I'd go PSI for a beehive shimmed down .030" for a bit more seat with those rockers or else the Lunati dual kit would work well also.

 

Thanks guys so let me bring this into the equation now as well. I'm on the fence about about pushrod size I have a set of 5/16 companies pushrods that will probably work but I'll have to measure it all out.

Should I spend the coin and go with a 11/32 one instead? If this was a cam setup it's a no brainer but it's not lol. And my concern was also that even though it's on the slower side of the valve the heavier pushrod might cause control issues with the beehive

 

Why the support for the beehive over the dual on this one? Seems like everyone's hopping on the dual train these days I'm ok with either so just wondering

 

Dan, how high you plan on spinning your set up? After reading that thread on dual vs single and hearing stories at New Era I'll never consider a single spring. Just my .02.

 

well the stock ls3 cam peaks at 5900-6k and falls off by 6500 so I'll be shifting right around 6400 which is pretty much where i shift it now.

I've never had an issue with psi nor have I ever even heard of one but its a heavy chance to take i realize. only thing that sucks is buying a really expensive micrometer for the duals from pac to measure the installed height lol

 

PSIs have zero failures.
You have hollow valves right ???
Mild lobe intensity on the factory cam.
I'd go 5/16" .080" push rods as more than fine....I assume you'll be all done by 66-6700 rpms anyways.
The only real control issue is the heavier rocker arms and the increased ratio adding some lobe intensity/valve speed.
A vernier caliper can also substitute for your height mic.....FYI

 

Ya I had psi 1511's on my old cam setup and they were flawless even with 25k on them they pulled clean on the dyno to 6800 rpm. Probably shift this around 6400 since the ls3 cam is really done at 6500 and falls off hard from there. Would I shim the intake and exhaust to .07 of CB or shoudl I just shim for the intake side since that has the most live

I have never used a caliper to measure installed height before. It should be possible with the heads on the car correct? Any quick how to's on that? It would be awesome to save 100 bucks on a tool i'd use for 20 minutes.


Oh and ya the ls3 valves are 88g on the intake and 89g on the exhaust.

 

IIRC the PSI springs are a .630" max lift when installed at the factory 1.780" height. Since you only need 600 capability this gives you a bit of seat increase to help with the nose heavy rocker arms
The dial caliper (generic height mic) really is an eyeball sort of procedure, figuring 010" or so either way will be just fine
On Gen I engines the retainer is larger diameter and helps with keeping the calipers vertical. On LS the seal/spring perch or shoulder is a larger diameter than the retainer so try to resist leaning the caliper over
You can also take a piece of cardboard and put incremental marks on it to stand down in there with the retainer and locks in place since the engine is in the car adding visual difficulty....lol
Another complicating issue is getting shims if needed under the factory seals
Perhaps check the Manley catalogue online to see if they offer minus .030" or minus .050" locks and consider picking up their Ti retainers just to shave a few more grams of weight at the valve if you can afford it
IMO the added lift, low friction rockers, stiffer pushrods, Ti retainers, and properly set up springs would allow a 6600 shift point which always pays dividends on shift recovery after the drop

 

Ok so if the springs install at 1.78 and the lift is .600 then that leaves me at 1.18 at max lift if I shim it .03 then I get down to 1.15 which is .05 from cb. So in essence what should I shoot for interms of height from cb? I know that if for some reason the springs install at 1.75 i couldnt even really use a shim because it puts me too close to cb. So i assume i just have to measure and see what puts me in the range I need to be? I see anywhere from .05-.07 is desired?


and that is true i forgot that shims would need to go under the factory seals. in that case could i just order the seals and seats used in dual spring kits?

 

doing some research this morning and its really hard to beat the BTR kit lol just from a finance standpoint.

PSI 1511 Kit $200
Seals $20 (needed for shims)
Locators $30 (needed for shims)
__________________________
$250 with stock retainers

BTR kit $299 with TI retainers, I realize they are a little heavier but will offer the same spring rate and have more seat pressure. And it s acomplete kit ready to drop in. I coudl even shim them a bit if needed.
http://www.briantooleyracing.com/660...ers-sk001.html

 

It is a factory cam. These engines came from the factory with single springs that will last well over 100,000 miles. There is nothing wrong with a single spring in the correct application.

The PSI springs should be more than adequate. Personally, I would measure pushrod length and get a set of Trend 3/8" pushrods for added stability.

 

3/8 barely fit in stock ls3 castings and with the yella terras theres no way they're going to work without head work. i'm going to measure anyway but there is a VERY good chance the ones i already have will work. but if not i'll just sell them and go from there

Heres the thing I'm not against a beehive at all except in a violent cam situation each one has their place. Its just in this case if im going to shim the psi spring i'll have to go with new seals and locators in which case the btr kit is almost the same price and offers that extra security so its really a toss up.

 

If you had a cam in the car I would say get btr platinums or if you think you will cam the car down the road then get the btr plats now.

 

The Trends clear my factory castings without any issue.

Granted, I don't have Yella Terras, but I have plenty of clearance with the Trends. I even have a set of Trends in a 5.3 with 862 castings with factory rockers and plenty of clearance.

 

In that case I may order one to just check are they 3/8 the whole way or tapered. Besides the 862 what other heads they in

And no plans for a cam if anything I'll put a blower in it which then it would be nice to have the platinums anyway. I just have a hard time doing the beehive since the btr is almost the same price. I'm not against a beehive at all especially psi but it's the same cost...and they have the same spring rate so the hp difference will be 0