RRhodes1

Hey all,

Just got off the phone with texas speed, and was recommended not to use yella terra ultralite 1.7's because of them potentially causing valve float @ high rpms.

anyones thoughts on this ?

Springs:
Patriot Dual Gold "Extreme" with Ti retainers, seats.

LS7 lifters

Heads stage 1.0 LS6 PRC's

T-rex cam

Max rpm: 7000

i bought the yella's for the rigidity, and i thought.. lighter weight....

Anyone?

vettenuts

iTrader: (4)

If I had to guess, it is likely because of the cam you are running and the upper RPM range you plan to take it. I run mine to 6,800 without issue. Actually, at that RPM I would think rod bolts might be the bigger question.

02*C5

iTrader: (1)

I am shifting at 6800 and red line at 7K with stock rockers. My cam has a .614 lift.

there is nothing lighter than the stock rockers period, and they are good up to a .650 lift.

What lift does your cam have?

RRhodes1

Its .610 / .615 int/exhst

rod bolts are being replaced before i spin it that high.

Goldfinger911

iTrader: (24)

Just to chime in.
I have the Yella Terra roller rockers that are the older style shown here: http://www.ls1howto.com/howto/geniii...t_vs_stock.jpg

I have milled 243's, a cam with .617 lift, patriot golds with Ti retainers, prelash set to .040", perfect wipe pattern on the valve, and I spin my 383 to 6800-7000 for the 2>3 shift with no float.

RRhodes1

gnarly.

the only reason im significantly concerned about valve float occuring is that this cam is stupid tight PTVC and im worried that if i get valve float it may just push it over the edge.

Goldfinger911

iTrader: (24)

Yeah I hear ya man. My PTC clearance is close but within requirements for expansion. I spent a lot of time measuring PTV and remeasuring PTV. I used a very accurate digital dial indicator and took my time.

02*C5

iTrader: (1)

Again I think that the stock rockers are the way to go. There are many proven engines making 600whp with stock rockers and have no issues. If there was one thing i would say is do the trunion upgrade and be done with them.

Good Luck.

JFM-jr

iTrader: (23)

I agree on a GM head the stock rocker arms are hard to beat. I have used them for the last 9 years on multiple 600+ lift cams without issue. The trunion uprade is a great idea. Valve spring forces and a quality pushrod/lifter combo also help insure your valvetrain remains stable at higher RPMS.

vettenuts

iTrader: (4)

If you are that concerned, you may want to spend the money on stiffer pushrods.

RRhodes1

I guess I should have been more specific with my setup.


It already has COMP thick wall hardened hi tech push rods LS7 lifters, patriot performance dual gold extreme springs with ti retainers.

02*C5

iTrader: (1)

Sell those LS7 lifters and contact Gaterman products and get a set of LS1/LS6 stock lifters. A lot of complaints from people causing failures here on the forums. Also do not do the CTS-V lifters either. I run set of new stock lifters in my set up with no issues $99.99.

RRhodes1

can i ask what your final PTV clearance was ?

whats typically deemed acceptable in LS engines?

JFM-jr

iTrader: (23)

Those are probably the run of the mill .080 wall hardened Comp pushrods. Better than stock for sure but will deflect under high load/RPM to some degree. Most dont have any issue but if the case is as you stated "stupid tight PTVC" then it's worth weighing a set of stronger pushrods. Those valvesprings have had a less than desirable reputation in the durability dept as well. Just my .02

vettenuts

iTrader: (4)

My point exactly

02*C5

iTrader: (1)

^^^X2 on the springs

I am using the Comp 921 and there are better springs out there. DO NOT SKIMP on your valve train.

RRhodes1

all good to know. what wall thickness will i be ideally looking for ( borderline solid push rod ? )

im entertaining flycutting for saftey's sake. The cam i have has an advertized .070" intake .090" ehaust PTVC. thats what i meant by "stupid tight PTVC" i will be checking it when the new heads go on. how tight is acceptable/safe.

the engine wont be seeing 7000 RPM very often.

shitty when you have already bought the yellas

im assuming i should just sell them then huh ?

GTO1_OHIO

iTrader: (3)

FWIW AFR warns that if you upgrade to roller rockers with their 205 head that the springs and lifters should be upgraded to avoid valve float. I'm putting in Morel lifters and PAC 1221 dual springs to support my new YT rockers. ... so if AFR has seen valve float with roller rockers on its 205s, I just have to think that stock heads or any lesser head would experience the same problem without the same upgrades.

vettenuts

iTrader: (4)

If you bought them, try them. As for the pushrod, the thickness doesn't get you much in way of stiffness, it is OD that counts. Bottom line, 11/32" from Terry Manton are supposed to fit stock heads.

JFM-jr

iTrader: (23)

Yes the 11/32 from Manton do fit I run them in my 5.3 GM heads and they are .120 wall thickness. Tremendous increase in strength over an .080 pushrod. Have you had the spring forces tested? Have you mic'd the spring pockets to evaluate installed height and hence determine if shimming would be needed? Personally i'd look into another set of springs. The PRC's from I have read seem to be a good bang for the buck (PACS are the top of the food chain) and even then you'd need to take the steps outlined above if you have'nt done them already.