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Old 11-17-2011, 07:19 PM   #31
eb02z06
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Default Re: Valve Float

Is there a lighter roller rocker than the YT Ultra lites?
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Old 11-17-2011, 11:24 PM   #32
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Default Re: Valve Float

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Originally Posted by eb02z06 View Post
Is there a lighter roller rocker than the YT Ultra lites?
Yes but run them any way.
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Old 11-18-2011, 12:11 PM   #33
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Default Re: Valve Float

I had the same exact problem you do but using comp pro mag rockers on my n/a LS1 motor a couple years ago. I had a similar cam to you 230/240. The car would pull hard to 6400 then just laid over/felt like valve float absolutely would not turn anymore rpm's. Long story short a guy from thunder racing chimed in said that these aftermarket rockers pro mags, yellow terra's ect work great in some applications - not turning high rpm's, small cams .550 lift or less cams. Anything else the tip of these rockers are too heavy and excessive acceleration/deceleration of the valves they will float.
I threw a set of stock rockers back on my car the problem was gone.
Heres my post on tech about it and the guys response.

http://ls1tech.com/forums/generation...-6450-rpm.html


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Originally Posted by XtraCajunSS View Post
The rockers are actually a very good design and work well in other applications with lower ratios and much milder cam lobe families. I've used Comp Pro-Magnum rockers for years with great success in SBC, LT1, and SPF applications with no problems. Most of these engines only rev to 6K or so and are running a max of 1.6 ratio with .550" lift cams or less. I also use 7/16" studs for these apps.

The problem with the LSx version is two fold. First of all, the weight of the rocker tip over the valve. With most current LSx cam lobe designs and the extensive use of higher rocker ratios, you end up with excessive acceleration/deceleration of the valve which causes valve bounce or "float".

The second issue has to do with the 8mm rocker stud which is basically 5/16". This is not a very stable platform for the rocker to work off of and also contributes to instability in the valvetrain.

These are the 2 primary factors along with engine speeds commonly in excess of 6500 rpm which contribute to a power robbing, parts destroying situation. This is a primary cause of valve spring and lifter failure and can also cause piston to valve contact if the valve bounce is great enough.

IMHO, there are very few options better than a stock rocker with trunion upgrade. I know some folks are having success with the Yella Terra ultra lights but even in this case, you had better know what you are doing when setting them up. That's why my most common reccomendation is to run stock rockers. I've had hydraulic cam stock headed cars turn 8200 rpm with stock rockers. GM really did their homework with this design.

Thanks,
Shane

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Old 11-18-2011, 12:26 PM   #34
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Default Re: Valve Float

The selection of springs now is vastly greater than 2 years ago. So while the rockers are the issue now, there are springs out there to resolve the issue too. Either route will work. With the low spring pressure you have now though I would opt for the springs honestly. Just my $.02
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Old 11-18-2011, 11:53 PM   #35
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Default Re: Valve Float

I'm running the yella terra's I had on my TFS235's in my other car (Formula) which is a cam only '02 LS1 and I'm running Patriot Extreme's on it with standard Trickflow 7.400" pushrods and the stock lifters and I have spun it up to ~68-6900rpm on the dyno with no float at all. The springs are only rated for around what you measured on yours as well. I'm going to pull them off on the dyno one day and swap the stockers back on there to see how it reacts in the upper RPM to see if there is a difference.

However I'm sure that once these springs start getting some miles on them that the yella terra's will cause issues. The only reason I've not put the stockers back on yet is the cam is a LSL cam and has 621/624 lift and I know the stockers start to scrub above ~.580 lift and I had these sitting on the shelf so why not use them....

Be nice if someone would make an aftermarket LS1 1.7 rocker with a similar scroll as the LS7 lifters so that the rocker wont be opening the valve with the very tip end of the rocker like stock.
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Old 11-19-2011, 11:30 AM   #36
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Default Re: Valve Float

The springs that all TFS heads come with are generally about 160 seat and about 400+ lbs @ .600" lift and 450 lbs @ .650" lift. It amazes me with the thousands of sets of these in circulation that some of these "gurus' don't know what comes standard on these heads.

If you've killed that much pressure from those springs then I think your lobes are way too aggressive.

If you're running XER lobes or something similar I would switch over to something smooth like the HUC lobes or something equally smooth.

If it's a track only car then ditch the roller rockers and run stock rockers.

What are your cam specs? Manufacturer?
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Old 11-19-2011, 11:37 AM   #37
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Default Re: Valve Float

And the correct spring part number is TFS-30600415, it is a dual spring that is also sold under AFR as their 8019 upgrade spring for an extra $100 last I checked.

I don't understand how it is manufacturers can't seem to provide the correct picture with their parts, so don't pay attention to the picture, it isn't correct. http://www.trickflow.com/partdetail....5&autoview=sku

The TFS-30600414 is the same as the Patriot Gold springs.

Also, this year TFS switched from Associated to Peterson (PAC) for the standard springs, either are very nice quality springs.
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Last edited by Brian Tooley; 11-19-2011 at 11:40 AM.
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Old 11-19-2011, 11:49 AM   #38
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Default Re: Valve Float

One last thing, did you buy the heads new? What do the springs look like? Meaning are they normal spring color? Or is the outer shiny and the inner gold colored?

I ask this because I've seen guys remove the TFS springs in favor of Patriot Extreme springs, @ .650" lift the TFS check 450 lbs on my spring checker and the Patriot Extreme check 370, so something else to think about...
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Old 11-19-2011, 12:30 PM   #39
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Default Re: Valve Float

Maybe this will help also, pictured left to right, AFR 8019, old TFS Associated spring, new TFS Peterson spring, and a spring made for stock rockers (less open pressure)
You will notice that either "standard" spring has a taller inner spring than outer. Hope this helps.
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Old 11-19-2011, 02:00 PM   #40
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Default Re: Valve Float

They were new in the box heads. I have a set of the patriot Extreme springs that I can put on if they will work. I have one more race before I pull motor to freshen it up would like to find the prob first.
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Old 11-19-2011, 02:12 PM   #41
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Default Re: Valve Float

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Originally Posted by neals89GT View Post
They were new in the box heads. I have a set of the patriot Extreme springs that I can put on if they will work. I have one more race before I pull motor to freshen it up would like to find the prob first.
You need to test the Patriot springs against your springs, test several of your springs.

Make sure you test them with the retainer sitting on top of them. The distance from the top of the retainer to the top of the outer spring is about .120" so you can figure that in when checking. For example, with the retainer in place check the springs at 1.920" which will be 1.800" height for the springs. I hope that makes sense. I see people check springs without the retainer in place, that's ignorant.

I would be shocked if a new set of Patriot springs had as much or more pressure than your used TFS springs, as I've never seen a set of TFS springs lose that much pressure.
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Old 11-19-2011, 02:47 PM   #42
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Default Re: Valve Float

Only thing I can really note is that the heavier rockers work the springs harder, shortening there useful life span.
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Old 11-19-2011, 02:51 PM   #43
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Default Re: Valve Float

I would have to buy the patriot springs to check them.

So what would be the first thing I need to do.
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Old 11-19-2011, 03:15 PM   #44
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Default Re: Valve Float

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I would have to buy the patriot springs to check them.

So what would be the first thing I need to do.
Did they test your springs with the retainer in place?

When did you buy the heads? How old are they?

I have a brand new set of the new TFS PAC springs that will drop right in for $120 shipped. These checked 430 lbs at .600" lift and 460 lbs at .650", if you float these you have serious issues with your cam ramp speed.

You'll be hard pressed to find anything better for less than $300, and that's just the cost of the springs, not counting retainers or cups.

You never did say who made your cam and what the specs were?
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Old 11-19-2011, 03:57 PM   #45
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Default Re: Valve Float

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Originally Posted by Collinsautomotive View Post
Only thing I can really note is that the heavier rockers work the springs harder, shortening there useful life span.
Yep which is why I'm going to put mine on the dyno next week and do a little comparing of the two. I have brand new patriot extremes on the car right now so it should give a good idea of comparison between the rockers back to back on the dyno.

With that said when these come off anybody wanna buy some YT rockers? lol I would consider trades to some stockers with the comp trunion upgrade as well or even some of the SLP 1.8 rockers. I want a set of them to check out and just do some bench testing on.
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