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Rockers

This is a discussion on Rockers within the Internal Engine forums, part of the LSx Technical Help Section category; With a CheaTR cam can I use 1.8 ratio rackers? Should I use them? Do all cams(for the most part) ...

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    Member Phlash_riot's Avatar
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    Rockers

    With a CheaTR cam can I use 1.8 ratio rackers? Should I use them?


    Do all cams(for the most part) have the same Lobe lift?

    I know you take the lobe lift and multiply it by the ratio and get your make valve lift... What is the maximum lift taht you want on the vlave before you get yourself into the danger zone. This is for a 99 LS1.

    Also I saw a roller tipped rocker out there that open as fast as a 1.8 but end up only opening to a 1.7 ratio. That worth it?...rather is it worth the money?

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    The CheaTR cam has very fast ramp rates and the lift is pretty high from what I remember, I wouldn't personally go with the 1.8's myself on that cam. The amount of spring required to control it may be too much for stock lifters. Cams are defined by lift, duration, centerline angles and several other parameters, so the short answer to your question is "no" the lift on various cams will differ.

    If you would like to learn more about cam design, here is a good introduction:

    Cam Article by David Vizard

    He has also writen several books, one on cams and valve trains that has a lot of good information in it as well.

    Lastly, the rocker that opens faster is the Crane rocker, which is what I am running on my setup. The 1.7 rockers come off the seat at 1.79 and then the ration changes to 1.72 at full open. It is worth noting that even though a rocker ratio is called out as a specific value (for example 1.7), the ratio will actually change during the motion of the rocker, i.e., the ratio is not constant for any rocker even the stock rockers. The stock rockers come off the seat at 1.54 and then gradually change to approximately 1.69 when fully open.

    Hope this helps

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    member since may 2000 nhraformula's Avatar
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    no you cannot with the cheater cam unless you want to fly cut the pistons.
    2000 nhra edition formula
    a few bolt ons, 379 rwhp
    11.96 @113.25

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    Quote Originally Posted by nhraformula View Post
    fly cut the pistons.
    ?


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    do not use the rckers. period.- fly cut pistons believe he means deepening the valve notches in the pistons.

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    Quote Originally Posted by Hi-Po View Post
    do not use the rckers. period.- fly cut pistons believe he means deepening the valve notches in the pistons.
    Wich ones? 1.8 or the Crane ones?

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    Quote Originally Posted by vettenuts View Post
    The CheaTR cam has very fast ramp rates and the lift is pretty high from what I remember, I wouldn't personally go with the 1.8's myself on that cam. The amount of spring required to control it may be too much for stock lifters. Cams are defined by lift, duration, centerline angles and several other parameters, so the short answer to your question is "no" the lift on various cams will differ.

    If you would like to learn more about cam design, here is a good introduction:

    Cam Article by David Vizard

    He has also writen several books, one on cams and valve trains that has a lot of good information in it as well.

    Lastly, the rocker that opens faster is the Crane rocker, which is what I am running on my setup. The 1.7 rockers come off the seat at 1.79 and then the ration changes to 1.72 at full open. It is worth noting that even though a rocker ratio is called out as a specific value (for example 1.7), the ratio will actually change during the motion of the rocker, i.e., the ratio is not constant for any rocker even the stock rockers. The stock rockers come off the seat at 1.54 and then gradually change to approximately 1.69 when fully open.

    Hope this helps
    Thanks. Great article. Haven't finished reading it yet but i will get to it again tomorrow.. Great help... also not a help at all.. Answered ALOT of questions but as many as it has answered it has opened a few more up...*sigh. Well once i am done with the article hopefully i won't have as many.. You'll know I'll just post more questions in this thread. Thanks again

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    Quote Originally Posted by Phlash_riot View Post
    Wich ones? 1.8 or the Crane ones?
    1.8... the stockers are good for some high horsepower.

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    Yea I am going to go with roller tips so i am getting some just have to figure out wich ones to get though. I saw SLP made 1.85 but i dunno about those. Probably going to get Yella Terra 1.7s or the Crans 1.7/1.8(the ones that adjust as they go down)

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    The Yella Terra's were re-designed about a year ago to reduce weight (rotary inertia). Make sure you are looking at the new ones. The old ones are solid on top and the new ones have a groove on top to reduce weight.

    The Cranes are very good rockers, with barrel shaped bearings that will take more load. The 1.7's should work with that cam, just make sure you have good springs. That cam is very demanding on the valve train. Not sure you are aware of the spring maintenance required, but you will be changing them about every 15K miles with that cam.

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    member since may 2000 nhraformula's Avatar
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    the cheater cam has .600 lift.
    any higher rocker arm ratio can/will screw up youre pistons.

    rockers are fuckin useless anyways, i had a set before the cam, a whopping 9 rwhp.

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    Quote Originally Posted by nhraformula View Post
    the cheater cam has .600 lift.
    any higher rocker arm ratio can/will screw up youre pistons.

    rockers are fuckin useless anyways, i had a set before the cam, a whopping 9 rwhp.
    case and point. rockers are a waste of money.

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    Problem is you guys are one dimensional in your approach in that you only look at hp, did you check your wipe pattern with the stock rockers and the aftermarket cam setup? The wipe pattern on the stock rockers is wide and not necessarily centered front to back on the valve stem. Mine were all over the place when I checked them and decided to go to the full adjustable roller setup. The wipe pattern of the stock rockers may be OK with 70 lb valve springs (stock), but not so friendly to the valve guides when you start pumping up the valve spring forces and the lift.

    So I guess I don't agree they are as useless as you might think. Also, TFS is now recommending that the stock rockers not be used on their heads. Reason, wipe pattern is too wide which may lead to premature guide wear and thay "can" overhang the valve stem at the full open position. They are recommending the use of adjustable full roller rockers so the wipe pattern can be optimized.

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    member since may 2000 nhraformula's Avatar
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    Quote Originally Posted by vettenuts View Post
    Problem is you guys are one dimensional in your approach in that you only look at hp, did you check your wipe pattern with the stock rockers and the aftermarket cam setup? The wipe pattern on the stock rockers is wide and not necessarily centered front to back on the valve stem. Mine were all over the place when I checked them and decided to go to the full adjustable roller setup. The wipe pattern of the stock rockers may be OK with 70 lb valve springs (stock), but not so friendly to the valve guides when you start pumping up the valve spring forces and the lift.

    So I guess I don't agree they are as useless as you might think. Also, TFS is now recommending that the stock rockers not be used on their heads. Reason, wipe pattern is too wide which may lead to premature guide wear and thay "can" overhang the valve stem at the full open position. They are recommending the use of adjustable full roller rockers so the wipe pattern can be optimized.

    his question is plain and simple, can he use 1.8 rockers and the cheater cam, answer is no.

    now, what was worth more power in my set up, rockers or a cam? do tell me because you say we are one dimensional . the rockers arms were 1.85s and the cam is 581 lift. one of the above products had to go.

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    the cam lift was 581 with 1.7 or 1.85?
    If it was 1.7 then divide the 581 by 1.7 = 341.7
    So the 1.85 * 341.7 = 632
    So a 1.85 on that cam would be to high for a stcok sping and too high for the pistons assuming the stock pistons are flat faced...which i belive they are.

    NHRAFORMULA - Am I correct with these numbers and theories?

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    Quote Originally Posted by nhraformula View Post
    the cheater cam has .600 lift.
    any higher rocker arm ratio can/will screw up youre pistons.

    rockers are fuckin useless anyways, i had a set before the cam, a whopping 9 rwhp.
    Quote Originally Posted by Hi-Po View Post
    case and point. rockers are a waste of money.
    my vinci/crane 1.8 rockers netted me 17 rwhp. it's all about getting the right rockers. calling them a waste of money is how you perceive value.

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    Senior Member mrr23's Avatar
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    Quote Originally Posted by Phlash_riot View Post
    the cam lift was 581 with 1.7 or 1.85?
    If it was 1.7 then divide the 581 by 1.7 = 341.7
    So the 1.85 * 341.7 = 632
    So a 1.85 on that cam would be to high for a stcok sping and too high for the pistons assuming the stock pistons are flat faced...which i belive they are.

    NHRAFORMULA - Am I correct with these numbers and theories?
    .632 is getting up there in lift. but, it's not just lift that you have to be concerned with when it comes to piston to valve clearance. cam duration plays a big role. also, valve sizes. the opening and closing points have a bigger effect on whether or not the valve is going to hit the piston. when you are at max lift, the piston won't be anywhere near the valves. the piston will be close to bottom dead center.

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    Senior Member mrr23's Avatar
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    Quote Originally Posted by nhraformula View Post
    now, what was worth more power in my set up, rockers or a cam? do tell me because you say we are one dimensional . the rockers arms were 1.85s and the cam is 581 lift. one of the above products had to go.

    read my above post. did you ever actually check your piston to valve clearance before removing the rockers? or did you just go by your new max valve lift?

    i'll give you credit. at least you thought about the setup before just slapping it together and not check anything.

    and i agree with vettenuts. the problem with most internet mechanics when it comes to aftermarket rockers is they are one dimensional. the primary reason most people give when it comes to aftermarket rockers is they are a waste of money because of the low hp gains given with most of them on the market. almost no thought is given when it comes to strength, durability, and decreased wear on supporting components as vettenuts stated.

    and we could go into how the fastest cars are running stock rockers, yada, yada, yada.... i can bring up cars that are running 9s with the vinci/crane rockers as well.

    Quote Originally Posted by VHP website
    How’s that for a “compliment” from Popular Hot Rodding magazine in their August issue? In providing a brief overview of Grand Sport Racing (Rolex Sports Car Series of the 24 Hours of Daytona), Popular Hot Rodding reorted the banishment of Crane’s Gold Race Rockers from the track for being “just to fast,” according to the powers that be.

    On the first few practice runs the new GTOs (fielded by Flis Motor Sport’s Spirit of Daytona Racing) equipped with the new LS1 Gold Race Rockers with the “Quick-Lift® technology ran as fast as last season’s series-champion. And that was without any chassis tuning or tweaking! Well, they apparently knew that the rocker’s new geometry can add from 14 to 20 hp to the rear wheels and felt this was potentially unfair, so they banned the use of aftermarket rockers and mandated the use of stock rockers in the GTOs.

    We think Popular Hot Rodding summed it up pretty well when they commented; “It’s a rare opportunity for a company’s product to be banned and for them to actually be proud of it.” See the Crane Website for more information on Gold Race Rockers and pick up the August issue of Popular Hot Rodding for a great read.
    Last edited by mrr23; 11-02-2006 at 10:03 AM.

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    Quote Originally Posted by mrr23 View Post

    and we could go into how the fastest cars are running stock rockers, yada, yada, yada.... i can bring up cars that are running 9s with the vinci/crane rocekrs as well.
    well im glad you did. That why i say they are a waste, but to each his own.

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    Quote Originally Posted by nhraformula View Post
    his question is plain and simple, can he use 1.8 rockers and the cheater cam, answer is no.

    now, what was worth more power in my set up, rockers or a cam? do tell me because you say we are one dimensional . the rockers arms were 1.85s and the cam is 581 lift. one of the above products had to go.
    Don't disagree with the using a larger ratio on that particular cam, what I disagree with is that there is no utility in roller rockers vs. stock. There are distinct advantages, especially for a street driven car that has the potential to accumulate a lot of miles. I firmly believe that the valve guide wear can be minimized with the adjustable roller setup. That is my main point in "one dimensional", the reasoning is not all hp related.

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