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With several brands of full roller rockers out now, I have noticed that several people are going to 1.7's with their "big cams"(IS3, XPZ). I am thinking that obviously this extra lift is to essentially further increase the high rpm power potential of their current setup. Is this safe to do on 130 pound valve springs? Would you be in danger of valve float at high rpms? Or are people using even higher spring rates that I don't know about? Also, it is my understanding that the BadSSEI is using the stage 4 blower cam with 1.7's. The theoretical lift there is HUGE! I guess my question is are the 130's working just fine in these "extreme applications" or are they being pushed to the point of floating or some other adverse side effect. What is going on in these extremely high lift valvetrains?

Thanks in advance...
 

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Discussion Starter · #2 ·
I see now that there are 150# valvesprings mentioned on the Intense site. But still, how would/do the 130's work? I believe that there are still people using them.
 

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I will be adding 1.7's on top of my stage 3 cam, Chris Yates and Tim King have done the same. It is perfectly safe to run this on the 130 springs, no problems thus far. BadSSEi does not have 1.7s to my knowledge.
 

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Our ten second Bonneville SSEi is currently running the Stage 4 Blower cam, with 1.60:1 full roller rockers, and 150 pound valvesprings.

130's should be good for the Stage 3 grinds with 1.60:1 or 1.70:1 rockers.
 

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What about piston to valve clearence? I want to put 1.9s on my exhausts only...I have a TEPcam and 130# springs.

I wish your varible duration S3 cams were around before I went with the TEP single patteren type..

Any thoughts?
 

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What about piston to valve clearence?
You'll need to measure your combination, but we've seen enough clearance for more than .750" of valve lift in some of our race engines.

<<I want to put 1.9s on my exhausts only...I have a TEPcam and 130# springs.>>

I don't think you'll be able to find valvesprings to accept much more than ~.625" of valve lift, and that would be ~.673".
 

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The downside of big springs (beyond what is needed) is accelerated valvetrain wear and chain tention...
Something to keep in mind if its a daily driver that you want to be built to last.
 

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Kind of off topic but not completely, it seems like quite a few people are running the 130 lb springs, I was wondering what the mileage expectancy is for them when run mostly on the street (with the double roller chain to lessen the chance of damage there). Do you think it would be okay for say 50,000 miles before things would need replacement?
 

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Howdy,


It is my personal opinion that these "big" cams tax a 130# spring even with 1.6 rockers. I can't approximate a lifespan, however, I would have springs checked at least before every race season. With 1.7's all bets are off!


BIG JEFF
 

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Discussion Starter · #10 ·
BIG JEFF said:
Howdy,


It is my personal opinion that these "big" cams tax a 130# spring even with 1.6 rockers. I can't approximate a lifespan, however, I would have springs checked at least before every race season. With 1.7's all bets are off!


BIG JEFF
So its more of a question of spring life? Would they float or cause problems even if they are still in good condition? "Taxing them" as far as shortening the life is a given in racing, but it would seem to me that valve float should be avoided at all costs IMHO. Am I correct in my thinking?
 

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ChrisF said:
So its more of a question of spring life? Would they float or cause problems even if they are still in good condition? "Taxing them" as far as shortening the life is a given in racing, but it would seem to me that valve float should be avoided at all costs IMHO. Am I correct in my thinking?


It goes without saying that life would be shorter with a higher ratio rocker. Worn springs will float valves, which is bad enough. Worn springs break as well, which can be catastrophic. I know lots of racers that check seat pressure
after 50 passes or so.
I am not trying to scare the crap out of you, I am trying to make you understand that with cams that big, springs wear much faster than a stock setup. I think that alot of people are assuming that 130 # springs have the longevity of a stock setup. Several companies like Moroso ake a seat pressure tester. You can use them not necessarily to measure seat pressure, but to see if a spring is noticeably weaker than others. This advance notice can prevent major engine damage.


BIG JEFF
 
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