I have a 212/206, 111 deg split austentemper (COMP??) cam. I'm going to use Kmotion 750 springs at a max of ~ .523" lift. The max lift spring load is somewhere around 400lbs. Does someone know for sure what this cam can manage as a maximum shear force?
Austentemper Cam Max Shear Force
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wantattype2
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I also have the austentemper Comp Cam and when I ordered my Champion ported Iron Heads set up for a roller cam, I believe the 750 K motion spring came on them . My cam only has 510 lift. with stock rocker arms. I hope this helps.
turbobitt
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It is probably to hard for most of us to quantify. I'm sure a stress analysis can come up with some opinion. One must remember that for each lobe working against a spring there is probably another assisting in some capacity . One thing to note is that with only 12 lobes the load reversion pulses on each cycle will be more aggressive than a 16 lobe cam and is probably more detrimental to the timing chain.
AG.
fastblackracing
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Do you know what your installed height is for sure? You may be closer to 360-375 open pressure, the max pressure stated by the spring company is at .080 thou more cam lift than what you have. IMO you will be fine, the early 20 years ago experience with some of the first cast roller cams I had we experienced chipping of the nose area of the cam due to valve lofting from not enough open pressure. You still need to control the lifter no matter what the cam core is.
I'm using worst case install height (1.75") @ 140 psi. My Max Lift load @ 1.20" (0.523") is ~ 400 psi based on the spring data. Coil bind is at 1.115" and max lift is 0.550.
I agree with you that the timing chain gets pulled back and forth by 1/6 of the total possible reversion force rather than 1/8 of the total reversion force. I was looking at the idea of a simple beam calculation (summing an example force) along with the cam material properties / characteristics may yield a max number less case hardening & magic dust.
fastblackracing
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k motion web says 130@ 1.700, 395@ 1.150, coil bind at 1.050. 482# per inch rate. If you install @ 1.750 you may not have enough seat pressure. I bought an LSM spring tester a few years ago so I could know exactly for sure what my pressures are. Its expensive but I justified it by considering it like another go-fast part. Its good to know exactly what you have, I would not run less than 130 on the seat, 140 would be better.
Actually the data I have is close. As a compare look a the PAC 1201 data. They shift there install & end open heights 0.050" to look better than the competition. Based on Max spring pressure at lift for my configuration I'm going billet. I'm below max lift (0.550") at 0.523" . Open load (437 psi) at 0.550" lift is too close to the cam max spring load. There is very little safety factor even if your specific cam is on the high end of manufacturing capability.
BEATAV8
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I've been running the PAC1201's at 410lb - 430lb open for a while now without any apparent cam distress. Cam is an "off the shelf" 215/220 from FTS. It's actually been ~3yrs now with that setup. Comp 853 lifters too.
Just had it all apart and everything looking fine.
Just had it all apart and everything looking fine.
How do you like that FTS cam. I also wonder what your rocker ratio is?
BEATAV8
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The cam is fine for my combo, not too aggressive. Running 1.55 ratio scorpion rockers.
Mike Licht
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the newer (last couple years) austemper cams with have no problem at that pressure. They are now grinding some solid profiles on those style blanks. I run about 450 open on mine
Mike
Mike
Mike I have lost confidence in my "austentemper" scenario since I was given an "internal" (from the supplier) spring pressure "max" of 455 psi. Then I was told that the supplier likes to see usage of this material under 500 psi. This could imply (with a 5% manufacturing variation in process) depending on how "average" my cam is, that my toes could be over the cliff. I'm looking billet since max pressure exceeds what I need to have. Also there is a lot to be said about valve springs as well, but that is for another time.
Mike Licht
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In the past two years I have seen FAR more problems with billets. Some digging into block, lobe failures, cam sensor gears not lining up due to the hardware differences. (any blame the front cover) If I dont need it I am not using it and I have a 1201X spring in at 1.750 with .565 lift. which is well over 400PSI open. I respect your opinion but my experiences have been different.
Mike
Mike
I have seen many problems over the years with cam installs. Sadly it was the installer/assemblers fault almost every time. I do remember having to sink an ausrempered roller deeper one time which was easily accomplished by machining the thrust surface. I have seen more valvetrain issues because of inadequate/improperly setup springs and wrong pre-load/wrong length pushrods than just about all other mechanical engine faults by shade tree mechanics combined. Not everyone is qualified to install a cam. Not measuring will get you in a shit hole of a mess most often
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Couldn't be said much better
