Lifters / Valvetrain - not just Hyd VS Solid
- Thread starter Route666
- Start date
-
Sponsors (?)
I can't make a personal recomendation on this theory, but a local Stanger swears by this. He bought a sinlge pattern cam based on advice form his engine builder (must have been wearing a bowtie if you ask me) and found he was restricted on the exhaust side. So he replaced every other 1.6 rocker with a 1.7 and fudged a dual pattern cam somewhat. I really did wake up his ride too, that part I can attest to.
Single pattern cams are useful with stock small block heads, but the aftermarket heads don't have the restriction in the exhaust ports the factory heads have and thus don't really need the extra lift or duration there.Edbert said:
The single pattern Z303 cam I'm running works fine with the Canfield heads on my 331. 
Plus the real reason for chooosing it was the price----- $110 shipped and it was brand new. 
SoCalCruising said:
That's true, but I've read good argument not exactly that is pro beehive, but that makes duals just as bad. For example: Even though springs could break at any rpm, most likely it would be when being pushed, and if one breaks on a dual setup, the spring that's left most likely won't have enough in it to control the valve, (otherwise why have the other spring?) and it'll still smash into the piston.
Plus single springs have been run in cars for aeons, even older performance cars. Sure not the performance of today, but other things have improved also to alleviate stresses, rollers, better oiling, better manufacturing, better compounds and alloys, etc, etc.
I guess that's where my confidence in them as an engineered solution comes - They are designed to eliminate natural resonance - the reason that platoons (or whatever the group is called) break step over bridges to stop them breaking, they also reduce their own mass moved by the way their built, and thus also the retain mass, so the spring tension required to control themselves and the valve and retainer is reduced, meaning that there is less internal stresses in the spring. I guess it's closer to a resting state - like a smaller car requires less torque to accelerate the same as a larger car. They both have the same exterior performance, but the internal stresses are less in the lighter car.
Anyways, I understand what you're saying, and that is something that is a negative in my mind, just not as much as it seems others see it.
EDIT: I also don't wait to build strictly for high rpms, so the cam should have less duration - and that in turn usually means easier ramps, and I don't want huge lift, although huge lift doesn't hurt torque or power right?
What do you call huge lift? is .55 considered overly big? (That is bigger than I've considered, I've always compromised down in lift for valvetrain safety / reliability when dreaming / thinking.)
D.Hearne said:
But wouldn't adding extra control to the valvetrain at high rpm inherently increase the rpm potential?
But the rpm potential of the valvetrain is still increased right? I don't mean the motor, I mean just the valvetrain.
Depends if the rockers can handle the extra load - i.e. The reduction in spring load may need to be offset by stronger valve train components (pushrod, rocker stud, rocker itself). If you don't then you might end up with a spectacular failure (broken rod/rocker) rather than just valve float.
Better springs will help stabilize the valvetrain, yes. But it is not all that simple, there are many components that ALL need to be looked at and matched, upgrading one and not the others will not get the results you expect.
But in general terms anything you do to stabilize and increase the precision of the valve-events will allow for more RPMs.
But in general terms anything you do to stabilize and increase the precision of the valve-events will allow for more RPMs.
Yeh basically how I saw what D.Hearne said was, for example: valves floating at 6700 - rev kit stabilises valvetrain at 6700, no longer floats there, valves now float at 6900 - increase in rpm. Ok maybe not, maybe another component isn't up to it, but in general nothing's likely to be on the limit anyway.
COVER, I see the point you're trying to make, but it doesn't seem sensible to me that a reduction in spring pressure is going to require stronger components elsewhere, quite the opposite in fact. I do concede however that with a rev kit there will be more pressure on the lifter's rollers and the cam lobes, so perhaps that area would be unable to survive due to increased strain.
COVER, I see the point you're trying to make, but it doesn't seem sensible to me that a reduction in spring pressure is going to require stronger components elsewhere, quite the opposite in fact. I do concede however that with a rev kit there will be more pressure on the lifter's rollers and the cam lobes, so perhaps that area would be unable to survive due to increased strain.
Maybe I didn't say it right or got the purpose of the rev kit wrong, but.... I think it's also to keep things in place when a valve drops also, to avoid other damage. Like the lifter jumping out of the hole, etc. Anyway, rev kits are meant to be used in race motors, 99.99% of street motors don't need it.
It sounded like you were saying they're for the ultra extreme the first time, but the readily available net shops selling them made it seem a little more common.
Oh while we're on the subject of extreme valvetrain thinking - what about roller cam bearings - like actual roller bearings for your cam. I've seen it a couple of times on the net, seems very rare to find any info on it. Are they the same? - ultra extreme?
Oh while we're on the subject of extreme valvetrain thinking - what about roller cam bearings - like actual roller bearings for your cam. I've seen it a couple of times on the net, seems very rare to find any info on it. Are they the same? - ultra extreme?
Yea, I asked this question to my race motor builder friend, his take on them is they tend to transmit cam vibrations to the block more so than friction bearings. Same as gear drives transmit crank harmonics to the cam. He doesn't feel their benefits outweight the cost( boring the block to fit them) and drawback.Route666 said:
brianj5600
Active Member
I think roller cam bearings are more for cam that need HUGE springs. I've heard of big springs killing cam bearings if the motor sits too long, no oil around the cam. A friend of mine had that problem, now if it sits more that a couple weeks, he primes the system.
Yeh I wasn't too fascinated by them, but they looked interesting. I had an idea of getting a couple of tapered roller bearings and machining the block and thrust plate and the cam, and using one at either end. I know you can get thrush bearings for the camshaft though, so it's kind of a redundant idea.
65ShelbyClone
Founding Member
I saw the roller cam bearings(and lifters) in a 427FE that Mustang & Fords was building. They were using stock bottom end parts and ventilated the block on a dyno run.
What would be really cool is needle bearings for the rods and or/mains. It would be like a single or twin cylinder bike engine.
What would be really cool is needle bearings for the rods and or/mains. It would be like a single or twin cylinder bike engine.
Do bikes have needle bearing mains?
I don't know how that works, especially on bikes, 14krpm redlines and such. I mean the needles probably have less that 1/20th the circumference of the crank journal, so they're going to spin 20 times faster - that's what, 280 000rpm lol man that'd buzz. But if it works, it works.
I don't know how that works, especially on bikes, 14krpm redlines and such. I mean the needles probably have less that 1/20th the circumference of the crank journal, so they're going to spin 20 times faster - that's what, 280 000rpm lol man that'd buzz. But if it works, it works.
brianj5600
Active Member
Only on 2 strokes. Needle bearings require one piece rods and press together cranks. Can you imagine indexing 4 rod journals? I wonder what it takes to run 1.75 rod journals as in NASCAR? That is their answer to friction. Lighter crank, less bearing speed, lighter rod, what's not to like? I forgot the main size, but I think it was reduced too.D.Hearne said:
Similar threads
