bushing roller ifters

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Alan Roehrich
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Re: bushing roller ifters

Post by Alan Roehrich »

Schubeck's problem, was quality control more than anything, and the same applies to anyone else building lifters that way. To achieve really good reliability, the tolerance window is measured to four-five decimal places, minimum, and you have to be willing to throw away any piece that doesn't fit in that window, 100%. By far the greatest percentage of failures I've seen are where the lifter came apart because the puck was way too loose on the lifter body. After that, careless handling. Then failures related to use, such as severe valve float, and then, often the failure of another valvetrain part (pushrods going through the oil hole on stamped rockers was common).
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Re: bushing roller ifters

Post by Kevin Johnson »

kirkwoodken wrote:I would think ceramic rollers with cold stabilized Vasco Supreme axles are right around the corner. Liquid nitrogen quenched VASCO Supreme is 72 Rockwell but not brittle. Strong enough to send to the moon.
This might be an application for a dual drive camshaft where a second isolated drive at the front would link to the rear through a hollow cam core. I was thinking Tungsten Carbide but MadBill gently suggested the brittleness might be an issue.
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Re: bushing roller ifters

Post by cgarb »

There are many grades of carbide, Im sure there is one that would make it. If inserts will last cutting steel in a mill cutter I would think sliding along a lobe wouldnt be as much impact as cutting metal.
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Re: bushing roller ifters

Post by CamKing »

stokerboats wrote:
CamKing wrote:
panic wrote:The original 1929 Harley-Davidson roller tappet (18522-29?) had a bushing, only the later versions had needle rollers.
Yep, I'd say the Isky patent is about as usefull as the Patent on seatbelts.
I don't sell parts so my view isn't biased. I know many who swear by the Isky EZX lifter. Those who don't usually sell other stuff. :)
I'm not questioning the quality of their lifters. Just the inforcability of the patent. I have customers that swear by the Isky lifters, Crower's lifters, Morel's lifters, and my lifters.
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Re: bushing roller ifters

Post by CamKing »

kirkwoodken wrote:
CamKing wrote:You would need to find a ceramic material that can take a shock. That was the problem with the material Schubeck used. If you floated the valves, the stuff shattered into little "diamond hard" pieces that went thru-out the engine.
Sounds like a cam designers problem to me!
Nope. I can design a cam to be stable at any RPM the engine builder likes. What I can't do. is build/maintain every engine, and drive the vehicles. That's where the problems usually happen.
I learned long ago, no rev-limiter in the world will stop an engine from over-revving when the road race driver is trying to shift from 4th to 5th, and hits 3rd. The cam designer also has no control over the know-it-all that decides he needs the engine to come off the corner harder, so he loosens up the lash another .010".
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