Hyd roller camshaft question
11-07-2005, 06:16 AM
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Hyd roller camshaft question
Ok heres the deal I got a 96 vortec block with powder metal rods
windage tray the works. I want to run a 540 lift camshaft but I have read that the lifter bottoms against the little plates the
spyder holds down if you go over 520 lift. Anyone went over
520 lift with the stock hyd roller set-up? Any help would be greatly
appreciated.
The rest of the motor will be 2304 pistons and alum heads so yes I really need that much cam.
windage tray the works. I want to run a 540 lift camshaft but I have read that the lifter bottoms against the little plates the
spyder holds down if you go over 520 lift. Anyone went over
520 lift with the stock hyd roller set-up? Any help would be greatly
appreciated.
The rest of the motor will be 2304 pistons and alum heads so yes I really need that much cam.
11-07-2005, 11:43 AM
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11-07-2005, 12:49 PM
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The problem with high lift cams isn't the lifter hitting the retainer from the bottom; it's that the lifters fall out of the retainer.
They don't make cams "bigger" by making the tip of the lobe taller. Standard practice with cams is that the tip of the lobe is made as tall as it can possibly be and still be able to install it (the lobes will just barely go through the cam bearings). Rather, since lift is the difference between the back of the lobe and the tip, you make a cam "bigger" by leaving the tip of the lobe alone right where it is, making the heel of the lobe smaller. That's why you can take a worn-out cam and regrind it - remove material - to both renew it and make it "bigger".
When you increase the lift this way, the lifter sinks so far down in its bore at zero lift, that it can come completely out of the retainer.
That machining on the block is not particularly precise, as factory cams don't come anywhere close to the limit. It doesn't have to be. .575" is about the point at which it starts being a REAL GOOD IDEA to check. If you've ever seen what happens when a roller lifter becomes free to rotate in its bore, you'll check them ALL, every time, regardless of what you think the max lift might be. And, you may very well find that the lift limit is different on different lifters, and especially from one side of the block to the other.
They don't make cams "bigger" by making the tip of the lobe taller. Standard practice with cams is that the tip of the lobe is made as tall as it can possibly be and still be able to install it (the lobes will just barely go through the cam bearings). Rather, since lift is the difference between the back of the lobe and the tip, you make a cam "bigger" by leaving the tip of the lobe alone right where it is, making the heel of the lobe smaller. That's why you can take a worn-out cam and regrind it - remove material - to both renew it and make it "bigger".
When you increase the lift this way, the lifter sinks so far down in its bore at zero lift, that it can come completely out of the retainer.
That machining on the block is not particularly precise, as factory cams don't come anywhere close to the limit. It doesn't have to be. .575" is about the point at which it starts being a REAL GOOD IDEA to check. If you've ever seen what happens when a roller lifter becomes free to rotate in its bore, you'll check them ALL, every time, regardless of what you think the max lift might be. And, you may very well find that the lift limit is different on different lifters, and especially from one side of the block to the other.
11-07-2005, 03:01 PM
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Originally posted by sofakingdom
The problem with high lift cams isn't the lifter hitting the retainer from the bottom; it's that the lifters fall out of the retainer.
They don't make cams "bigger" by making the tip of the lobe taller. Standard practice with cams is that the tip of the lobe is made as tall as it can possibly be and still be able to install it (the lobes will just barely go through the cam bearings). Rather, since lift is the difference between the back of the lobe and the tip, you make a cam "bigger" by leaving the tip of the lobe alone right where it is, making the heel of the lobe smaller. That's why you can take a worn-out cam and regrind it - remove material - to both renew it and make it "bigger".
When you increase the lift this way, the lifter sinks so far down in its bore at zero lift, that it can come completely out of the retainer.
That machining on the block is not particularly precise, as factory cams don't come anywhere close to the limit. It doesn't have to be. .575" is about the point at which it starts being a REAL GOOD IDEA to check. If you've ever seen what happens when a roller lifter becomes free to rotate in its bore, you'll check them ALL, every time, regardless of what you think the max lift might be. And, you may very well find that the lift limit is different on different lifters, and especially from one side of the block to the other.
The problem with high lift cams isn't the lifter hitting the retainer from the bottom; it's that the lifters fall out of the retainer.
They don't make cams "bigger" by making the tip of the lobe taller. Standard practice with cams is that the tip of the lobe is made as tall as it can possibly be and still be able to install it (the lobes will just barely go through the cam bearings). Rather, since lift is the difference between the back of the lobe and the tip, you make a cam "bigger" by leaving the tip of the lobe alone right where it is, making the heel of the lobe smaller. That's why you can take a worn-out cam and regrind it - remove material - to both renew it and make it "bigger".
When you increase the lift this way, the lifter sinks so far down in its bore at zero lift, that it can come completely out of the retainer.
That machining on the block is not particularly precise, as factory cams don't come anywhere close to the limit. It doesn't have to be. .575" is about the point at which it starts being a REAL GOOD IDEA to check. If you've ever seen what happens when a roller lifter becomes free to rotate in its bore, you'll check them ALL, every time, regardless of what you think the max lift might be. And, you may very well find that the lift limit is different on different lifters, and especially from one side of the block to the other.
Very interesting. I always wondered that
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11-07-2005, 04:52 PM
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Originally posted by sofakingdom
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