GM roller lifters w/ aftermarket cam?
02-18-2003, 08:50 AM
#11
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Mr. Moore, are you smoking dope??????????
Call ANY cam manufacturer and ask them. One of us is wrong!!!
IFf you have a cam reground, then they do cut the base circle to creat the lift. Otherwise, they use the SAME base circle diameter on most cams for any engine.
Call ANY cam manufacturer and ask them. One of us is wrong!!!
IFf you have a cam reground, then they do cut the base circle to creat the lift. Otherwise, they use the SAME base circle diameter on most cams for any engine.
Last edited by blown1500; 02-18-2003 at 08:52 AM.
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02-18-2003, 09:57 AM
#13
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Going with Blown on this one.............except for the comment. Don't know if you guys are just messing with each other, or not, but I'm just here to offer my thoughts.
There comes a point where when you get to a certain lobe lift (the higherst lift point of the lobe at the same height as the bearing journal), you would have to take off of the base to get more, because it (the lifter) starts out closed at a lower point, which allows more lift with a given lobe......(it still has to get to the highest point on the lobe) Simple as that. As for regrinding to get more lift, Blown's got it right.
Just my opinion
There comes a point where when you get to a certain lobe lift (the higherst lift point of the lobe at the same height as the bearing journal), you would have to take off of the base to get more, because it (the lifter) starts out closed at a lower point, which allows more lift with a given lobe......(it still has to get to the highest point on the lobe) Simple as that. As for regrinding to get more lift, Blown's got it right.
Just my opinion
02-18-2003, 10:24 AM
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Seems to me that a properly desingned lobe would take full advantage of the journal diameter....this being evident in newer engines where the trend has been to increase journal diameters, as a further attempt to gain control over valve train action. I would bet that there are alot of cams out there for BBC that have their lobes ground on smallblock [or other] masters. I have a cam that I had Crane grind for me for a port F/I application With a BBC intake lobe and a smallblock exhaust lobe...when installing, it is as Denny says, the intake lobes are just slightly smaller than the journal dia. and the exhaust lobes, even though they have more lift, slide in with more clearence[figurtively speaking]. Blown, you say "one of us has to be wrong" I say both of you are right, but I think Denny is "Moore" right if the cam is properly designed.
02-18-2003, 04:02 PM
#17
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OK, Guys,
I called the manufactureres like I suggested you do. They said they take part off the base circle and add part to the nose. For instance, if one lobe has .040" lifter rise more than another lobe, they take .020" off the base circle and add .020" to the lobe nose. We were all 1/2 right or 1/2 wrong, however you look at it.
I called the manufactureres like I suggested you do. They said they take part off the base circle and add part to the nose. For instance, if one lobe has .040" lifter rise more than another lobe, they take .020" off the base circle and add .020" to the lobe nose. We were all 1/2 right or 1/2 wrong, however you look at it.
02-18-2003, 06:30 PM
#18
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Drinking BONG water there 1500...lol
I believe what Dennis is saying, is that by increasing lobe lift by lowering the base circle of the cam, you also lower the lifter in the bore, and I believe that was the concern here, whether related or not. I will also say that Dennis knows his she-it, and ya might wanna take some notes and learn something.... ~grin~
I believe what Dennis is saying, is that by increasing lobe lift by lowering the base circle of the cam, you also lower the lifter in the bore, and I believe that was the concern here, whether related or not. I will also say that Dennis knows his she-it, and ya might wanna take some notes and learn something.... ~grin~
02-19-2003, 08:14 AM
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BGII - so did all this answer your question ?
(in all sincerity sorry, sometimes we get a little philisophical & sidetracked).
If you're not 100% confident in the lifters will work (I personally like to have a bit of peace of mind when thousands of dollars are going around thousands of times a minute), maybe see if you can go down to a local marina, or speed shop, and see what they'll give you for the lifters, I take it they're new. Take that cash, make up the difference, if any, and put it towards the recommended lifters Crane recommends for your application.
Just another thought.
(in all sincerity sorry, sometimes we get a little philisophical & sidetracked).
If you're not 100% confident in the lifters will work (I personally like to have a bit of peace of mind when thousands of dollars are going around thousands of times a minute), maybe see if you can go down to a local marina, or speed shop, and see what they'll give you for the lifters, I take it they're new. Take that cash, make up the difference, if any, and put it towards the recommended lifters Crane recommends for your application.
Just another thought.
02-19-2003, 04:58 PM
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It is simple if the push rod stroke is longer when the base circle is smaller because it is starting from a lower level the rocker will push the valve open more making a higher lift.
Last edited by seahawk; 02-19-2003 at 05:00 PM.
