Ritter Dyno Mule
- Thread starter Earlie A
- Start date
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Un Ground Lobe
Icetech
Well-Known Member
damnit... i tried
PRH
Well-Known Member
UGL…… In other words, “round”.
Most cams start out as a semi-finished core, which already have lobes with a certain amount of lift, duration, and lsa.
Those unfinished lobes are then transformed into the specific lobe profiles by the cam grinder.
Most cams start out as a semi-finished core, which already have lobes with a certain amount of lift, duration, and lsa.
Those unfinished lobes are then transformed into the specific lobe profiles by the cam grinder.
NC Engine Builder
Grumpy Old Man
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This one was tool steel, not sure how they come as blanks
Icetech
Well-Known Member
PRH
Well-Known Member
Back from the cam dr?
NC Engine Builder
Grumpy Old Man
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Still waiting
I could be wrong, but I'd expect they are just lathe turned from a hunk of appropriate rod to set the spacing and diameters of the lobes and bearing surfaces. The gear would be hobbed at some point as well. Would be quite a bit more material to grind for the lobes unless they rough that in as well. Lot easier to do it today with CNC than 30-40 years ago.
PRH
Well-Known Member
One benefit of tool steel(not sure it it’s the case with all tool steel cores), is the material is the same usable hardness thru and thru.
So if starting with something like an UGL core, you can grind pretty much any profile you want……and not have to heat treat it after roughing it in, and then finish grinding it after it’s heat treated(which is how it’s done with normal billet UGL cores).
So if starting with something like an UGL core, you can grind pretty much any profile you want……and not have to heat treat it after roughing it in, and then finish grinding it after it’s heat treated(which is how it’s done with normal billet UGL cores).
Icetech
Well-Known Member
My what lumpy lobes you have....
Just trying to keep it light.. i know you guys are beat up at this point
PRH
Well-Known Member
I’m trying to picture this is my mind…….
Is it possible the lifter bank “angle” of the block is correct, but the lifter bore “spacing”( from left bank to right bank) is such that the lifter wheels don’t contact the cam on the center of the lobe?
If the spacing were off, you’d have a situation where a line down the center of, and parallel to the lifter bore, wouldn’t intersect the centerline of the cam tunnel.
Too far apart and the line is below the cam tunnel c/l, too close together the line is above the c/l.
Is it possible the lifter bank “angle” of the block is correct, but the lifter bore “spacing”( from left bank to right bank) is such that the lifter wheels don’t contact the cam on the center of the lobe?
If the spacing were off, you’d have a situation where a line down the center of, and parallel to the lifter bore, wouldn’t intersect the centerline of the cam tunnel.
Too far apart and the line is below the cam tunnel c/l, too close together the line is above the c/l.
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Earlie A
Well-Known Member
It's a bit tough to determine exact included angle between bores and if the lifter bores are aimed directly at cam center, but I believe @NC Engine Builder is working to verify all of that. We took some rough measurements yesterday with the heads still on. He has the heads off today and has a better reference surface.
PRH
Well-Known Member
Where’s that 48* BHJ lifter true fixture when you need it.
i see you like them round boys too...
here's a stark visual comparison for those that don't quite know, this in contrast is a stock 340 cam:
NC Engine Builder
Grumpy Old Man
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I believe I get what @PRH Is getting at. I rigged up a shaft through the center of the cam tunnel, and indeed, the lifters are biased below the centerline of the cam/tunnel. I'm thinking the lifter bank angle is correct, but perhaps the horizontal location is to high. I dont really know if that's a issue or not. Tried to photograph as best as I could
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NC Engine Builder
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A engineering blueprint of a 48° R block would be handy right about now.
My STX 20 lobes look like the high dwell lobes in the 1st picture...
TT5.9mag
Two atmospheres are better than one
Hard to tell from the pic, but both sides? Or just one side?
NC Engine Builder
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Both.
Earlie A
Well-Known Member
Intake lobes 1, 6 and 8 were run on the cam doctor. They are within 1.5 degrees of theoretically correct location so the cam is not the problem. This cam was supposedly ground on a Landis grinder so I am a little surprised by the one lobe being 1.5 degrees off. But again, the cam is not the source of the problems.
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