ok so i bought these (jbp) cams for my 2.4l ld9 from a guy in Canada and now i finally got a mike and i go to measure the cams to make sure they are the rite ones/
well i measured the stock frist then the (jbp) the stock have a higher lift on them from the point of the lobe.
After i measured the stock cam i left the mike at the height it measured the stock one at.
Then i went to measure the (jbp) and the jbp cam lube fits in the space the stock was measured at.
so is that what it spose to be like or did i get ripped off???????
Thanks,
Paul
When you regrind a cam, the overall diameter can't increase without welding on new material (which WILL chip off). The increased overall lift comes from having a greater ratio of lobe to cam center / base circle to cam center.
fortune cookie say:
better a delay than a disaster.
wouldnt that require shims, to take up the diff.
Don't steal, the government doesn't like competition
It depends on how much the base circle was reduced. I'm not familiar enough with the DOHC J motors to know for sure, but I've never heard of anyone here using shims before...
fortune cookie say:
better a delay than a disaster.
anyone else iam still not understanding
ok so they shorten the back side of the lobe basically making a smaller circle.
so how is this giving me more lift if the cams lobes are actually smaller??
Sorry Iam just not getting how you regrind a stock cam and get higher lift.
so if you could please explain that me?
Thanks,
Paul
you don't measure lift by measuring the entire overall lobe. you want a dial indicator and somethign you can put the cams on and spin them (such as a couple blocks of wood with V shapes cut in to hold the cam in place) Zero out the dial indicator on base circle and then rotate the cam and measure the hightest point. You don't want to messure the whole cam lobe base circle and all, you want to messure the difference from lobe peak to base cirlce. And on top of that there is ALOT more to cam speaks then just lift, lift, actual duration, ramp angles, lobe shape, valve overlap, ect...
cam lift is the distance from the top of the load to the base circle.
Or, it is also the distance from the top of the cam to the backside of that lobe minus the base circle.
For pretty much all 2.4 cams, you can measure the distance from the top of the lobe to the back of the lobe and then subtract the distance you measure from across the sides of the lobe.
When a stock cam is reground they will grind a smaller base circle to get more lift.
You get more lift because the lifter starts moving from a negative lift when compared to the stock cam.
So if the stock lift was .350" and now its base circle is cut .010" the valve is starting at -.010" relatively. The end result will be .360" lift.
Unfortunately, on a 2.4, if the base is cut much more than .010" the lifter will begin to clatter.
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