Cam measurements

[Grego]

Bought a reground camshaft for my 4.0, mild RV1 with a mild lobe lift. My stock .253 and the RV1 .257. I know when they regrind these they take material off the flats to bring the lift up to where they want it. Measuring the flats on each lobe and subtracting this from the lift I do get the .257. My question is when comparing all the intakes on the flats I get as much as a .015 difference, when I measure all on the exhaust I get as much as .034. How is this going to affect my push rod length? The machine shop took .040 off the deck to bring the new pistons to 0 deck height. They also took .005 shave off the head to clean it up. Just looking ahead to see how this might play out. I know you guys play with this kind of thing quite a bit, this is my first build and just trying to understand everything as I go.
Thanks, Greg

One more thing, hoping to use the stock push rod lenth, 1994 4.0 block

[SilverXJ]

Are you measuring the cam lobes with a caliper or dial indicator in V-blocks? Calipers will get you an idea, but not an exact measurement due to the fact that you may be measuring in an area where lift is starting. Also, keep in mind that the lobe has a taper to it as well. Using v-blocks and a dial indicator is a better way to measure, but still the results could be skewed due to the taper as well. The best way is to measure it in the block with a lifter on the camshaft.

Now, if your measurements are accurate I would be contacting whom ever reground the cam.

[Grego]

Measurements were taken very carefully. Already had sent a email out to the manufacture.
Thanks, Greg.

[Retlaw01XJ]

Lifter preload spec is generally 0.020" to 0.060". If you are in that range you should be okay. Apparently, hydraulic lifters can auto-adjust somewhat....That's just what I've read, don't take my word for it! Testing that theory would be difficult on a running engine.
But yes, if there is that much variation, I would certainly question the quality of the cam.

[Grego]

Well according to the manufacturer when they regrind these cams using cores,depending on how much ware is on the lift on the cam lobe determines how much is removed from the sides. As long as the final measurement adds up to the total goal lift it doesn't matter in the lobe difference comparing each measurement. Say on my exhaust difference of .034 divided by 2 that would be .017 difference in push rod height. But the hydraulic lifter would compensate for that.
That is how I understand it.
Thanks, Greg.