The Stovebolt Site Forums The Shop Area Engine Shop hydraulic vs solid cam profile specs

Does anyone have cam data for the hydraulic lobe profile, and for the solid lobe profile for 235 full pressure engine?
Does anyone have side by side pictures of the two camshafts?

There won't be a visible difference in cam profiles, since the only real change is to a very short section of the lobe where the base circle meets the lift area. The only way to evaluate the profile changes will be with a degree wheel and a dial indicator. Plot the lift curve on a piece of graph paper with measurements about every 5 or maybe 10 degrees.
Jerry

I guess that must be why I can't tell one from the other looking at them side by side.
Unlike what is clearly visible when comparing V8 cams side by side. The hydraulic cam on a V8 looks like a slightly oblong circular profile, while the V8 solid cam profile looks like a Stovebolt cam.

I don't know if you can see it but the solid profile is more aggressive. You can open a solid lifter faster because they don't squish. Open it faster and you can keep it open longer. since solid lifters don't squish you can run tree stumps for pushrods and not worry about weight. Just have someone throw it on a cam doctor machine. It's not expensive. JMHO.

A set of V blocks to support the cam, a degree wheel, and a dial indicator is all that's really required- - - - -along with maybe 40 or 50 years' experience at blueprinting engines. Remember that every one degree of camshaft rotation represents two crankshaft degrees. I've never seen anyone with enough of a calibrated eyeball to recognize the difference in two flat tappet camshaft grinds, (maybe with a roller cam?) no matter how much of an "expert" they claim to be. Unless you're running Rhoades lifters, "squish" is a myth. Liquids don't compress.
Jerry

But a little of it can leak thru the clearances in the hydraulic lifters. But it's probably not significant. Kind of like what you say about being able to "eyeball" the difference between cam grinds.

Here's a snip from this website.

"Hydraulic lifters are traditionally thought to have a common weak point: the pumping design. This type of lifter collapses a little as the cam pushes up, and the resistance of the rocker arms keeps the pushrod in place."

At 2K RPM, each lifter is operating 17 times a second. How much can one leak down in that amount of time, as it's being refilled by engine oil pressure every time it rides on the base circle of the camshaft lobe.
Jerry

Like I said, probably not significant. But it does have clearance between the plunger and lifter body. Otherwise, they'd be solid lifters.

That's why solid lifters exist.

Acetylene gas headlights and hand cranks for starting exist, too. They're as obsolete as solid lifters.
Jerry

Hey Jerry,
You got an extra set of NOS hydraulic lifters for a 235 laying around?
I am asking for a friend.

Nope, not at the moment. I'm about to get a setup finished to recontour the base radius of worn lifters, so don't discard any "worn" OEM lifters. They can be rehabbed if they're not badly damaged.
Jerry