What is the difference between a hydraulic cam and a solid cam?
How the factory grinds ones and others?
At first look they are equal... but they are not.
Some camshaft grinder guru? Harold?


pd:excuse my english, you understand the question idea? graemlins/sad.gif graemlins/clonk.gif

A hydraulic cam is designed to work with a lifter that supports the pushrod on a small cushion of oil. In the simplest of terms the lifter is hollow. Engine oil pressure fills the lifter with oil, which pushes up a plunger, which supports the pushrods.

A solid camshaft is designed to use lifters that are infact solid. There is no give or "cushion" like a hydraulic set-up.

I don't know enough to give an informed answer about the differences between factory manufacturing techniques vs aftermarket.

hydraulic lifters are bad (http://www.n2performance.com/cgi-bin/UltraBoard/UltraBoard.cgi?action=Read&BID=4&TID=1&SID=)

One man's opinion anyway. Page one has some interesting math.

again:
who is the difference between a hydraulic lobe and a solid lobe?
why if use a hydraulic cam as if it was solid (lock lifter o with solid lifter) wipe out it?

Solid lifter cams have lash ramps to take up the lash. These raise the lifter very gently until the lash is taken up then they become more aggressive. A hydraulic cam does not have these ramps since there is no lash to take up. You can run hydraulic lifters on a solid cam. You shouldn't put solid lifters on a hydraulic cam, though. Without the lash ramps, the cam will hit the lifter hard and shock the valvetrain. There are special hydraulic lifters that can be run with lash, usually in the .001-.002" range. Regular hyd lifters will come apart if run with lash.

David Vizard mentions in a couple of his books setting hyd lifters near the bottom of the plunger depth, usually about .006-.010" from the bottom. I never figured out what the reasons or advantages of doing this is. Maybe to avoid collapsing the lifter with extreme spring pressure, but I don't know for sure.

Somebady guys in my country locks the hyd lifter and set a short valve lash and use them with stock hyd cams.
I thing that they are mistaken, but I don't have theoretical foundations to refute them

Yes, you can run solids on hy- camns b/c Harold told me so as well as several other guy's have mentioned it!!

BUT they all run really tight lashes!!! Like .004" to .006"!!! Not .022" to .026" or even the great old 30-30 solid cam at .030"/.030"....

pdq67

Originally posted by pdq67:
Yes, you can run solids on hy- camns b/c Harold told me so as well as several other guy's have mentioned it!!

BUT they all run really tight lashes!!! Like .004" to .006"!!! Not .022" to .026" or even the great old 30-30 solid cam at .030"/.030"....

pdq67 Are you sure they weren't talking about roller lifters?

if you had a solid hydraulic cam would it help to have some type of high pressure oil pump. perhaps if the oil pressure was high enough it would help to keep the lifter "pumped up". Im just thinking out loud but does any one think that this could help to prevent valve float and increase the rpm range of hydraulic cams.

Most cams wether hyd or solid have some sort of clearence ramp... almost a precam just to get things started.... A hyd lifter cams clearence ramp is very short compared to most mechanical lifter cams.

A hyd lifter is designed to operate at zero lash and a preload....IE depressing the lifter plunger .020 - .060 down into the lifter body. Approx .040 is typical. This will provide quiet operation and long service life.

You can run a solid ( mechanical ) lifter on a hyd cam but due to the extremely short clearence ramps ( if at all ) on most hyd cams they cannot tolerate much lash.... A mechanical lifter has no internal mechanism for self adjustment like a hyd lifter does.... This means that if you set a solid lifter cam at zero lash... when the engine heated up and expanded then the valves would never close.
Once they got hot you would in effect have zero lash plus a preload on a lifter that cant deal with it.... so a mechanical lifter cam is designed
with a specific amount of clearence or lash... this allows the engine to run perfectly once warmed up and everything is expanded.... If set correctly a mechanical lifter cam runs perfectly either hot or cold just like a hyd cam does.

Due to the longer clearence ramps of a mechanical lifter cam , that gently takes up the lash and gets the tappet moveing once the lash is taken up..... if you intalled a hyd lifter on a mechanical lifter lobe and then set the hyd lifter at zero lash and a preload... the lifter would react to the long gentle clearence ramp of the mechanical lifter lobe and in effect your seat timeing would be dramatically longer.It can be done but the results would be terrible.

By far the best thing to do is use a hyd lifter with a hyd cam and a mechanical lifter with a mechanical cam..... They are totally different designs and really work best when used as they were designed to be used.

if there were no leak path there would be virtually no difference between hydraulic and solid because hydralic oil really does not measurably compress, but if there is a leak path then there will be a "softening" of the transfer of energy with a hydraulic lifter as it "bleeds" off some of its height dimension. since there is a leak path there is a real difference.

There are at least 4 small block chevy Ultradyne cams that are "mechanical" bur are really hydraulics run with solids, or that is how it looks on paper.

Here's the specs:

MECHANICAL TAPPET CAMS
DURATION AT SEAT IN/EX LOBE SEPARATION GROSS VALVE LIFT IN/EX DURATION AT .050" IN/EX TYPICAL APPLICATIONS POWER RANGE
256/256 =272H 110 .454/.454 225/225 Excellent street performer. Works in 262-350 engines, 2- or 4-bbl, with all stock parts. Idle-5200
264/264 = 280H 110/105 .470/.470 232/232 Very responsive street cam. Works with power accessories and stock parts Idle-5500
272/272 = 284H 110 .485/.485 238/238 Very good performer on the street, more high-lift area than CC 282S. 2000-6200
272/282 = 284/288H 112 .485/.503 238/248

I believe Pdq got these off of Harold's site before Ultradyne shut down?

Some race hydraulics do have a lash setting of .001-.003" , don;t they guys?

There are at least 4 small block chevy Ultradyne cams that are "mechanical" bur are really hydraulics run with solids, or that is how it looks on paper.Ummm... I'd check with Harold. Maybe this is true, but I sorta have my doubts. I think the "= 272H" is just there to show that the cam will behave like a 272H, NOT that it is the SAME cam.

Originally posted by 427L88:
Some race hydraulics do have a lash setting of .001-.003" , don;t they guys? =
Yes ;)

I've understood that in compairing Hydrolic cams to solid at .006 you loose about 8 degrees of duration on the solid.(ramp for the solid lifter) This another reason cams should be compaired at .050.

Jim

Originally posted by JLerum:
I've understood that in compairing Hydrolic cams to solid at .006 you loose about 8 degrees of duration on the solid.(ramp for the solid lifter) This another reason cams should be compaired at .050.Jim You have to add about 8º @ .050" to the solid to compare it to a hydraulic. This is due to the lash. When the lifter has risen .050" on a solid cam, a fairly sizable portion of that .050" is used up taking up the lash. Don't forget the .050" and the .004"-.006" is tappet lift not valve lift.