[rascal455ho]

Standard not roller?

[David Jones]

Not for long.

[screamingchief]

Originally Posted by David Jones

Not for long.

I tend to disagree,,,but the real issue would why anyone would want to do such???

There is nothing inherently unique about the exterior of a solid flat tappet lifter vs. a hydraulic flat tappet lifter,the differences are pretty much all internal,and how that specific feature relates to the lobe shape being used.

If anything a solid lifter on a hydraulic cam lobe would have a harder time living as opposed to a hydraulic lifter on a solid cam lobe.

The solid lifter has no "cushion" to it internally,thus it needs the lash in the valvetrain,the lash allows room for expansion to keep the valve(s) from staying off the seat (and thus losing compression),and the "lash ramp" is there to keep the valvetrain from abruptly snapping open and shocking the valvetrain unecessarily,the lash ramp on the solid cam lobes allows the lash to be taken up gradually before the lobe really starts to do it's thing.

Using a hydraulic lifter on a solid cam is just defeating the whole purpose of the lash ramps,as they become redundant.

Hydraulic cams have no lash ramps,the internal lifter mechanism allows the valve to close completely in spite of having no lash in the valvetrain,so they have no need for lash,they use preload instead.

Using a solid lifter on a hydraulic cam with no lash ramps is where this deal becomes a crapshoot,it can work fine in some cases,in other cases it does'nt work very well at all.

And if you do this (solid lifters on hydraulic cam),you will still need some lash in the valvetrain,though typically not as much lash as you would run with a true solid cam.

[71 Ventura II]

There are a few companies like Herbert Performance and Howards Racing Components who sell cams listed as "solid" or "Hydraulic". I agree you could run hyd lifters on a solid cam with relatively no ill effects. I have seen a ton of people running "Claimer" engines throw solid lifters on a hyd cam but they don't last very long. Darn dirt trackers will do what it takes! JD

[David Jones]

Isn't the spring pressure required to keep a lifter on a solid cam somewhat higher than on a hydraulic cam. Would that pressure not quickly kill the hydraulic lifter?

[screamingchief]

Originally Posted by David Jones

Isn't the spring pressure required to keep a lifter on a solid cam somewhat higher than on a hydraulic cam. Would that pressure not quickly kill the hydraulic lifter?

Not necessarily.

If one has an fairly radical solid flat tappet cam,one might run a bit more spring pressure,but most SFT cams dont require any crazy spring pressures.

But honestly the same can be true for HFT cams as well.

Once a fella gets to a certain point with regards to upping the spring pressures while using flat tappet cams,he'll begin to start using hardware like tool steel lifters with oiling mods (EDM oiling or grooves or such),and nitrided cams to help such live with the higher spring pressures.

The problem with hydraulic cams in terms of spring pressures is you'll reach a point where the pressure becomes too great for the internal hydraulic action to deal with,at that point there is little else to do but switch to a solid lifter.

Now with that switch to a solid cam & lifters,a fella can indeed run a bit higher spring pressure,that is,if he wants to,but often it's not really needed per-se.

That additional spring pressure is not really needed till the cam passes a certain threshold in terms of it's "size" or it's "aggressiveness" in terms of lobe shape,or till very high RPM useage is in the playbook.

When a solid cam is needed for whatever reason,yeah sure some will often choose to run a little more spring pressure than one typically would use with a hydraulic cam,but that is'nt all that much difference with a hydraulic cam & lifters,the hydraulic lifter body itself could handle the same higher spring pressures as the "radical" solid cam & lifters if it needed to,it's just the internal mechanism that will begin to struggle with the higher spring pressures,not the lifter body itself.

HTH

Bret P.

[joes455]

I wonder how the closing of the valves of a solid cam would react to a set of rhoads lifters.Would the valve smacking the seat be louder or softer.