What happens when this is done? I know Solid on a hyd cam run real tight.

Both solid and hyd cams have the lobes bevelled in order to spin the lifters. So "hypothetically" either should work with the other. HOWEVER, solid cams usually have a more agressive lobe profile and higher lift requiring stiffer valvesprings, both of which a hydraulic lifter might not handle very well. So when you combine all things there is a reason for what the manufacturers do.

also solids have a lash take up ramp that would cause the hydro lifter to not work properly , solid on hydro cam is fine if run very tight

Are you wanting to do this in hopes of having to not lash valves ?

Nope, just less maintenance. I have 3 solids and 1 roller cam for the Hemi and just thinking of using the pre 1975 hyd lifters I just picked up. I could send one off to be reground for hyd lifters, won’t be a hot rod.

Explain this please. A hydraulic lifter has preload. What is this "ramp" going to do ???

it will cause the seat timing, duration to be MUCH higher at the valve,.020 lash is gone from the solid, also a lot of solids have an inverted flank, the lobe drops a little just before the ramp, the hydro would start opening the valve very early compared to a solid lifter with the proper lash, I tried it many years ago on my 383 dart, ran like crap, no vacuum.

A solid roller has more stuff going on in the beginning and at the end of the ramp to control valve seating velocities with lash in mind. So basically running a hydraulic lifter on that type of profile can result in a lot more overlap and run really lazy. This may not be true in all cases depending on the lobe profile used.
Hydraulic rollers are definitely way more aggressive off the seat than solid profiles. They get away with this because the of hydraulic shock absorber effect and probably some other reasons I can't think of.

For example,
If you look through the comp lobe master catalog and compare the "Major Intensity" numbers, basically the difference in degrees between rated duration and duration @.050 lift on a solid profile you will see what I mean. Hydraulic profiles typically give there rated duration at .006" lift so you just need to look at the Major intensity rating on the left side of the table and compare that to solid profiles. Some of the lazy solid profiles have major intensity numbers in the 32-36 range. the more aggressive profiles are in the 28-30 range. The super aggressive valve train parts breakage stuff is <28 degrees major intensities. The hydraulic roller profiles normally run below 30 degrees and more typically in the 26 degree range and considered extremely aggressive on a solid profile. This is why you see people going solid on a hydraulic with tight lash because of the fast lift off the ramp.
AG.

If the engine you’re considering this on is up and running, and you want to get a feel for how it will behave with Hyd lifters in it…… just set the lash with the solid lifters to nearly zero, and see how you like it.
With the Hyd lifters, properly adjusted, it will be zero lash.
This lets you experience it without swapping the parts.

I've never done this personally and my only practical experience with it is when I was helping tune a Pro 5.0 Racer who had to run a spec lift Hydraulic Roller (like a B303) cam for the class.

They would run the Morel Solid roller Lifter because back then at least, maybe still Morel used the same long Hydraulic lifter body with a Slug inside of it instead of a plunger. They would set the lash tight like .004-.006 (had to run factory iron heads) and they'ed pick up 500-600 RPM and maybe 30-40 more HP

For Flat tappets I would think the faster ramps (and usually stiffer springs) of a solid Cam would make that a 100% no-no.

I have heard of poeple running "near Zero" like .006" lash solid rollers on Hydraulic roller cams...I would think that would essentially be just like having a milder off-the-shelf solid, So maybe if your HR combo was a bit Over-cammed, that might actually be doable. I would think the lighter bodies (like the BAMS) might offset some of the rotating Mass and with a smoother lobe, maybe that's a thing? Has anyone actually done this? Like I said, I have no skin in that game.

But I cant imagine going hydraulic lifter on an aggressive Solid ramp. After all Hydraulics are "rate of lift" limited by design, that's why they still make solids after all...or so I thought.

Just so everyone is on the same page, is the OP asking about flat tappet or roller cams?

I'm thinking flat myself because he referenced some 1975 lifters he has in stock but then the conversation went solid roller vs hyd roller.

Kevin

I’ve tested solid lifters on Hyd cams a couple times.
It was just to verify what we suspected was the problem, was actually the problem……the lifters. And in those instances….. it was.

I wouldn’t even try to run Hyd lifters on a solid cam……..because I don’t feel that it would end up with a satisfactory result.
Id feel like I was wasting my time. But, as always…….”YMMV”

To me, if you want to run Hyd lifters……..the easy button is…….run a Hyd cam.

good question because he says he has 3 solids and a roller ???

Wouldn't running Solid lifters (Roller or Flat Tappet) be basically like running a really Mild Solid cam? And if so, why would the lash be necessarily any different? I'm mean, Why do you lash the valves at only .006? What about aluminum blocks and heads?

Solid or Roller, the metallurgy of a solid cam is as hard or harder and the Hydraulic ramps have a slower Velocity, usually solids have the advantage in that they have the capability of remining stable with faster valve action /ramp rates

The flat tappet cams range from .490 to .580 lift so I’ll stick the smaller one in, set zero lash then see what happens. 4 speed car with 4.15 crank so no need to worry about vacuum loss at idle.