vfast

not to mention there hard on valve springs

angcobra

Maybe we should back up and separate flat from roller and hydraulic from solid.
You can have rollers for hydraulic or solid. The below may not be a perfect explanation but it should help understand some of the basics of solid VS hydraulic and flat VS roller.

Flat lifter has flat bottom that runs on cam, metal to metal sliding.
Roller lifter has roller (wheel) on bottom that rolls on cam, no sliding just rolling.
Roller has less friction and allows steeper ramps on cam.

Hydraulic lifters use oil pressure inside the lifter to take up all lash or gap between the cam/lifter/push rod/rocker arm/valve spring. You adjust these once (by tightening down on rocker arm) to slightly compress the oil in the lifter. The potential problem with these at high RPM is having the forces get to a point that overcomes the oil force inside the lifter and causing them to compress (some folks call lifter float or colapse) which causes a gap to happen between the cam and lifter. Most of you have heard a car at startup that has a loud tapping noise that goes away in just a few seconds, that is a lifter that is bleeding down when the engine is not running (allowing gap) and then it pumps back up when oil is supplied to it.

Solid lifters, are just what they say, solid from top to bottom. The advantages are no change in gap or valve lift due to lifter float regardless of RPM. The disadvantages are you must have a small amount of gap to allow proper transition up and down the slopes of the cam. With solid lifters you adjust a small gap, usually measured between the rocker arm and valve stem. As parts wear this gap will change and need to be adjusted again. Because you have a small gap on every valve, you will hear the tapping of all valves all the time, that's why they are noisy.

uedlose

With the new cam and spring technology that is out now the Hyd. roller cams will rev. pass 7500+ rpm now with stock Ford lifter if you got the rest of the motor to go with it.I race with a guy some times that runs the Pure street in NMRA and he turns his motor 7800 rpm with a ED Curtis custom grind cam and a stock lifter Anderson Ford also sells high rev cams.also look at the renegade cars in the NMRA they rev well pass 7500 RPM with a stock Ford lifter also.But they are race cars and need to rev that high where as a street car dont need to make power that high.

bobby

so with the new technology, the only reason to go with solid is more power?

86HOGT

NO the only reason to go solid roller is to rev the motor higher without valve float.

bobby

ok i see. but if you get the new lifters or cam or whatever like lose was talking about, there is NO reason to go with solid right?

Aixtreme89

I just got my motor built about 6 months ago. I havent heard of new technology in hydraulic lifters. At about 6700rpm. the hydraulic lifters pump up with oil and cause the valves to remain open. So basiclly thats the highest you can rev your engine. I know with solid lifters you can rev your engine atleast 8000rpm. BUt you have to make sure your rotating assembly can handle it.

Show me an article or anything about these new hydrualic lifters.

bobby

ok, i know what roller is and what solid is, but what is hydraulic? is there a hydraulic roller and just regular roller? and is there a hyd. solid? thanks!

Aixtreme89

If you have the stock crank, rods and pistons in your 5.0. Put hydrualic lifters in. Your engine wouldnt be able to withstand over 7500rpm. Plus hydraulid are trouble free. With solid lifters you have to adjust valve lash on your lifters often.

Aixtreme89

Yes there are hydraulic roller lifters and hydrualic flat tappet lifters. Then there are solid roller lifters and solid flat tappet lifters. For your 5.0 your only conserned about the roller type lifters. You dont use flat tappet lifters.