3.98 stroke Scat cast steel or forged crank balance

[blykins]

Yes, it will all boil down to what the heads are and how well they work.   For instance, a TFS head on a 390 will make about 540 hp @ 6000-6200 with a hydraulic roller.  I have also made 540 hp with a 390 and ported CJ heads with a hydraulic roller, at 7000 rpm. 

The solid roller lifters require more spring pressure because of lash.  It takes more spring load to keep things from bouncing around uncontrolled.  It also will depend where on the lobe the actual lifter contact takes place as it may accelerate the lifter and that also requires more spring load.

It would be hard to not want to use solid roller lifters if you already have them.   It would save you money.  However, if I were planning to use solid roller lifters, I'd stick them on a solid roller camshaft with moderate lobe aggression.   Comp Cams also has a few lines of hybrid lifters that aren't visible in the lobe catalogs.  They kind of bridge the lines between hydraulic and solid.  I've used them with both style lifters successfully.  If you could sell them and buy a quality set of hydraulic roller lifters, you could hit your horsepower and rpm goals and not have to worry about the lifters down the road.

[Barry_R]

You can use solid roller lifters on several of the Comp hydraulic roller lobes.  As noted, they run with minimal lash, and can do surprisingly well.  Most traditional solid roller cams were designed for racing applications with profiles and RPM bands beyond anything appropriate for a cruiser style street car.  These hybrid lobes do fill the hole, although custom stuff is possible that would likely do a better job.

The need/desire for more spring is to keep that solid roller in contact with the lobe as much as possible - rollers do not like impact loads - each roller needle is essentially "point contact".  Hydraulic rollers do not share that problem since the preload ensures that the roller is always in contact with the cam.  Valve float in a hydraulic roller makes for a bunch of noise and a huge power drop-off.  Valve float in a solid roller makes for busted parts.

You can theoretically run solid rollers with far lower tension springs than we normally see in drag cars - but doing so requires a level of research and analysis far beyond that used in a common street/strip application.  If we are to believe what's reported on the web, there are Cup engines running 9,000+ RPM with spring pressures that we might find marginal in hydraulic applications.