Rev kits , hydraulic roller cams.

[Bill Chase]

Just an observation, but in my reading here, rev kits were suggested a lot up until about 5 years ago, now not so much. Afr even stopped offering them for their renegade and eliminator heads

Average power goes up, rpms too, and guys are doing it with hydraulic roller stuff, are valve springs better now?

I guess what I am saying is there are noticable trends, they have came and gone and rev kits seem to be one of them. I understand that valves, and other things are lighter now. But how is it that what was solid roller only lift and duration numbers a decade ago.. is now being done with hydraulic roller deals? And with no rev kits, lighter seat pressure and full lift pressure?

Just trying to learn, hope I am not being to pesky.

[lefty o]

as you said, parts have gotten lighter, but i also tend to think 2 main factors are involved. better quality spring options, and likely better ramps on the cam lobes. imo, a rev kit still offers great insurance.

[Camaromeo]

I have been researching a lot about this topic, too. Hydraulic Rollers go beyond 8000rpm in some engines (SBC, SBF etc.) easily, but BBC is something more critical, due to heady weight.
Todays Top-of-the-line hydraulic roller lifters are capable of taking springs loads that would just destroy lifters from 20 years ago.
Precision and Quality and in the end also just money makes it possible.
Have been talking to Chris straub about BBC Valvetrains and with a good triple springs, shaft mount rockers and an as-light-as-possible valvetrain (maybe even titanium valves), BBC 8000+ rpm hydraulic roller set ups with lifts up to .800+ are no problem.
In other engines like SBC/SBF you mostly just need good lifters/springs/stud mound roller rockers and you are good to go.

How high do you want to rev = How much money do you have?

[CamKing]

One thing to remember. All those "Limited Travel" hydr roller lifters you see, aren't really hydraulic. They're designed to bottom-out, and run as a mechanical lifter.

[RevTheory]

One thing to remember. All those "Limited Travel" hydr roller lifters you see, aren't really hydraulic. They're designed to bottom-out, and run as a mechanical lifter.

So if that's the lifter you plan on running, should you look at solid profiles rather than hydraulics?

[CamKing]

One thing to remember. All those "Limited Travel" hydr roller lifters you see, aren't really hydraulic. They're designed to bottom-out, and run as a mechanical lifter.

So if that's the lifter you plan on running, should you look at solid profiles rather than hydraulics?

If it's a race application, yes.

[PackardV8]

Are there racing classes which require hydraulic lifter roller cams?

[CamKing]

Are there racing classes which require hydraulic lifter roller cams?

Yes. Drag Racing, Road Racing and Circle Track.

[RevTheory]

Mike, if a lobe profile is designed so aggressive on and off the seat that it upsets the plunger, a rev kit won't fix that, correct?

[CamKing]

Mike, if a lobe profile is designed so aggressive on and off the seat that it upsets the plunger, a rev kit won't fix that, correct?

what collapses the plunger, is a combination of lift rates, and pressure applied against the pushrod seat.
If you can use a rev-kit that applies pressure to the body of the lifter, and not the pushrod seat, you can decrease the spring pressure a small amount, which would decrease the pressure on the plunger. It wouldn't be a big decrease in pressure, so it wouldn't help much, but it would help.

[BOOT]

If it's a race application, yes.

Based on rpm or race usually being larger cams?

[CamKing]

If it's a race application, yes.

Based on rpm or race usually being larger cams?

If it's not a race application that requires hydr rollers, run hydr rollers with a hydr roller cam, or mech rollers with a mech roller cam.

[miniv8]

We made a rev kit for a hydraulic lifters, they where not limited in travel in any way. basic cookie cutter cam.
The 383 sbc was happy till 7k.

Best of both worlds.