Corvette Kid

Such as this.
I'm looking at these parts and trying to envision just exactly where they all go. I understand that they are providing additional tension on the lifter body. I checked the installation instructions on their site but they don't cover this kit.
If the possible HP gains are even half of what they claim at higher RPMs, it seems like a bargain for the price. I'm current running a '95 388 LT1 stroker w/ Hotcam, fully ported factory heads w/ 2.02/1.6 valves at an installed height of 1.8", 1.6 Pro Mags and 26918 CC beehives.
Although this car is sometimes raced, it's a daily driver that averages 10K miles a year. Is this something that would function reliably in my case? Although I don't spend a lot of time in the upper RPM ranges, it'd sure be a kick in the *** to have such a HP boost up there when I wind it up.
They mention needing a tool for compressing the valve springs if the kit is installed w/ the heads on the engine. That's fine, I have both the lever type and the one that goes over the spring, hooking into it and pulling it together as the tool's tightened.
Anyhow, any and all information on these kits would be much welcomed.

Deakins

Well the only way an engine looses that much power up top is from valve float; that's caused by inadequate valve spring pressure. The rev kit can help the lifter stay on the cam but can do nothing for the valve. The main reason we run rev kits in race engines comes from the link bar solid roller lifters we use in most applications. When we have a top end valve train failure what tends to happen is the pushrod flies up and out of the way allowing the lifter to come out of its bore. Once it does that the lifter that it's liked to will tend to turn sideways and start destroying the cam, its lifter bore, and run metal throughout the engine until the driver gets it shut down. With the rev kit, the lifter on the problem side should stay in its bore and keep damage to a minimum.... With a factory roller block you have already eliminated this threat...

machineman

I generally do not run a lot of rev-kits on street engines but they do have their place. The original intent was on solid roller cams to keep the lifter in constant contact with the cam lobe. When you get bounce at high RPM, you not only lose HP but you damage the parts and a failure is not too far from that point.

What you have to think about is if your engine is even making power in the problem RPM range to warrant making the purchase. I would however not buy this and expect to see 100 HP on the dyno in every situation.

Ironcross

And positively should be used with solid lifter engines as described above. A hydraulic cammed engine will probably never reach the effective RMM`s the solid cam uses to make HP....

Corvette Kid

Odd that two of you should mention solid lifters since AFR specifically makes mention of them being important for hydraulic ones, which mine are. I'm not doubting your words but simply making the observation. My engine makes peak HP at around 6000 RPM and so never sees over 6500 tops. The spring pressure at the maximum lift of my cam (.525") are at just under 300 lbs. So do you think this kit would be of any benefit to me? Thanks in advance for your thoughts.
BTW, even if the upper RPM power increase isn't great, if it'd be beneficial to valve train stability in my application, I'd be interested. Although my bottom end is built to take more RPM than it'll ever see, as you all know, all it takes is one problem in the top end to turn it all into junk.

gkull

If i owned a H-roller it would have a rev kit and a sequential rev limiter. Valve float is very destructive.

Valve train weight is a big deal. Springs required to counter act valve float with H-rollers is often exceeded in the low 6000 rpm range.

Quality digital rev limiters is really the best answer when you are running on the valve train red line edge. I have so much faith in mine that I will run it into the rev limiter instead of shifting. You hear it all the time while watching lapping cars

black bart

I have a supercharged 406 with a H-Roller and A rev-kit been driving it for 7 years without a problem.
I have a retro-fit roller in a 400 block and would not consider running without the rev kit.
Small price to pay for all the benefits.

Belgian1979vette

Deakins,

A question : I used a rev kit to prevent the lifters from ever leaving the cam in case of valve float which in case of a roller cam can cause brinelling of the cam. However I did have a problem getting the aluminum bar of the revkit under the head to seat properly. Current day heads have a depression behind the intake manifold face which makes the bar tilt/not sit flat. How do you solve this ? (hope this kind of discribes it right)

Thanks

rklessdriver

Rev kits won't fit some cyl heads because of this. AFRs hydra revs won't fit on Dart and Pro Action heads.

As far as Rev Kits on street engines, you should be running them. They will actually make roller lifters live longer, because the lifter tracks on the cam lobe instead of lofting over the nose of the cam and crashing down on the closing ramp skidding the roller and brineling the roller bearings. Ed Iskiderian and John Reed were the biggest proponets of rev kits that ever were because of this fact. Isky actually told Joe Sherman that test he conducted proved a rev kit would double the life of roller lifters. John Reed said the same thing everytime my dad and I went to Reed Cams to pick up a shiney new roller cam. The reason a lot of people don't run them all the time is... They actually cost HP, because of friction. Typically on OUR oval track engines they take about 15-20hp (this is a 780hp engine) but they are endurance engines so we can live with the slight hp loss. Joe Sherman said he had seen losses as high as 40hp on some of his 850hp+ drag motors (hence why he rarely uses them).

Kid.

The AFR hydra revs are worth their weight in gold on a high reving hyd roller motor. Hyd roller lifters are extremly HEAVY compared to mech roller lifters and some cam companies have hyd roller lobes that are just flat too aggressive (retro fit lifters are even heavier than factory hyd rollers) for the normal confines of a what most would use a hyd roller cammed engine for. Hyd roller cams are nice but your kinda damned in some ways with hyd roller cams, they are nice as the lobes can be way more aggressive than flat tappets once you get past .200 lift and you still get to keep that zero lash stuff we love so much (no one likes adjusting valves all the time). However you can't get too crazy with your lobes because your limited by valve spring pressure. For the most part once you get over 350-400lbs (over the nose) you will collaspe the lifters plunger (althou there are special hyd lifters and ways to modify lifters to take more pressure and = more RPM).

The Hydra Rev is a nice addition to help stabilize hyd roller cammed valve trains that my be on the edge lobe profile, valve spring and RPM wise. But its not MANDATORY for every hyd roller cammed engine in the world either. 6000 RPM is just not anywhere near that edge. IMO if someone was having problems at 6K they need to re-evaluate their cam lobe selection and valve springs first as they have something horridly mis-matched there.
Will

Belgian1979vette

For now I taped the aluminum bar for a bolt that would support the bar under the head in the middle. I used red loctite to lock to bolt in place, however I not completly satisfied and still worry about that bolt being there.

1981Z06Vette

David Vizard is a big fan of the rev kits for hydraulic roller motors...thats good enough for me.

vetteman9368

A properly thought out and designed valvetrain will not require a rev kit. reduce valvetrain weight, particularly on the valve side of the rocker arm. Run a larger, stronger pushrod (even at the addition of some weight) and reduce flex as much as possible. Flex, and the resulting harmonics contribute more to loos of valvetrain control than anything else.

cv67

With the GM Hotcam I wouldnt bother, not big enough to worry about.