Rev kit / Valve float

Rev kits are an ultra high rpm device, used with solid lifter cams. I've never seen them used in an application like yours. Which hydraulic roller lifters are you using? How much lift does your cam have? Which valves, springs & retainers did you install?

I ask because the Ford style lifter will just not rev as well as the Crane style lifter. But this is also dependent upon the profiles of the camshaft lobes, the spring and weight of the valve assembly, which is why I asked about the valve & retainer.

The higher you want to rev this stuff, the more critical becomes the camshaft lobe profiles, using the right lifter, light weight parts & adequate spring tension.

cowboy from hell

Hello George
Comp cams custom made the cam according to the specs of the engine and also delivered the pushers ( I do not have the cam details here at home). Double valves with damper, preasure 145 pounds. valves stainless, steel retainers ( came with the CHI heads).
I know we could get 200-300 rpms by using titanium stuff, but based on experience with other engine builds, my "Dyno whizzard" proposed to ad a rev kit. This is available for other engine brands, and ads about 1000 rpms.
The info I got is that the weight of the hydraulic retrofit lifters/assembly is to heavy to rev as high as I aim for( 6500 - 6700 rpm)
Best regards
Frode
#1155

The rev kit is designed for solid roller lifters, not hydraulic roller lifters. I'm not aware of any on the market for the Ford engines, mainly SBC & BBC.

Comp Cams sells two styles of hydraulic roller lifter, the Ford style & the link bar style. Which type went into your motor.

What rpm limit did comp Cams quote with the lifters & springs they supplied? Did you use the springs Comp supplied or recommended, or did you use what came with the cylinder heads?

cowboy from hell

I would solicit Dan Jones input. The crane hydraulic roller lifters have been used up to 7700 rpm without valve float.

I looked at using a hydraulic roller valve train. I think if this is the route you choose you would get the most rpm by using the Crane lifters in combination with a Comp cams beehive style valve spring.

Yep, that is what I am going to do too. Dan says that building an engine that will withstand 7500 RPM running is a tall order but it is possible. For the valves you need to go to the Titanium so that your valve springs do not have to have such a high force. He said you also need to make sure you have a good cooling system including oil. That will kill ya real quick if than having a spike in oil temps. You also may need to re-enforce the block, George can tell you how to do that. And make sure everything is balanced and blueprinted down to the gnats behind. Oh yeah and use air craft qualit bolts on everything and roller lifters too. Keep forces as low as possible, use an aluminum flywheel. And I am sure I am forgetting a lot of stuff, but Dan and George will remember the stuff I forgot for sure.

Last info I got from Comp Cams, is that it might be the hydraulic lifters "Pump up".
To check this we will adjust the valve/rocker clearance, to be much looser than 3/4 turn.
Results from the dyno tomorrow.
Frode
#1155

Best your going to get with Hydraulic lifters is about 6000 rpm. If you knew you wanted to get more RPM why not use solid lifters ??? Is the motor making power above that rpm ??? will the bottom end of that C motor hold up above that rpm ?? I think your headed down a path of destruction ..

Ron

You can easily get more than 6000 rpm with a hydraulic. A friend of mine has easily hit 7000. Another Pantera owner I know shifted at 7800 and I could easily turn over 7000. Just check the springs you have and make sure you dont have too much oil pressure. If you run 90 psi of oil pressure at high rpm it will pump up the lifters and hold the valves open. 60 psi is fine.

Todays result at the dyno.
Changed the valve springs, installed titanium retainers, oil preassure 70 psi, and tried different rocker/valve clearances.
result : 6300 rpm.
Same hp an torque.
Need rev kit., and will probably make one durin our 4-5 months long winter season.
Best regards
Frode
#1155

So remind me ... why would you rev a motor at a higher RPM and get the same HP and Torque ???

Ron

Frode,

The good hydraulic roller lifters, made by both Crane and Comp Cams, are tied together in pairs by flat link bars.

The Ford style hydraulic roller lifters have flats machined on two sides, and are oriented & retained by a "dog bone & spyder" assembly. These Ford style lifters do not have the same rpm capability as the better link bar style.

Comp Cams sells both types of lifter. You have never said which type you have. If you have the Ford style lifter, you will not attain much more rpm than what you have already achieved.

Why does your motor need a rev kit, when every other Ford motor running a hydraulic roller cam gets by without one?

the camshaft lobe profiles of a hydraulic roller cam are not aggressive enough to warrant a rev kit.

Good luck.

cowboy from hell

What did your dyno hp curve look like. Did it take a big dump at about 5500? Are you using original style mufflers? If so, you might be suffering the problem many panteras have with a restriction in the exhaust. Before you do anything else, you might want to try taking the mufflers off and running open headers for a dyno run. I suspect you can then pull to 7 grand. My car and my friends cars that pulled high rpms all ran the Hall Big bore exhaust.

Hello and thks for the feedback.
I am using the link bar lifter type.
As I like the result to be as close to the reallity as possible it is hooked up on the dyno with the exhaust system that will be used in the car. The set up is the largest headers I could find,that fits in the Pantera. Tube 2", and the collector beeing 2,5". The mufflers are 4 pcs "cherry bombs" with chrome tips. I bought the Hall big bore headers ( 1,7" tubing and 2" colector), but have not used them, as I thought they might be to restrictive.(for sale unused!)
I will post the dyno cheet tomorrow.
Max output is about 5000 rpm. then drops, and at 6300 it looses its breath.
Frode
#1155

Frode,

its good to read you are running the "good" lifters. If the motor is falling off there are a few areas to check:

>carburetor too small
>throttle plates not fully opening
>insufficient fuel supply
>air/fuel ratio too rich or too lean
>restrictive exhaust
>ignition performance dropping off
>the ignition timing is off
>camshaft timing is off
>camshaft grind is too mild
>valve float (not enough valve spring, lifter pump up, too much lifter pre-load)

Peak torque at 5000 rpm indicates to me you have a fairly hot camshaft, so the camshaft grind shouldn't be the problem. It would be unusual for peak torque & peak BHP to occur at the same rpm, normally the peak BHP is 1000 to 3000 RPM higher than peak torque. So it sounds as if performance is still dropping off at 5000 rpm. Your dyno operator should know if the fuel supply pressure was holding, and if the air fuel ratio was where it should be. If you are running a 4 barrel carburetor, it should be at least a 750 Holley/650 Demon, preferably 850 Holley/750 Demon to hit your target rpm.

Ocasionally a situation occurs where the carburetor butterflies (throttle plates) do not open completely. One way in which this happens they can hit the intake manifold. With a vacuum secondary carb the secondaries can stick closed, or if the diaphragm is bad, just fail to operate. Dave's point about the exhaust is also well made.

Again, good luck my friend.

George

Hello Guys
Pls. check the attached dyno sheet.
We use Holley 950 commander EFI system.
Car to be street driven.
Best regards
Frode
#1155

I like the wide torque curve, above 490 ft/lbs between 4200 & 5700 rpm. I do not like the torque curve above 5700 rpm.

The air fuel ratio looks OK between 5100 & 5700 rpm, everywhere else its too rich (there's a step in the motor's output at 6100 rpm where the a/f is OK too). What did your dyno operator comment about the a/f ratio?

cowboy from hell

Yes agree it was making 350hp at 4000rpm .. nice but at 5800 things change I'll bet either exhaust restriction or intake air restriction. Looks like intake .

Ron

I really enjoy this forum !!!
As I started this topic, my focus was the rpm at top. During our tests last days, we have changed some parts, and adjusted the setting of the EFI / computer. We know the mapping is not 100%, but a bit on the rich side. These adjustments to be a part of the daily amusements to come ! However I still believe the hydraulic roller system is incapable of higher rpm, without help of a revkit.
I do not like to use the solid lifters, as having to adjust valve clearance each week is not what I care to do.
So the question remains. Anybody offering a revkit for the Cleveland engine ?

Best regards
Frode
#1155