Installing roller bearings in stock rocker arm assemblies...

NickTF said:
Dan, I'm not sure I'm following what you're getting at here? Are you suggesting the flat tappet moves the valve more agressively? That's opposite of everything I and many others know about flat vs. rollers. :what:
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I am not saying that, but when you look at the roller cam it will look super aggressive compared to a flat tappet cam.

Picture the roller approaching the cam lobe. You have the radius of the roller.
 
zstroken said:
I am not saying that, but when you look at the roller cam it will look super aggressive compared to a flat tappet cam.

Picture the roller approaching the cam lobe. You have the radius of the roller.
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Ok, I gotcha. Yes, this is correct and will also be reflected if you take two profiles, one flat and one roller, with the same duration at .050" (say 240 degrees at .050" in this case) and compare duration at .006", .200", etc. You'll find duration at .006 is far more in the flat lifter cam indicative of the slow ramp profile and duration at .200 far less in the flat lifter cam further indicative of the slow ramp profile.

I think the reason you don't see roller lifters in diesels (or atleast the cummins) is that they are unecessary expenses and aren't quite as durable in a motor meant to go for 1,000,000 miles or whatever the targeted motor life is. Plus, lets be honest, to make 215 hp (12 v) all the way up to 350hp (CR) that the factory needed with 360", 17 to 1ish compression, and turbo doesn't exactly require the most advancted parts:Cheer:
 
Redstroke, I noticed in another thread you went a different route with your cover. I understand why... What did you use to still be able to get to the adjustable pump gear?

For one I hate to cut off part of my new Fluidamper and have to run a narrower belt. Now it looks like I may have to ditch my stock fan setup too? Not sure yet. The fan mount will have to be relocated farther forward to clear the cover, that's for sure.

H2 cam for now. Billet isn't available yet. I'm leary now that I've seen how small the cam gets after the 2nd journal...
 
Being that we are talking about roller bearings .

Has anyone put Torrington bearings in cam journals?
 
Does this help?

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MAXTORQ said:
Being that we are talking about roller bearings .

Has anyone put Torrington bearings in cam journals?
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installed them in the Predator truck, I have the Bearings it takes, it’s the same amount of work to put them as a slider bearing , AKA hydrodynamic bearings . . The only reason for roller cam bearings is to reduce oil leak in the crank case, for windage reduction
 
How much do you have to machine out of the block for them to fit properly?
 
If I was going to do anything it would be to install a 60mm cam with the thinner roller. I would never install a roller lifter in a Cummins, the lobe profile with a 1.5 tappet is incredible, and cannot be duplicated with a roller lifter. This is a mathematical fact. The only reason for a roller lifter is extreme RPM’s as in Super Stock Tractor engines that turn 7500 rpms and the necessary spring pressure needed to do this would wipe the cam lode off. NASCAR runs flat tappets and has squinters on the lobe
 
Spoke with Mike at Harland Sharp today. They have a few sets of roller rockers available for 24 valves as we speak. Use bushings instead of bearings. They felt with the oil system on these trucks it may allow much more oil to flow thru the bearings affecting overall oil pressure so they stuck with bushings. Regardless, testing has shown they work great on pulling trucks and racing trucks, however don't last very long on street driven trucks. After 3500 miles, they saw enough wear in the bushing to have to maintenance the rockers...

Stock ratio's available now, custom ratio's available if your request them. He can make you a deal on some, but for a reference point, retail price is $2100.

With that said, Greg when can you ship me some stock replacements?
 
The best part of Harland Sharps is they look BEAUTIFUL!!

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COMP461 said:
If I was going to do anything it would be to install a 60mm cam with the thinner roller. I would never install a roller lifter in a Cummins, the lobe profile with a 1.5 tappet is incredible, and cannot be duplicated with a roller lifter. This is a mathematical fact. The only reason for a roller lifter is extreme RPM’s as in Super Stock Tractor engines that turn 7500 rpms and the necessary spring pressure needed to do this would wipe the cam lode off. NASCAR runs flat tappets and has squinters on the lobe
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I'm just trying to discuss because I enjoy the discussion so don't take the following questions as being offensive

Why I understand a the 1.5" tappet does allow for more aggressive lift in a flat tappet application vs. the smaller diameter flat tappets (Chrysler really figured this out back in the day with their massive at the time .903" diameter flat tappets), I still fail to see the flat tappet allowing for more aggressive lobe profiles at any rpms vs. that of a roller. I believe the cummins flat tappet cams are just like gas motor flat tappet cams, that is the lobes have a taper to them which is higher toward the back of the motor and lower to the front of the motor. This keeps the cam in the block and aids in rotation of the lifter. This is why a cam button is needed when swapping to a roller cam in gas motor apps because if not the cam will walk out because it has no taper. This being said if this taper exists it may serve to further reduce the contact area from tappet to cam lobe, far more then a roller tappet, which will reduce the amount of aggressiveness that can be built in the lobe. You say however that it's a mathematical fact that the 1.5" tappet allows for more aggressiveness in the cam lobe. Would you care to share some mathematical facts such as diesel lobe duration at .006", .050", .200"? If you can't share for industry standard reasons I understand. I'd like to find a similar at .050" roller lobe to compare which is the reason for the request.

NASCAR runs flat cams because the rules indicate they have to, they don't run them because they are advantageous. Further, the flat tappet cams they run are made of unobtanium type materials that would quadruple the cost of most roller cams (why making less power to boot) to deal with the requirements of the rules, high lift, high rpms, and endurance. Also, like you indicated, they have to run all kinds of oiling modifications for these flat tappet lifters to survive in these applications.

Just axing cause I’m interested
 
Nick back to drawing the picture. The roller cam has to have a more aggressive lift to get the same valve action as the flat tappet. I am not saying which is better or not. Just saying that the roller cam needs to have the more aggressive profile to get the valve to open at the same rate of the flat tappet. Think of tangent lines and all when your thinking of the roller, maybe that will help.
 
zstroken said:
Nick back to drawing the picture. The roller cam has to have a more aggressive lift to get the same valve action as the flat tappet. I am not saying which is better or not. Just saying that the roller cam needs to have the more aggressive profile to get the valve to open at the same rate of the flat tappet. Think of tangent lines and all when your thinking of the roller, maybe that will help.
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Dan, I don't agree with this. A roller cam of same duration at .050" almost always makes more power then a flat tappet cam. Why? Because the roller cam moves the valves faster everywhere in the lift range. Ofcourse this is contigent upon no valve train harmonics being introduced by the roller cam, pushrod deflection, etc.

I understand what you're getting at I just don't agree with that fact that it's happening. How could a flat tappet translate motion fo the valve any faster then a roller tappet? Unless the roller tappet is moving around (in which you'd likely see failure quickly) it's not possible unless i'm missing something.

Lets just say I politely disagree:Cheer:
 
I am not saying that a flat tappet cam can in the all out effort can out do a roller cam. I am saying that given the same grind on the cam, the flat tappet valve will open and close faster. Or if you want the valve motion to be the same the roller cam will need to have a more aggressive ramp(or a roller with a 10 ft diameter)
 
zstroken said:
I am not saying that a flat tappet cam can in the all out effort can out do a roller cam. I am saying that given the same grind on the cam, the flat tappet valve will open and close faster. Or if you want the valve motion to be the same the roller cam will need to have a more aggressive ramp(or a roller with a 10 ft diameter)
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I still don't follow, seems a physical impossibility. The face of the flat tappet follows the cam lobe, the face of the roller wheel follows the cam lobe and that's it. How can either transmit the cam lobe shape differently?

The contact area of the roller lifter is quite a bit more as the entire width of the roller wheel rides the lobe (width being one end of the roller wheel shaft to the other end of the roller wheel shaft). The flat tappet lifter only contacts a very small portion of the cam lobe as it's round and the cam lobe is tapered further reducing the contact area so far as I understand it.

Increasing the diameter of the roller tappet wheel would only surve to provide a gentler radius in the face of the roller tappet allowing for a more agressive lobe. Given the same cam lobe and a larger or smaller diameter roller wheel, I fail to see how the larger diameter roller wheel transmits anything differently then the smaller diameter roller wheel. :what:

I've certainly been wrong before though and this could be one of those times!
 
Maybe I am explaining it wrong and maybe I am not thinking it through correctly.
 
Ok, I definitely screwed the pooch on this one! Dan, you were right and comp dude you were too! I just wasn't thinking of the flat tappet trapped in the bore and the way the leading edge would strike the opening ramp, the mid point hitting the centerline, and the following edge traveling down the closing ramp. Like I said, wasn't the first time I was wrong lol!:p
 
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