Reliability of Lobes Designed for .904 Flat Tappet Lifters

[gtxrt]

i would think some what the wider the lifter less pressure just like wearing a wider heel on a shoe then a smaller pointed one. i would say an engine with bigger cam journals and the longer the cam lobes could be making it less pointed and faster smoother ramp and less wear.

 

[rikkitik]

Tim @ Bullet is an outstanding resource, as is Mr Porter (PRH). I have learned a lot from Tim (and Dwayne), and have never been disappointed in Tim's cam selection (35 years worth).
Maybe I have learned a bit along the way though. With my current cam, I told Tim what I had and what I wanted. Tim laughed and said, "close, what I'm going to suggest is only a degree or two different".
Tim was with Ultradyne (Harold Brookshire), then moved to Bullet when they bought/opened the business. Bullet has the Ultradyne lobes available as well.
Harold designed Lunati's Voodoo (not all of VooDoo though) series after he lost/sold Ultradyne.
Currently running an Ultradyne pattern SFT, with (.904 asymmetric) lobes. VERY happy with it. I've always run .904 lobes on .904 lifters, never had an issue. Currently @140# seat, 365# over the nose, VR1 20/50.
No issues with "not coming on early enough" either. Just a "little" 440 +.030, but it blows the tires off just past 1/2 throttle in first at 2300rpm (4spd, 3.54's) 295 T/A's ......(M/T's are coming).
Also, (I'm fairly certain) Hughes has Howards grind their cams. Howards lobe list pretty much matches Hughes profiles. Hughes can actually be fairly indignant if you ask for "advertised" duration, I was told "advertised means nothing!".
Uh, yes it does.....
You cannot build cylinder pressure until the intake valve is CLOSED, and on the seat. The advertised to .050 numbers are very useful information for closing point.
Hughes does seem to have the most aggressive FT, lift vs duration numbers.

 

[66Satellite47]

i would think some what the wider the lifter less pressure just like wearing a wider heel on a shoe then a smaller pointed one. i would say an engine with bigger cam journals and the longer the cam lobes could be making it less pointed and faster smoother ramp and less wear.

Not a good analogy but think what you want. The advantage of the larger lifter is it allows a more rate of lift to be designed into the lobe. My mushroom lifters are about .990. They can produce the rate of lift that solid roller cams did back in the day. In the '60's NASCAR didn't allow roller cams, the solution was the mushroom cam. Bigger lifter face allows for a faster rate of lift. A wider lifter can start the valve actuation sooner and continue it longer. It's not a wear issue.
EDIT: I should have emphasized ALLOW a faster rate.

 

[Curiousyellow71]

If the opp is seriously considering a xe275hl buy a lifter from hylift Johnson instead of comps lifters. At least stay away from the lower end lifters from comp. Comp cams does sell some more expensive lifters...and they possibly could be hylift Johnsons reboxed but... I have never been able to verify where they are made, and comp operates by their bottom line. They will not say where they are made and they can source them from where ever they choose that appeals to their "bottom line". So I am not against comp products...but it can be a roll of the dice. Typically the lifters that come in a kit are not good.
A good portion of the flat tappet cam cores are made by cwc in Michigan. If you look on the cam it will have cwc right on it. Companies like Comp cams, crower, lunati or bullet "usually" use a cwc core and are just grinding the cam itself. Comp though...you never know where they get parts. The last comp 284xe we bought had cwc cast right on it. Same way with the last crower and bullet we bought the last couple years. As far as durability I am not all that hopefully of getting lots of miles out of comp cams XE series. The last XE w high energy lifters that we pulled start showing some wear on the closing side of the intake at 8000 miles. The opening side of a XE is not really that much different then other fast rate brands. The closing side drops the valve quicker then a lunati voodoo or ultradyne.

On another note... The biggest ultradyne .904 profile we have is 255/[email protected] .582/.598. I would not have the expectation to drive it 50,000 miles but it isn't far off from a roller cam. It's incredibly aggressive. But it's not in the car yet. We have done a bunch of the hydraulic and flat tappet ultradyne cams in pontiacs. Great cams.
As far as hp gains from less friction from a roller cam it doesn't seem 2 make much of any difference. Just more area under the curve and they survive big spring pressure, where a flat tappet would be short lived.

 

[beanhead]

The advantage of the larger lifter is it allows a more rate of lift to be designed into the lobe.

Yes. Being a .904 design doesn't automatically mean a given cam is more aggressive or 'fast rate', but it has the potential to be. Plenty of .904 cams had laaazy lobes and used soft springs. All depends on the grind.

 

[Rich H.]

A good portion of the flat tappet cam cores are made by cwc in Michigan. If you look on the cam it will have cwc right on it. Companies like Comp cams, crower, lunati or bullet "usually" use a cwc core and are just grinding the cam itself. Comp though...you never know where they get parts. The last comp 284xe we bought had cwc cast right on it. Same way with the last crower and bullet we bought the last couple years.

The casting does indeed appear as "CWC", but the foundry mark is a mirror image of the company name CMC, Camshaft Machine company.

Camshaft Machine Company

In addition to core production for almost every cam company out there, their business also includes finish grinding and in that regard they are the supplier for the MP Purple Shaft product line.

 

[Dodge Bros]

CWC and CMC are different companies. It gets confusing because basically all the cams CMC grinds are supplied by CWC. CWC is the main supplier of all the flat tappet cam cores here in the US.

CWC is a foundry that supplies cam cores. CWC Textron Castings

CMC grinds cams

Camshaft Machine Company

 

[Dodge Bros]

That oil PR linked, Driven,was developed by the Joe Gibbs NASCAR team for flat tappet cams back in the late 90s when the oils had a lot of changes done that adversely effected durability of flat tappets. IRC at that time they were loosing 1 out of 10 engines on the dyno from flat tappet failures (nascar at the time ran all flat tappets). If your serious about running a good flat tappet oil, it is definitely worth looking at.

How aggressive you get with a flat tappets depends quite a bit on how much life you expect out of it. The Mopar performance HFT grinds were .904 specific had more duration at .2” lift than something similar in a .842” tappet grinds, and didn’t require a ton of spring pressure, less than a lot of modern grinds. We use to turn 6000 rpm with stock magnum springs with those purple cams. If a lobe goes flat with one of them you where likely going to loose that lobe no matter what profile it was.

The compcams purple plus is a .904 lifter grind and is suppose to be direct replacements for the old MP grinds, and have similar lift and duration at .050” , and .2” to the Mopar performance grind they are suppose to copy. But they are a lot more aggressive off the valve seats and require quite a bit more spring pressure. It will likely not last as long as an old MP grind, but I think it would last as long or longer than a XE comp grind which is designed originally for a .842” lifter.

The Lunati Voodoo have similar profile acceleration to the purple plus grinds but have a lot more lift.

Howards have more seat timing like the old Mopar performance grinds, with lift maximized for the lifter, and don’t require a ton of spring pressure, either. But the extra lift can create quite a bit of pressure over the nose with to much spring rate.

The hi lift 904 comp HFT versions are both aggressive off the seat and have a lot of lift and require more spring rate yet than any of those other cams.

If you really want to step it up, and run an aggressive 904 design, Bullet, Howards, and Comp have solid flat tappet 904 lifter grinds that makes a compcams Hi lift XE hft’s look wimpy. But solid lifters add the option of EDM oiling that pressure forces oil direct to the lifter face, and often are ground from a tougher cam core. When you start pushing lift much past .5”, your better off going that direction.

 

[Rich H.]

CWC and CMC are different companies. It gets confusing because basically all the cams CMC grinds are supplied by CWC. CWC is the main supplier of all the flat tappet cam cores here in the US.

CWC is a foundry that supplies cam cores. CWC Textron Castings

CMC grinds cams

Camshaft Machine Company

Thank you for clearing that up!

 

[JedIEG]

Thanks for the replies. Experience with the different cam grinders and lobe reliability is great to hear and what I was hoping to get from this thread.

I am fairly well versed in the theory behind designing a lobe to utilize the .904 lifter. I just find it interesting that all the companies came up with wildly different max lifts for lobes of similar duration. Without seeing a full lift schedule or at least a advertised, .050 and .200 durations it's really hard to tell what their design goals were. I probably should just do the math and see what lobe comes out closest to the calculations.

I am starting to wonder how the reliability and performance of a .842 lobe with a 1.6 rocker stacks up to a .904 with a 1.5 rocker. From a cost perspective, it seems like a better package since you could get a lower quality lifter with the less aggressive cam and spend the money on higher quality rockers and move more of the system stress into the rockers. Lifters seem to be the weak link usually... once again, I probably need to bite the bullet and just do the math on what the stresses are for those options.

 

[66Satellite47]

The combination of duration and lift is what gives it's performance characteristics. Lift seems to relate mostly to the heads flow capability. I may be wrong.

 

[Curiousyellow71]

I wouldn't suggest going the lower quality lifter route. It's just not worth it unless it is a stock grocery getter. Cam goes bad because of a poor lifter and trashes the whole engine.
Going with big lifts and higher ratio rocker arms are a waste if you don't have the head flow to support it. You can actually go slower if the head flow goes turbulent. Fairly common for stock heads to be done at .5 lift when we flow them on our bench.