[Scott Misus]

Hmmmm.

Half Inch Stud runs 12.0. QJet, 12 year old Lunati FLAT hydraulic cam, factory rods, TR-trouble-U pistons, iron heads, 455, 12 year old convertor, self-built Th400, 3.31 12 boat. Driven daily. PA inspected.

[Steve C.]

HIS- you mention busted lifter bores, probably a real fluke with a hydraulic roller. In all likleyhood the hyd's ramps won't be that aggressive.
When comparing the two types I think the effort should be made to match the duration at .050" at let it fly, the hyd roller should have more duration at .200" which would be typical and as Skip mentioned the advertised duration might come in at slightly less duration. These are some of the advantages.

[This message has been edited by Steve Coombes (edited 10-22-2001).]

[Half-Inch Stud]

JSchmitz, FFCC,

Clearly my last post was pure drivel. Hope you[z] can appreciate my 2cents for grasping at the obvious.

Misus, 500plus had the motor potential, yet needs to get the chassis up to the motor capability.

I too have the motor/trans capability way outpacing the chassis Inspection capability. Going from 12.0 to low 10's or high 9's is realistic powerwise. A common, recurring problem these days. Blower stays off until I can pass tech with it on. Cage, 5-point seatbelt, sneeze belt, SFI-Flexplate, and a rear that can take the twist. SFI-Balancer can be faked with timing tape. [img]/infopop/emoticons/icon_smile.gif[/img]

Apparently, we have arrived at exceeding our powerplant requirements from different directions. Only in the measure of economic efficiency does my powerplant look superior. Otherwise, pop my hood and see stock - hardly interesting to the rest of the board. Maybe the Hands, and some select others. My use of the Q-Jet&HEI is like having the Clash open at a Who concert. Poor taste, pointless these days, and rather dated.

We'all in the Racing Section are way too power-conscious when the begging issue is really Inspection compliant chassis to allow the runs. Full-Interior stuff.

E-head vs D-Head is a joke topic from my perspective. Flay vs Roller expounds on the same joke. PowerGlide vs TH400 or other would be the next joke to open.

We need a chasseur to lead a Steet/Strip 9.90 compliant chassis topic!

------------------
"11.00/123MPH 29.5"/4.10:1/10"/472 #48/DualQuad/3250Lbs
12.00/112MPH/26"/3.31:1/10"/472 #48/Q-Jet/3650Lbs"

[Half-Inch Stud]

Steve Coombes,

Hmmm, I have always been under the impression [illusion?] that a Roller cam shows about 25degrees more numerical duration to equate to an agressive Hydraulic, when both are LIMITED TO .550" VALVE Lift. Example:

FLat HYD : 255/255 at .050" Valve checking.
Roller HYD: 280/280 at .050" Valve checking.
Aggressive Cam lobe profiles normalized to Valve lift profiles, peaked at .550" lift. .550" valve lift picked by me as the arbitrary "safe limit" for long-life springs in traffic overheat and Street/Strip applications. Street/Strip is always ready for raceday.

Look closely and carefully at this play in numbers before laughing hard out-loud. At first, a Roller looks like it Lifts the valve fast and hard. But the Flat HYD already lifted the valve. Upon peak lift the Roller my not dwell the valve any longer that the Flat HYD - That's why the .300" lift number separate the men from the boyz. I choose to stay with FLat HYD after inspecting the >.300"lift numbers of Roller to HYD as comperable for 25degree differences at .050".

Maximally-lifted Valve-open time is the Area under the curve, a worthy parameter to optimize. Should result in Broadband Torque and decent HP ramp, the other area under the other curve.

Time for lunch, at risk of talking out my a$$ without my notes at hand. Luckly, it all seems clear..Could be mistaken, but that's what I tink.

[GTO Karl]

I like the Clash and the Who...I'd go to that concert. Afterall, the Who were considered by many to be the first "Punks". And I'm an old "punk rocker", skateboarder. Built my first half pipe in 1977.

The main problem with Hyd. rollers, isn't that you couldn't find a grind that would have more "area under the curve" than some other flat hyd. grind. It is that most don't have enough more to justify the cost. And from what I have seen, most people that show up at the track with hyd. rollers, have chosen cams so small, they could have made more power with any cam had it been a better choice.

But this is a problem with who is selling the cams, not the cams themselves.

Karl

[Steve C.]

I made a correction to my post above... I ment to say the hyd roller should have more duration at .200" lift. As Skip mentioned looking at a cams duration at .200" will give you an indication how agressive the profile is and the rollar lifter will allow a more agressive profile. On the subject of lifter bore problems, for the most part it's the very aggressive cams that cause the problem. It's my understanding that you have to have a cam with duration approaching 200 degrees at this .200" lift to become a issue. A 'agressive' hydraulic rollar will never get there, for example a hyd roller with 262@.50" might have 170 to 176 degrees duration at .200" lift. In comparision a similar 262 SOLID rollar will probably have over 180 degrees duration at .200" lift.

[Half-Inch Stud]

GTO Karl, I'm there man.

Steve Combes,

Oh, then I retract my technical chapter above, and agree with ya !) Naw, I'll stick to my gauntleted guns.

Last I recall, in 1991, the UltraDyne lobes "D" and "E" were not recommended for Street/Strip because they were too aggressive. Well, naturally, I made a cam with D lobe intake, and E-lobe Exhaust..against Jim Butler's advice.
Jim said "you watch it there boy, you'll likely be busting your springs from too much valve acceleration. I got a boy down the street...". Sure enough, I busted several inner springs after 500miles of "YeeeeHaaaa!" driving to work. Upon in-situ valvespring upgrading, the cam/springs have held-up to overheats and 1/4mile activity. The highly aggressive roller lobes at the time were considered equally aggressive at the valve. Kind of moot.

So, you;d be right to checking the .050", .200", .300", .400", .500", .550" [pretty much maps-out the lobe] to say "see the Roller is different". Yet, for conversational purposes [Isky pleaded these standards, rather than the meaningless .007 checking standard] We'all are accustomed to Durations at .050" Valve checking, but assumed Flat solid or HYD. We'all need to inspect .050" and .300" to measure-up the Equivalent Roller grind, with the same peak valve lift.

Otherwise, we're lost in Babylonia.

H.I. Stud

[Half-Inch Stud]

Clarify: Isky pleaded for the .050" checking Standard for Flat Solid/HYD cam to be included with the .002-.007" Advertised Duration practice. The tightly-knit cam-cutting and distribution community agreed.

But we'all knew that.

H.I.

[Steve C.]

HI- Can't find any referance to D&E lobes in my Ultradyne catalog (old). Curious as to the duration at .200" valve lift on those grinds considered aggressive (I can only relate to .200" lift since it's in the catalogs). The 200 at .200" figure I touted is only here say, its just been floating around and I don't know where it came from. Those I've talked with that busted lifter bores had race motors with big cams.
We ran a UD solid roller with 182I/188E @.200" for years and I have buddies that commenly run cams around 170I to 180E @.200" with no lifter bore issues.

[Half-Inch Stud]

Sorry 'bout dat.
UD Flat HYD Back in the day...

Lobe Designation A B C D E
Advertized Duration 288 296 304 312 320
Duration at .050" 231 239 247 255 263
Duration at .200" 143 151 161 166 176
"Overlap"............51..53..67..75..83
Valve Lift w/ 1.5:1.487.507.530.551.556"

Case in point: The UltraDyne Roller 268/268 at .050" is a 304/304 at .020"checking! An apparently small Advertized Duration.

Quiz: What kind of Advertized Duration does this Roller have at .002" ?
How about .007" ?
Do we care? no unless we want to relate the valve events to the Flat cam ADV numbers [ a comfort zone]. Intake Vacuum Signal may care upon Intake cracking open and Intake Closing though.

Note: The advent of Flat HYD Lobes with .050" Durations from 245deg to 263deg represents an area previously occupied by Solid Rollers [when I was a baby]. Takes about 20 years for new idea to be considered typical.

Note: More duration than 263 at .050 usually forces the lobe to have MORE valve lift than .556". The penalty is alobe ramp with acceleration forces follwed by deceleration forces causing Lifter bounce, Valve bounce, etc. Time to go Roller if the owner thinks the power will be there.

did this help.......H.I. Stud

[BVR421]

""""Clarify: Isky pleaded for the .050" checking Standard for Flat Solid/HYD cam to be included with the .002-.007" Advertised Duration practice. The tightly-knit cam-cutting and distribution community agreed."""

I dont think that sounds right, 050 specs are not the ISKY way. Certainly not with a 5 cycle cam......
Do ISKY catalogs or cam cards have 050 specs? I dont know, I havent seen one for 20 yrs.


OK, Im convinced a HYRoller is the way to an incredible power increase for my street 421. Lets see, I'll replace my $80 SUMMIT cam (744 clone) and lifter kit with a same spec HYROller at $600 something. But wait, are my valve springs that work so well with my present cam going to be OK or will I have to shovel out a couple more big ones? Maybe get the cam swap project to come in under a grand if I do the labor?

[Bermuda Blue]

About a year ago Car Craft had an article comparing cams with different ramp rates. They used a Mopar engine since Mopars have a larger lifter diameter than our Pontiacs and can therefore use a wider variety of cam profiles. The lift rate of a flat tappet is limited by its diameter.

They used 3 different cams with identical (or very close) 0.050 specs. Nothing was changed during these comparisons except the cam. The more aggressive cams where able to achieve a higher lift due to their higher acceleration and deceleration rates when compared to the baseline cam.

The bottom line is that all cams had similar idle characteristics and the more aggresive the cam profile the more power was made. I think the most aggressive cam made 35 more HP than the baseline cam. If someone would like more info on this article I can email them or post it.

All this really tells is that its better to open the valve faster, hold it open longer and close it faster. I think we already knew that.

The real debate here is how much better (if at all) is a flat tappet cam than a hyd. roller given the grinds available to us? And is the hyd. roller worth the extra cost?. I have access to a cam profiler and plan to compare the two cam types to see how much more "area is under the curve" with the hyd. roller. This experiment hinges on wether I have the time and money to do it. I plan on build a motor next year and money is tight right now so this experiment won't happen anytime soon. Maybe in March.

[Skip Fix]

Be neat to see how much extra area is there.

One thing to look at is actual specs. Comps new Xtreme hydraulic flat tappet lobes actually have an "advertized" seat duration less than their hydraulic rollers with the same 0.050 duration . In degreeing in my own 262/270 seat duration Xtreme energy h. flat tappet using Comps 0.006 tappet lift was actiually a 270/278 seat duration, 0.050 was right on. I think they have figured out we are more informed buyer now and expect smaller seat durations for "aggressive" lobes they are advertising. They might be fudging a little if they are all like my cam