Aggressive/Extreme cams?

Discussion in 'Street/strip 400/430/455' started by Rodney Byrd, Sep 12, 2009.

  1. stage2man

    stage2man Well-Known Member

    Scott Brown cams do not have this problem! Used your same cam in my '71 which liked to shift right at 6,000 and in another local guys stage1. Both cars sounded great. This cam is well known as the big car performance cam for it's huge torque figures. Scott's cams are asymetrical profiles, fast open, easy close. The mopar profiles seem to run great in the 455.
  2. James McD

    James McD Well-Known Member


    Thanks, I thought as much but I wasn't sure. The noise isn't that bad, but I can hear it.

    You shifted at 6,000? My car feels all done by 5,500..(or maybe a bit less). I currently have cast iron intake / exhaust manifolds, they probably put the squeeze on things.

    Thanks again for your input.

  3. leo455

    leo455 LAB MAN

    General question? Would or does ford fe lobe designs work in a BBB?
  4. Rodney Byrd

    Rodney Byrd Torque

    True MoPar lobes will not work in any GM engine unless the LIFTER is changed/block modified to the .904" MoPar size. The lobe will destroy itself against a .842" GM sized lifter. A GM or Ford (.875") lobe will work with a .904" lifter, but not the other way around. I believe NASCAR uses .875" tappets in everything, but the .904" does give an advantage, unless a bigger (.960 or 1") mushroom lifter is used. A .904+" mushroom lifter could be used with a MoPar lobe in a Buick, I guess... RB
  5. Rodney Byrd

    Rodney Byrd Torque

    NO, they are for a .875" lifter, see above post about MoPar lobes in a Buick... RB
  6. Rodney Byrd

    Rodney Byrd Torque

    Have a small VooDoo cam (256deg) in a very mild 360 MoPar in my '74 DartSport (Duster!). Very happy with it, and it is specific to the larger .904" tappet that AMC and Chryslers use.:TU: No strange noises or problems so far! I like Lunati cams, and considered the Hemi killer series (230/240/113LSA/.501") for this BBB build. Had the old TorqueTech SP235 in my Regal back in the '90s, and loved it, but it was a little much for this setup (maybe with Rhoades lifters, Hmmmmm!:Brow:)...
  7. Cali72's

    Cali72's Well-Known Member

    How did that thumpr hybrid work?
  8. 70 gsconvt

    70 gsconvt Silver Level contributor

    Wow. Just found this thread.

    I'm getting ready to order a custom cam for my 455 rebuild. I was going to call Scott Brown. Is there someone better out there for the job?
  9. Bad Buick

    Bad Buick Foe Fiddy Five

    What does your TC stall at? Compression ratio?
  10. 70 gsconvt

    70 gsconvt Silver Level contributor

    Torque converter is a 2800 stall, compression will be right at 10.5 to 1.
  11. BuickAl

    BuickAl Well-Known Member

    Ok. This is an old post, but I have a question about fast ramp cams. If my understanding Is correct that the angle of the lobe on a fast ramp cam is steeper than a non fast ramp cam, wouldn't the cam lobe more directly contact the edge of the lifter, which I would t think is a good thing as the edges are sharper?

    Sorry if my lack of knowledge has resulted in my asking a really dumb question.

    Sent from my iPhone using Tapatalk
  12. gmcgruther

    gmcgruther Well-Known Member

    I can't understand the Pontiac thing, look at the engine builder for Justin Shear ( The Crow) now CrowMod. Rodney Butler blew that theory out the window. Cam cores? There is plenty for Big block Buick's. I can call LSM Systems Engineering in Waterford,Michigan and get one any time I want and they custom grind cams to your ride too.
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The answer to your question is in the very first post of this thread. The flat tappet lifter can't keep up, and the engine loses control of the valve train. The term used was "lifter crash".

    If you read this thread, Jim Weise tests 3 cams in the same dyno session, one of them being a Lunati fast ramp cam. See what happens (go to post # 20)
  14. sailbrd

    sailbrd Well-Known Member

    Phillip, go with Scott. I went with one of his solid flat tappet cams that Finishline speced for me. It is quieter than my 413 hydraulic and I don't know what it will rev to because I don't think I should go there. Right now I have the shift light @ 5800 and the rev limiter at 6200.
  15. BuickAl

    BuickAl Well-Known Member

    Larry. So the issue is with flat tappet cams.....and the answer is a roller?

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  16. Bluzilla

    Bluzilla a.k.a. "THE DOCTOR"

    Interesting old thread! Like Cliff said, "there is always someone who runs good with this stuff". I have a XE274 in my small block '70 Corvette and love it. It's quiet, pulls strong from idle through 6000rpm. Just finished a build for a customers '67 396 Chevelle with that cam...same results. I like it so much that I installed one in my '68 Tri-Carb 427 Corvette Roadster, but haven't finished that restoration yet. It's too bad the Pontiac and Buicks are not sharing the same results as the Chevys, but after reading the thread I can understand why.

  17. Buickrat1

    Buickrat1 Well-Known Member

    I have been Extremely successful running fast ramp cams. I run a lot of Bullett Racing cams which is the company that purchased Ultra Dyne masters. I run a lot of .550/.560 lift Hydraulic flat tappet cams with 228/240 duration at .050 I to ran into the so called "lifter crash" more like unstable valve train issue with the fast ramp cams. I ran into a Super stock engine builder who told me to run a Beehive valve spring made by PAC springs and it would cure my problem. He was right! I purchased a set of PAC 1218X single springs, retainers and locks for 11/32 valves and it cured the problem. The spring,retainer and lock combo reduced my valve spring weight by 40% The engine now pulls strong to 6200. The combo also fixes any retainer to rocker arm clearance issues that bigger valve springs can cause. For the Roller cam guys PAC also builds some 1.280" - 1.320" diameter Dual valve springs that also save valve train weight, these springs work very will. Anyone interested in purchasing these springs, retainers and locks can purchase them from TA Performance. The are more costly than the standard spring combos that most Buick guys purchase but well worth every penny.
  18. pmuller9

    pmuller9 Well-Known Member

    Good question. You are correct. The lifter edge should not contact the cam lobe.
    The lobe intensity or lift rate of a flat tappet cam is limited by the lifter diameter.
    You will see some cam companies list their cam profiles by lifter size.

    In cases where roller cams were not permitted a mushroom lifter was used.
    Last edited: Apr 27, 2016
  19. BuickAl

    BuickAl Well-Known Member

    Mushroom lifters......interesting and the first I've heard of and seen them.

    So your comment about lift rate suggests to me that the bigger the diameter of the lifter, the greater the lift rate can be? Conversely, smaller lifter diameter means less left rate is acceptable. I assume roller cam setups by their nature don't have this limitation.

    Sent from my iPhone using Tapatalk
  20. pmuller9

    pmuller9 Well-Known Member

    Yes, that is correct.
    When you look through a Cam Lobe Master catalog, each flat tappet lobe specifies the minimum diameter lifter to be used. Here is Comps lobe master catalog. Have a look.

    The same actually holds true for the roller lifter.
    There comes a point where the minimum roller diameter is specified and the lifter diameters have to be larger to fit the larger wheel.
    You don't usually see this until you get to the bigger solid roller cams.

    A .842" roller lifter has a .750" wheel.
    We use a .936" diameter solid roller lifter with a .850" wheel.
    Then there are roller lifters with over 1" diameter bodies using .900" wheel diameters and over.

    The classes that restricted the cams to flat tappet only eventually restricted the body diameter making mushroom lifters illegal.


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