Comp Cams offering Nailhead Thumpr

Discussion in ''Da Nailhead' started by CameoInvicta, Nov 30, 2009.

  1. wkillgs

    wkillgs Gold Level Contributor

    Okay, let's put it this way.... a lumpy idle is generally a result of more valve overlap.... Which can be obtained by close lobe separation, or adding lots of duration. :grin:

    Looking at the cam specs I have on file, valve overlap varies from -19 for the '66 stocker, to +36 for Comps' 'Big Mutha Thumpa'!
    My Isky 310 is at +28, the TA 413 at +13. My Isky has a nasty idle.:laugh:

    For decent low-end power, an Accelerated Motion 223-234-110 has +8.5 degrees of overlap for a lumpy idle. Might be a good choice for Steve. Take a look Andy, I believe this one was on your list.
  2. CameoInvicta

    CameoInvicta Well-Known Member

    True, I know the TA-413 has a pretty decent idle, but it's spec'ed at a pretty wide LSA. I think it has 15* of overlap.

    Your correct, that was on my list, I had actually forgetten about that cam. It's a shame the company is going to be down until April.
  3. RipRohring

    RipRohring 53 SUPER V8 12 Volt

    :Comp: Me, having absolutely ZERO cam experience, know that I would LOVE to have a "lumpy idle" on my 322 ci Nailhead. That being said, has anyone out there taken a 322 and added a cam of any kind ? Any cost estimates to achieve lumpy status in a 322 ?

    I really have little to NO desire to run hard thru any quarter miles at the track, and I don't want to erase any crosswalks leaving elementary school intersections either.Perhaps I'd like to blow off a Corvair or a Puegot at the County Fair parking lot races.

    Rip Rohring :Comp: All I wanna do is "sound cool" :idea2:
  4. doc

    doc Well-Known Member

    in the old days to get a ''cam'' sound we would run one idle screw in and the other out to make the ingine lope....:Brow: :Brow: cheap trick.....:Brow: :Brow:
  5. tmcclu

    tmcclu Well-Known Member

    The 322 guru is Russ Martin, goes by "Buickrodder" on ebay. He knows what to put into the lil' nails to make them do what you want and usually has the parts in stock to make it happen.
  6. Mr62Buick

    Mr62Buick Guest

    Well, having the switch pitch trans in my 62' helps the lopiness greatly... so much for needing low end torque... he he he... anyways, what kind of weights do I need for the timing to be set perfect for the factory dual quads. I have way too much weight on the car and get too much traction with the posi... so, how do i dial in the distributor? The engine runs great, but I wanna roast the shi- out of the tires in front of the cheby, turd and mo-parts guys.
  7. wkillgs

    wkillgs Gold Level Contributor

    Install some lighter springs from an advance curve kit. If you go too light, the engine might ping due to too much timing too soon. You have to experiment to see what works best.
  8. wkillgs

    wkillgs Gold Level Contributor

    The graph shows HP as 'Power'.....there is also an option for 'Indicated Power'.
    That will increase the hp figure about 50 hp and give a hp reading close to Buick ratings.
    Any idea what 'Indicated HP' is?

    Try this:
    right click on graph. for Y2 data, select 'Indicated power'.
  9. CameoInvicta

    CameoInvicta Well-Known Member

    I think I read that "Indicated HP" is the horse power rating without the frictional losses inside the motor. So it's just a theoretical number - there is no way to acheive that in the real world.
  10. wkillgs

    wkillgs Gold Level Contributor

    Thanks. At least it would remain constant regardless of the other engine parameters (except for roller cams). It could be used as the 'correction' factor we talked about.
  11. Babeola

    Babeola Well-Known Member

    Walt ,

    I found this definition:

    "Indicated horsepower (ihp) is the theoretical power of a reciprocating engine if it is completely frictionless in converting the expanding gas energy (piston pressure × displacement) in the cylinders. It is calculated from the pressures developed in the cylinders, measured by a device called an engine indicator—hence indicated horsepower. As the piston advances throughout its stroke, the pressure against the piston generally decreases, and the indicator device usually generates a graph of pressure vs stroke within the working cylinder. From this graph the amount of work performed during the piston stroke may be calculated. It was the figure normally used for steam engines in the 19th century but is misleading because the mechanical efficiency of an engine means that the actual power output may only be 70% to 90% of the indicated horsepower."

    Cheryl :)
  12. wkillgs

    wkillgs Gold Level Contributor

    So Andy, what cam did you end up using???:Brow:
  13. CameoInvicta

    CameoInvicta Well-Known Member

    Walt, unfortunately I left the stocker in there. Doing everything else that needed to be done sucked up all of my budget. It's not even totally done, although it's close, and I'm already in the red :laugh: .

    At some point, probably about 4 years down the road, the heads will get ported and I'll probably install a custom hydraulic roller.
  14. CameoInvicta

    CameoInvicta Well-Known Member

    Ok, just to add something interesting to the whole valve-piston clearence issue debate. Check out the YouTube video below...

    <iframe title="YouTube video player" width="480" height="390" src="" frameborder="0" allowfullscreen></iframe>

    I accidentially found this video over the weekend. I sent the guy a message, and he stated he tossed in the normal Thumpr cam w/o any other modifications. I thought that was interesting, since we more or less concluded that it wouldn't fit w/o having valve-piston clearence issues.

    Anyways, thought I'd share. Maybe we can fit a bigger cam than previously thought?
  15. gsgtx

    gsgtx Silver Level contributor

    nice post, cool video
  16. Wicked50

    Wicked50 Well-Known Member

    i like the video too bad he didnt rev it.
  17. wkillgs

    wkillgs Gold Level Contributor

    Interesting. I wonder if he even checked vp clearance?
  18. CameoInvicta

    CameoInvicta Well-Known Member

    I would assume no. He said he just put in the cam along with new lifters.
  19. Babeola

    Babeola Well-Known Member

    Tom has been telling us for years that the stock rockers lose ratio as the lift increases. That was the probably the stroke of dumb luck needed to run it.

    Cheryl :)
  20. TAANK

    TAANK Well-Known Member

    Pistons allready had valve reliefs?

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