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400 sbc cam swap.... help on choosing a cam ?

Discussion in 'The Hokey Ass Message Board' started by awsomeears, Jun 5, 2013.

  1. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    To convert the stock cam for 1.6 rockers divide 1.6/1.5 and multiply that times the stock lift spec.

    1.0667 * .390 = .416
    1.0667 * .410 = .437

    Divide the valve lift / rocker ratio to get the lobe lift.

    Your .430 / 1.6 = .269 lobe lift .450 / 1.6 = .281.

    The Voodoo cam would be very similar to the XE 274 just 3 degrees less @ .050 , but on Camquest 230 seemed to be the magic number. Of course that's a simulation, I doubt you could tell the difference.

    The ISKY 280H is a bit out of the RPM range the OP spec'd.


    I really don't know who has done more to advance the art of camshats than Scooter Brothers and Comp since the 80's, but that's opinion.

    Hoop
     
  2. davidh73750
    Joined: Apr 21, 2009
    Posts: 1,536

    davidh73750
    Member

    this wk end I really paid attention to my tach in my 55 mordor with a 400, watched the rpm range. Drove it in town, I drove it over 100 mi hwy, got a 200r, 400sbc, similar stock with a cam(uknonown told it was one up from stock) . My cam choice is going to be conservative on a 400 nothing over 5500rpm range and starting at 1000-1500. I got a lifter tick I've had since I got the motor so cam change is excusable. lol
    I got 17mpg running 80mph passing late models on I-35 2400rpm last night
     
  3. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Mike Jones doesnt work at Wal-Mart. Neither does Harold Brookshire...:rolleyes: yea, I know what you are thinking, Who?? How anyone can take any cam company with a "one size fits all" lsa seriously is beyond me. But then, they DO have the biggest advertising budget in the business...
    Dont worry, I'm done here, nothing to see, just another HAMB cam thread...Let the BS roll, I gotta go eat my prunes and take a dump...
     
    Last edited: Jun 10, 2013
  4. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    Certainly Top Cam designers, I hope Harold is doing well after his stroke.

    Not sure why it's required to be disagreeable to disagree,

    A look at some of the cams here, i think the Voodoo was harold's work?

    I am sure Jones's H71330 would do fine but he probably has a better cam by now if you call him and you want the personal touch (704) 489-2449, the website is kinda old.

    Harold is at 662-562-4933.

    [​IMG]

    Have a nice dump, preferably well done !!!
     
    Last edited: Jun 10, 2013
  5. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    I'mm off the plane and it's easier to type so I thought I would add some notes to the chart above.

    There are some rules of thumb in cam selection according to guys like Crane and Vizard as well as some of the above mentioned designers. Nothing is absolute and with the asymmetrical lobes we have today there are variances.

    but those caveats aside, on an engine like this with decent intake flow the power output will be relative to the area under the cam lift profile.

    The intake closing point will have a lot to do with where the torque curve is centered, the sooner the lower.

    Until be break something this engine would make more and more power with more and more cam.

    With it's Rod/Stroke ratio it will likely hurt the cylinder walls over 6,000 RPM.

    Practical peak HP would be 5500 to give us 500 RPM over run.

    The HI numbers relate to Hydraulic Intensity. Crane defined it as 004 duration - .050 duration. Advertised is now usually at .004 - .007 so we are ballparking a bit.

    Running thru various simulations 230 @ .050 seems to be close to the limit for our engine, while higher durations will permit more lift and show more power the OP want's to be in this 5500 - 500 lift window.

    So in effect if we got a Voodoo 272 (they don't make it) that would be the "hypothetical" intake lobe.

    The Voodoo 276/286 is a notch above, the 268/276 is a notch below but either would work well, the 276/286 might entice you to go visit Peter and TinkerBell.

    The Lunati/Brookshire has the lowest HI which means for a 268 advertised they beat the XE268 in their own dyno tests and in simulations, but they would likely be a notch below the XE274 H. Although we are searching for extremely small differences.

    The Gotcha, all the lobes below 50 HI require diligence in cam installation.

    Lifter crown and lobe taper need to be just right, you would benefit from Lifter Bore grooving or other oiling improvements, nitriding helps too as well as breakin rockers..

    Please read this if you select a below 50 HI cam or you will be one of the guys saying so and so cams are crap.

    The lower the number the more diligent. Now why recommend the thumpr in the first place if we know it isn't cutting edge HP wise like the Lunati and the Extreme Energy?

    This is a street rod and not a NHRA stock eliminator engine, the Thumpr 52/56 HI are much less agressive lobes but it has the sound if not the max HP of the edgier cams and it's 37 Intake closing helps down low.

    This is a Tunnel Ram 5500 rpm show engine which will go quite well IMHO.

    So without saying anyone is a JC Penny, or a Hart, Schafner, Marx, or a Saville Row bespoke kinda cam guy I hope this is educational, I always thank the guys who taught it to me.

    FG email this to Harold or Mike and tell me what they say :) I have listened to Harold speak before and I am more than sure he could teach me loads. Let's see if I listened well...

    Is UDHarold a member?
     
    Last edited: Jun 10, 2013
  6. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    No, but him and Mike can both be found on Speedtalk.
     
  7. coupemerc
    Joined: Jul 16, 2007
    Posts: 406

    coupemerc
    Member

    FWIW... I have run a Comp 292 in a 10.25/1, 406 with dual 500 cfm carbs. It was on the street in a 2600 lb stick car with 3.42 gears/31 tall tire. That cam had a radical idle, got 17 mpg and pulled okay.
     
  8. awsomeears
    Joined: Feb 5, 2011
    Posts: 159

    awsomeears
    Member

    I emailed Howard Cams a few days ago, gave them all my info from top to bottom and they recommend

    http://www.summitracing.com/parts/hrs-cl112431-08

    This thread is awesome and I'm learning a ton, thank you !!!

    Hoop I will also get another measurement in a day or two on my rocker not the valve retainer, I thank you for your info !
     
  9. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Well,I promised myself I was gonna do what I usually do, and just ignore the crap that always gets posted on HAMB cam threads, but I feel this post is deliberately misleading.
    So the THUMPR is ground 5 degrees advanced. Lets compare apples to apples, and advance the isky 5 degrees, and see what happens. I dont know what calculator you used, or where you found it on the internet, I am gonna take a couple minutes out of my day and use Performance Trends Engine Analyzer Pro, as thats the tool I usually use for this stuff.
    Wow, quite a difference. Using the 9.2 compression ratio that the OP offered up, I get a dynamic compression ratio for the isky of 6.87, and a projected cranking compression of 165. The Thumpr showed 7.04 and 171.
    The thumpr will make less power than the isky, as the intake duration is shorter, and it will get considerably worse part throttle fuel economy, due to the superflous 5/6 degrees of extra exhaust duration that they add, for NO OTHER PURPOSE than to make it sound more ummm "bad-ass".
    Now the 107/108 LSA in both of these cams is beneficial in a 383/400, but if you want to stick with comp, the only way to get that narrow LSA is to buy the "Thumpr" with the dumb-ass, no purpose, 5 deg. extra exhaust duration.
    If you want a "comp cams":rolleyes: cam, and you dont want the extra exhaust duration, you get to buy one of thier "one size fits all" 110 LSA cams. But dont worry, if you call them, they'll be happy to tell you that is what you need, and the 110 LSA is just right, no matter if you are are building a 327 or a 400, or hell, even a big-block Mopar for that matter. Whatever it is your building, the 110 LSA is perfect, because thats what they sell. I think if you call around, other cam companies might disagree, but hell, how often do you see a build in Hot Rod or Car Craft with a Lunati/Crane/Howards/Isky ect etc etc cam?
    You figure it out.

    PS: I notice Howards also recommended a cam with a 108 LSA. Wow! How about that??:rolleyes::D
     
    Last edited: Jun 10, 2013
  10. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    Their recommended cams (Comp) go from 107-114 LSA, not sure what u r saying? Can you post numbers instead of eye rolls? ps your guy Howard was 110-106??
     
  11. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Posting numbers is great, but it really doesnt help if the people throwing them around dont know what they mean.
    Comparing cranking compression numbers between two cams with one cam straight up, and the other advanced 5 degrees, makes it crystal clear that the person posting them either A) doesn't understand valve timing, or B) is deliberately trying to mislead. Either way, its not a conversation that I want any part of. The OP has sent me a pm, and I have responded, so you can go back to "holding court". I really have no vested interest in carrying this on any further. Have a nice day.:)

    Oh, and I didnt recommend the Howard, someone else did. I feel its too small.
     
  12. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    C: that's the way the cam is ground, good day!


    While the LSA is 107. the ICL is 102, vs LSA 108 ICL 108. for the Isky.

    [​IMG]
     
    Last edited: Jun 11, 2013

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