484 purple cam..JUNK

Mopar Performance Issues

  1. jameskernz

    jameskernz duster Man

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    I have a 340 with a 4 spd.,single plane intake, headman headers, stock heads, holley 650 DP., 3.73 gears. It has the 484 /108 cam in it and I have tuned it many times. Getting it to idle and perform, drivability is terrible. I have decided today after another tuning session to get a new cam! :protest:Does anyone have any suggestion? I would like good drivability, with a good sound..95% street driving
    Thanks,
    Jim
     
  2. 70aarcuda

    70aarcuda Master Hoader of SBM FABO Gold Member Legendary Member

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    how much initial timing do you have ?
     
  3. RustyRatRod

    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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    If you have adjustable rockers, the MP 528 would be a kick in the pants compared to the 484.
     
  4. jameskernz

    jameskernz duster Man

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    20 btc
     
  5. jameskernz

    jameskernz duster Man

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    no standard rocker assy.... Was thinking about the Hughs Whiplash
     
  6. crackedback

    crackedback FABO Gold Member FABO Gold Member

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    Did you degree it when installed? In a 340, they like to be installed at 102ish.

    I'd crank as much initial timing into it as the starter will handle and see where you end up. It may want 28*. I have a tight lashed 284/528 mechanical in a stock compression 70 340, liked 24* initial and will idle real easy at 800 rpm.
     
  7. jameskernz

    jameskernz duster Man

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    installed the cam at 104. I will try more advance,, it also seems to want the carb real rich.
     
  8. krazykuda

    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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    Don't give up on that cam yet!

    Install a set of Rhoades lifters P/N 2018. I have the same cam in my 68 Barracuda 340 - S and it runs great with the Rhaodes lifters. They take out 15° duration and .025" lift at idle and slowly ramp up to full lift and duration of the cam by 3500 RPM. I have a stock 340 with the .484 - 284 MP cam, auto with stock converter, 3.91 and Holley 6711 650 DP with a stock thermoquad spread bore cast iron intake and it runs great with Rhoades liftes. Without them I could hardly idle at 1100 RPM, with them, I"m idling at 850 RPM. I can smoke the tires all the way to 6500 red line. It is installed straight up like stock cam, no degreeing. I'm running electronic distributor without vacuum advance hooked up, recurved, 17° idle and 36° total.


    http://www.rhoadslifters.com/Pages/PartNumber.html


    Read the test at the bottom of this page:

    http://rhodeslifters.com/Pages/Articles.html


    Order a set from Summit Racing and give them a try. They'll help.


    If you give up on the cam and want to throw it in the trash, I'll take it off your hands.....
     
  9. 68383GTS

    68383GTS Well-Known Member

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    I would stay away from Hughes garbage...
     
  10. crackedback

    crackedback FABO Gold Member FABO Gold Member

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    Try More timing first.

    Remove carb and look at the transfer slots on primary side. If they are more than a square shape opening, try opening the secondaries a little via adjustment screw so you can close up primaries to maintain idle speed.

    IMO, it should idle pretty easily in the 800-900 range and not burn your eyes out from a rich idle setting. Being a 4 speed it can idle a bit higher, but, shouldn't be necessary.
     
  11. mopardude318

    mopardude318 Well-Known Member

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    pretty broad statement...
     
  12. jameskernz

    jameskernz duster Man

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    I did open the secondaries some. I have been doing this also, put the secondaries adjustment srew in from the top down for easy adjustment. Even brought the float levels up for crisp idle but that didn;t work well at stops. I will try some more tomorrow, after I get the floats correct. we put a snapon scope on it today to get it as good as it is, got it to idle at about 900, but driving it with the floats set high was a challenge, with idle all over the place. Thought about drilling the throttle plates but did not. It also sucks gas like crazy
    Thanks
     
  13. RustyRatRod

    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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    I agree with trying to tune what you have. That's not the original question you asked though, so I gave my recommendation.
     
  14. 805moparkid

    805moparkid Slant and AFX Guy

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    no offense do you know how to tune a carb? sent the floats to where the it barely dribbles out RUNNING out and leave it alone. start at 2.5 turns out on the idle mix screws. as they said make sure you have plenty of timing into it, at least 18* at idle, say 34 total @ 2500 rpm.

    now you can start tuning it...
     
  15. 805moparkid

    805moparkid Slant and AFX Guy

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    also what do you have in it for a PV? whats your idle vacuum in gear?
     
  16. crackedback

    crackedback FABO Gold Member FABO Gold Member

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    Set floats so it barely wets the threads of your sight plug hole at idle.

    Higher float levels make the rich idle worse!
     
  17. jameskernz

    jameskernz duster Man

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    Idle vac. is 10(4spd), PV is 6.5
     
  18. 805moparkid

    805moparkid Slant and AFX Guy

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    :blob:
     
  19. jameskernz

    jameskernz duster Man

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    I appreciate the suggestions
     
  20. 805moparkid

    805moparkid Slant and AFX Guy

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    i would go down to a 4.5 pv
     
  21. krazykuda

    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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    Try Rhoades variable duration lifters!!!!
     
  22. 1969383S

    1969383S FABO Gold Member FABO Gold Member

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    "484 purple cam is junk"

    That cam has been around a long time and a good piece.

    I have always installed them @ 108 on the 340.

    Sounds like something else is being overlooked!

    Like said before check your initial and total timing. If this is an early hi-po 340 that 650 DP should make it idle and perform pretty good right out of the box. I would be using a 750 DP though.

    Some times you do to many things trying to get it right that your tune goes way to the bad and you need to go back to square 1.
     
  23. Johnny Dart

    Johnny Dart Well-Known Member

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    I think the single plane intake is killing you.
    I would start by going to a good dual plane intake. (Ede RPM or Air-Gap).
     
  24. rumblefish360

    rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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    Man! I had a bud make 430 HP in that one with a lot left on the table.
     
  25. OldmanRick

    OldmanRick Well-Known Member

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    Even in a low comp 340, that cam should be tunable with your combo, for reasonable street manners. Send it to me and i'll get it right......and have it back to you in a year or so :mrgreen::mrgreen::mrgreen:.
     
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