71 340 4 barrel cuda cam decision

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    Author Topic: 71 340 4 barrel cuda cam decision  (Read 2564 times)

    Offline culp71

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    71 340 4 barrel cuda cam decision
    « on: January 19, 2015 - 08:28:49 AM »
    all,
    looking for some good info as I have done many restorations, but mostly 40-55 cars and trucks, very different engine setups, so I have not played around with various cams.
     I do not have a complete grasp on cams, I have researched and gathered some info about lift, duration, center line etc. but nothing that clearly explains what characteristics these different factors change.
    So I am just going to rely on this vast wealth of mopar cam knowledge here.

    I have it narrowed down to one of these cams:

    I want a reliable but slightly loob at idle (if possible), good low end torque, and I don't much care about anything above 5,000 rpm
    I also don't want to do any crazy head work (original J heads), as close as possible to original,(but a slightly loobie idle)
    which one of these would get me closet to that?

    A. 204/214    421/444
    B. 204/204    420/420
    C. 268/276    429/444 (mopar original)

    or I will go with mopar original (c) but with a shaker hood I thought a slight "shake" at idle would be proper, as it looks and would sounds killer.

    thanks.
    « Last Edit: January 19, 2015 - 09:07:55 AM by culp71 »
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    Offline moper

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #1 on: January 19, 2015 - 12:02:09 PM »
    If the goal is a little note in the idle - I think I'd go a little bigger than stock - but - given the three choices - I'd use the Comp Cams version of the factory cam. It's ground on a 110° ICL rather than the factory one which was I think  114°. Another choice would be a true version of the '68 manual trans only 340 cam. Not sure who offers that tho.
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    Offline Chryco Psycho

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #2 on: January 19, 2015 - 07:34:30 PM »
    Lunati VooDoo 702 or 703 cam
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    Offline culp71

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #3 on: January 21, 2015 - 10:08:46 AM »
    so a 110 degree lobe separation would give me the idle with a slightly lobe ,compared to the 114 degree cam which would be smoother at idle?
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    Offline culp71

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #4 on: January 21, 2015 - 01:30:27 PM »
    just looking for some basic cam info....

    to achieve a lobe-y idle which factor or factors need to be changed on the stock cam to achieve this.
    longer lift?
    longer or shorter duration?
    intake or exhaust?
    lobe separation increase or decrease?

    Thanks



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    Offline moper

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #5 on: January 21, 2015 - 05:50:52 PM »
    The cam's only a part in a system. So other factors also contribute to idle quality. The problem is, most things that afect idle, have a negative affect. The Shaker's going to move when you drive the car anyway. A raspy idle will make it shake at idle, but it also means (usually) a lower vacuum signal, potentially fouling plugs faster, etc.
    Tightening the LSA will do it, adding lift will do it, adding duration will do it.
    Ironically the changes that also make idle get worse, are usually beneficial to greater power output. So it's easy and you don't need to think much. Buy a performance cam (a smaller one) and it will shake more at idle...lol. An old favorite of mine is the Comp High Energy 268H. It has a nice rumble to it. You would need to replace the stock valve springs with it tho.
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    Offline Moparal

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #6 on: January 21, 2015 - 06:02:37 PM »
     :bigsmile:  you'd really love my cam

    288/296 @50
    113 lobe sep and 113 cl
    788/799 lift

    It idles at 1600 but revs and pulls to 8400  flowing through head chambers like oldschools A body, but it is just a wedge  cam works very wellbetween 6k and 8400   Of course I have a 6200 stall
    Oh you ment 340  never mind.  Make sure you are matched in all phases of your build and drive train especially with a shaker and intake limits
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    Offline dfrazz

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #7 on: January 21, 2015 - 06:44:58 PM »
    Quote from: Moparal on January 21, 2015 - 06:02:37 PM
    :bigsmile:  you'd really love my cam

    288/296 @50
    113 lobe sep and 113 cl
    788/799 lift

    It idles at 1600 but revs and pulls to 8400  flowing through head chambers like oldschools A body, but it is just a wedge  cam works very wellbetween 6k and 8400   Of course I have a 6200 stall
    Oh you ment 340  never mind.  Make sure you are matched in all phases of your build and drive train especially with a shaker and intake limits

    Al, post a video of that idle if you can.
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    Offline Moparal

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #8 on: January 21, 2015 - 10:50:06 PM »
    I will in a week or so, it's in the chassis shop getting 2 3/8 tube headers made for it.  Nothing ever sounds good on a vid. It may just sound likie popcorn popping is all. 
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    Offline dpcd67

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    Re: 71 340 4 barrel cuda cam decision
    « Reply #9 on: January 23, 2015 - 11:09:07 PM »
    I used the Comp 268; it doesn't have any lope though but I didn't want any. Much more power than stock but I upped the compression to 9.5 as well (on a 73 340)
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    1963 Dodge M37 (3)
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