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Cam Choice, 401, 727, 3.55 Gears?

Discussion in 'Intermediate CJ-5/6/7/8' started by 70cj5134f, Mar 13, 2020.

  1. Mar 13, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    Crashed my 401 gremlin,(500HPish) built 20 years ago. Engine going in my J10 pickup. Teck has changed a lot since build. I'm replacing my offey 360 with an air gap, Now let's talk cams?
    My machine shop( built dirt tra k cars for locals) ordered me a custom reed cam.
    Card long gone. I remember tight lash around .012. 250 @50 dur and .590ish lift.
    Pulled Strong from 2500rpm all way to 6500 rpm. With a T10 3.73s, it was Bad rump?
    Now in a 5200lb truck do I need to change cam?
    I really like the lunati voo doo series , have 1 in a 455 Pontiac, and it's a tq monster!
    Don't really want too give up any hp? Unless it's. A tradeoff for more tq?
    Planning a rering and bearing rebuild, engine around 25K, hard miles.
    Recommendations.
    Comments?
    Thanks!
    61 year old gear head!
     
  2. Mar 13, 2020
    Rich M.

    Rich M. Shoe salesman 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Personally I'd dial the duration back to bring the torque lower in the rpm band. I like Lunati as well. Their tech dept is good, give them a ring.
     
  3. Mar 14, 2020
    duffer

    duffer Rodent Power

    Bozeman, MT
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  4. Mar 15, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    Going with either my current cam, or a voodoo.
    Rollers tooo much $.
    Really like the look of the voodoo704?
    Anyone run a 704?
     
  5. Mar 15, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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  6. Mar 20, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    I joined their forum several days back, still can't post?
     
  7. Mar 20, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Which one?
     
  8. Mar 23, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    International .
    They got it on now .
    No one their has used a cam that large, I may have to be the ginny pig?
     
  9. Mar 23, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    For what its worth, I have built many, many engines. I used to put "big" cams in most of them, and some were fun in the muscle cars. As time has gone on, I have gotten much more conservative in my cam selection. Many of the "RV" and towing cams have proven to be very satisfying. They typically wake up an engine, but still have a smooth idle.
    I have installed several Voodoo cams and like the asymetric intake/exhaust aspect of them, and they do make an agressive sound. I have found you have to use some heavier valve springs because these cams have a very aggressive ramp angle. I generally like a lobe separation of around 112 degrees for a broad torque curve. A 401 has great torque to begin with, and these don't like to rev like other smaller bore engines. You mention that you have an automatic and 3.55 gears, but need to include tire diameter in your J10. These are all factors to consider when selecting a cam. A J10 is a very different vehicle from a Gremlin, so you could get away with a high lift (.590), but that likely won't be a good fit in your J10. I'd keep lift around .500 or under, and look hard at a cam thats more on the conservative side.
    -Donny
     
    Last edited: Mar 23, 2020
    Rich M. likes this.
  10. Mar 25, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    Tires are 32s.

    Which voodoo would u use?
     
  11. Mar 25, 2020
    Keys5a

    Keys5a Sponsor

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    I read up on Lunati's cam specs for the Voodoo AMC line.
    For a J10/401/auromatic, I would likely use the 702 for my own use. The beauty of a 401 is the massive torque, though it still pales to the torque of your 455. I haven't built a 401 since about 18 years back and they're getting hard to find. This would still be a big upgrade from the stock 401 emissions cam.

    The 703 is a bit hotter, and would possibly be more fun for a "play" vehicle, but if driven daily, I wouldn't want it personally. This would be the biggest cam I could see used in a J10, but the truck wouldn't pull as well down low, which to me, is the purpose of a truck

    The 704 would be fun for your Gremlin, but I don't think so much for your truck. The power is just too high up in the rpm band, needs high compression to get the benefits of the cam, and also requires a high stall converter for the transmission. If you were building this to drive like a race car (truck), go for it. This is just too much cam, making your truck unusable for the majority of daily use. If you only use it to take to the track, it could be fun, but you'll get beat by about everything else at the track.
    These are just my opinions! Please take no offense.
    -Donny
     
  12. Mar 26, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    I don't want to make the truck, unusable for farm work!
    I do want it to be mostly a toy, not a trail rig.
    I miss the thumping big cam, through 3in exhaust?
    Going to rebuild as is, test drive, then change cam accordingly.
    Thanks
     
  13. Mar 27, 2020
    Rich M.

    Rich M. Shoe salesman 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Just thinking out loud. Some don't like them, some do ymmv. Rhoads lifters are popular with Buick guys to tame bigger cams on those lower revving engines. Might be a relatively cost effective experiment on your existing cam. I've run them, seem to work as advertised but a little "ticky" at idle.
    Rhoads Lifters
     
  14. Mar 29, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    Can u run Rhodes hyd lifters on a solid cam?
    Might be a option?
    And I'm already used to the ticking!
     
  15. Mar 29, 2020
    Rich M.

    Rich M. Shoe salesman 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    They have a version that can. Call the tech #
     
  16. Mar 29, 2020
    Keys5a

    Keys5a Sponsor

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    I run Rhodes lifters in my Triumph TR8 (essentially an alloy Buick 215). I have a Crane Cam in it, and needed to tame it a little for more low-end power. The lifters made a noticable difference. I wasn't aware there was a solid lifter version.
    Rhodes lifters operate hydraulically, allowing the lifter to bleed down at low rpm, essentially making a lower lift cam, taming the cam a bit. As soon as rpm builds more oil pressure and volume, the lifters pump up fully, giving full valve lift.
    They are fairly effective at giving me a bit of both worlds, but they can still float out on sustained top end (6,800-up) as I have found. This is in a very light car, so is very different from a J10.
    -Donny
     
  17. Mar 29, 2020
    Rich M.

    Rich M. Shoe salesman 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Same here. I ran Rhoads on a big dual pattern Crane in my OF231. Made almost 20" vac at idle. Idled nearly smooth at 800, revd up to near 6k pulling hard all the way. Scattered T90's and u joints on a regular basis....
     
  18. Mar 30, 2020
    70cj5134f

    70cj5134f Member

    East Tn
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    They make a V-max lifter that's adjustable with lash and has a super lube feature to keep lobe happy. I think I'll try them?
    Thanks all.
     
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