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383 tbi cam choice?

Discussion in 'The Garage' started by camok5, Jan 2, 2007.

  1. camok5

    camok5 1/2 ton status Premium Member

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    I posted in the injection section but figured I might get more help here.http://coloradok5.com/forums/showthread.php?t=194522. I have seached here and on Thirdgen but nobody seem to agree. I would like to keep the cam thats in the engine or at least find another tbi friendly cam that will work. Smog is not an issue and I will be upgrading my chip, tbi, etc, I just want to know how big a cam I can use that will make good low end torque? Also the block I'm using is a 4 bolt pre 87 and I want to know if I can put a roller cam in it, I just want to keep my options open?
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Cam is going to be spotty. I see the lobe separation is 111*. I guarantee a few people out there have made 111* cams work with injection. I'm running a 112* and it's extremely mild. Another degree can be made to work. But it will take effort.

    Roller cam in a non-roller block is a WASTE of money IMO. I went that route, and it cost me over $500, for a cam and lifters that are, IMNSHO, inferior to stock pieces. It's MUCH smarter to start out with a stock roller block in the first place.

    Big cam and low end are pretty much mutually exclusive. A small cam typically shows very strong low end, with penalties higher up in the RPM band. Just look at the HP/TQ numbers of any of the smog era Chev V8 engines, you'll see that HP suffers quite a bit, but torque is still very strong, and very low.

    If you don't have it, desktop dyno (2000 or later) is a very useful tool in illustrating exactly this.

    http://dyeager535.topcities.com/miscpics.html Hope you aren't dialup, but the first two pics are TPI with the cam I've got. The first graph is a 283 (just showing no replacement for displacement) the second is essentially what I've got now, with long tubes. You'll quickly notice torque is going DOWN at 2000RPM, which is pretty darn early. \

    On the street, that motor runs out of steam pretty quick, but plenty of low end power for sure.
     
  3. camok5

    camok5 1/2 ton status Premium Member

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    Yeah I didnt think switching to a roller cam would be worth it especially in a 4x4. What do you mean by it will take effort to make it work? I already plan on upgrading my tbi, fuel pressure, and chip but what else would it take to make it work?
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Making a "radical" cam work, and work well, is a tedious process of tuning a chip. (for those of us doing it ourselves with old school PROM stuff)

    To me, there is NO other way to make it work right other than to burn chips yourself, or have a dyno tuning session where they tune it real time. This is simply not an application where you can give someone specs and they can get it right via mail on the first shot. This is the reason you see such widely varying information on the cam choice...not only are there a whole bunch of variables such as application, engine size, cam specs, and injection setup, but also the ability and dedication to making it work right on the part of the person with the vehicle.
     
  5. MaxPF

    MaxPF 1/2 ton status

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    It depends on the lifters. I agree that the common vertical bar lifters aren't the best setup - I don't even like 'em in race motors that are routinely torn down. The horizontal bar lifters OTOH are fine. I agree that using a newer style block already machined for GM roller lifters is preferable, but if someone has a good pre-roller block there is no reason not to use a good set of aftermarket roller lifters and a roller cam. Here's a pic showing the difference between the vertical bar lifter and the horizontal bar lifter:

    [​IMG]
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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  7. MaxPF

    MaxPF 1/2 ton status

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    I didn't notice that :doah: I don't know if anyone makes a horizontal bar hydraulic roller lifter... I'll have to research that...:thinking: I've only used the solid rollers, and it was years ago. IIRC Crane used to make a horizontal bar lifter, and that is what we used. I remember we never had a problem with em though...
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    As a for instance, COMP cams sells a retro roller cam/lifter (hydraulic roller of course) for $680 at Summit.

    Comps instructions say right on them not to idle the engine for very long with the retrofit rollers. What's with that? (I know it's a design issue, just pointing out that the factory NEVER said that was a problem)

    For that much money, hassle, and inferior design(IMO) either get a roller block, or spend that insane amount of money on something that will make a BIG difference, like heads.

    I understand the poster is already "stuck" with a non-roller engine, but I'm just reiterating all the reasons the retrofit cams suck for what you get and pay.
     
  9. camok5

    camok5 1/2 ton status Premium Member

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    I still dont think I will go with a roller cam, it just doesnt have enough benifits for me vs. cost. Anyone else have a good hydraulic cam choice for me?
     
  10. MaxPF

    MaxPF 1/2 ton status

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    It looked to me like that was specifically for the solid roller lifters, not the hydraulics. Price is one of my big peeves with the retrofit lifters. 16 stock-type hyd. rollers will run about $200, while the same 16 retrofit lifters with a link bar will be close to $500. Still, a decent roller grind can build quite a bit more power and torque vs an equivalently spec'd hyd. flat tappet cam. Whether it is worth it depends on your wallet :deal:

    BTW, thinking about it I may have been mistaken about hyd. rollers ever being available in a horizontal bar version. IIRC the reason for using horizontal bar lifters (solids) was because they were designed with a seat in the top to accomodate rev kit springs... I wish I had some of my old cam catalogs lying around... :dunno:
     

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