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Cams that work with TBI?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BLzr4x4ngkid, Jul 29, 2001.

  1. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    Looking to possibly drop a cam in my truck. I want something that lopes a little, but nothing that's going to just shake my truck apart. The only problem is the TBI. What would I have to do and what kind of cam would get me there?

    Pedal mashed and KICK'N ASS!
    WFO! Wide [censored]'n OPEN!
     
  2. '73 K5

    '73 K5 1/2 ton status

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    Thats right man. You heard my Blazer the other day and now you want a cam like me. LOL Damn, we sure heard some big cams last night.

    '73 K5
    Chevy good...Ford bad
     
  3. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    Yes, yes we did! Especially two of those Camaros. They vibrated my insides when they were just IDLING by. I need one of those cars!

    Pedal mashed and KICK'N ASS!
    WFO! Wide [censored]'n OPEN!
     
  4. Twiz

    Twiz 1/2 ton status

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    Injected engine generaly don't like valve overlap (thats what causes the "lopie" idle). Comparing injected cams shaft grinds to carbed grinds- the lobe separation is wider on the injected cam shafts, intake and exhaust lobes are spread apart so there is less valve over lap. Wider Lobe Separation- causes less "back" flow into the intake, better smoother idle, wider-flatter torque curves.

    Basicly, with an injected engine- getting a lopie idle is a up-hill battle that would degrade the performance and open up a hole bunch of other problems.

    Twiztid
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    A lopey idle in a truck kills your low end torque anyway and makes your truck a total dog.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  6. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    Ok, that answers my question. What kind of cam would work in my truck then?

    Pedal mashed and KICK'N ASS!
    WFO! Wide [censored]'n OPEN!
     
  7. solowookie

    solowookie 1/2 ton status

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    comp cams has an extreme 4x4 cam that a lot of guys is running here.

    pretty quick (in the next month) I'm putting Vortec heads with that cam, intake, and a 454 TBI with a custom chip. this is going in my on-road k5 with a gear swap from 3.08 to 4.10 so I can get the thing a good power increase.

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  8. Twiz

    Twiz 1/2 ton status

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    Most of the comp cams exteam 4x4 cams are ground on a 111 deg lobe separation, I think that is just a little too narrow for a F.I. engine. It might work out o.k. as long as the duration is kept to a minimum. (duration and lobe separation are diractly related to valve over lap) Most F.I. cams that I've seen are ground on a 113 up to 115 lobe separation angle. (I'm sure someone out there will disagree with that, but thats what I've seen/heard and read- If you think about it, it makes sence)
    Carbed engines like to see L.S.A. of 110 to 112 deg. Anything less than that is strickly raceing stuff (108s etc.)

    The very best advise is to call a cam manufacture (as someone else said in another post) Call several manufactures and see what they have to say. They grind them, and they know what they grind them for.
    But, if you guys are anything like me and I'm sure you are, because your HERE. I like to know the ins and outs and why.

    FYI
    Lobe Separation Angle (LSA) and Lobe Displacement Angles (LDA) are the samething.

    Twiztid
     
  9. solowookie

    solowookie 1/2 ton status

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    hey guys at turbo city (<a target="_blank" href=http://www.turbocity.com/TBIPowerMain.htm>http://www.turbocity.com/TBIPowerMain.htm</a>) gave me the following specs for running the vortec heads; under 208 deg. on intake duration at .05 112 deg. lobe centers or less.

    here is the following parts list that I'm using for the swap (if there is anything else that seems out of place)

    975-105 454 $529 TBI (turbo city)
    #12496821 intake $276.50 (gmpartsdirect.com)))
    CCA-12-231-2 crower cam $96.95 (summit) 111 lobe, duration is 206 on intake 214 exhaust
    CCA-812-16 lifters $30 (captcrunch)
    #14101083 vortec heads (captcrunch)
    custom chip from fastcity.com

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Your fuel injection will be fighting this Xtreme 4x4 I'd bet.

    I've got one in my motor, it's AWESOME! It turned a 145 HP 305 into a 250 HP one (I've got a few other goodies too). Mine's 204/214 @ .050" .432"/.453" 111 LSA, the smallest Xtreme 4x4. Keep in mind the ramps are very agressive too, it's 250/258 advertised duration.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  11. ken

    ken 1/2 ton status

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    Crane makes a line of "Compu Cams" as they're called, that are designed to work with TBI and be smog legal in Calif. I plan to put one in my crewcab dually's 454. The duration figures of the mild version are in the 210 degree range at .050" lift. I'm hoping it will really wake up my dually.

    ken
     
  12. CaptCrunch

    CaptCrunch 1/2 ton status

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    Comp Cams, Crower, Crane and quite a few others make cams that are tested and designe to run on FI applications. The 111 degree overlap works well w/ the lower durations as Twiz said. You can also start playing w/ modified sensors... most specfically the MAP to allow a longer duration. Quite a few guys in the TPI Vette crew are running these w/ some pretty lopey cams for FI. I'd say keep it simple and just get a computer grind from the manufacture of your coice.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</a>
     
  13. solowookie

    solowookie 1/2 ton status

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    OK guys, I've made a few calls this morning, and here is what I have found;

    my first call was to fastchip.com (who's going to be burning my custom chip). they recommended going with crane cams because they are most familiar with them. they told me that I could go with any cam manufacture as long as I had the specs, but said they had best results with crane. I figure I better stay with their recommendations.

    next I called summit, and a few cam manufactures. I've settled on the following cam; duration at .05 intake is 204 and exhaust is 214. lobe separation is 110! (yea you read that right). part # is 114122 (summit's is crn-114122).

    when I called crane I was concerned because the cam said it gave good mid range to top end hp (and yet the operating range was 1000 RPM to 4000 RPM). the cam below it gave the characteristics I wanted, but had a note that in 350 applications the next one needed to be used. crane said I needed to use this cam, but to advance it 5 degree's and it would give me the low end grunt.

    <blockquote><font class="small">In reply to:</font><hr>

    Crane CompuCam camshafts have special profiles designed to improve engine performance without sending the computer into fits or causing the stalling, surging and driveability problems some "computer-compatible" cams are known for. Cams are 50-state-legal and come with lifters.

    <hr></blockquote>

    I also was trying to find a cheaper source for a TBI (454 that turbo city recommends). the dealers price on a 454 TBI is $1021, and gmparts direct is over $600.00 so I think I'll stick with $529 from turbo city that comes with matched injectors.

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  14. Twiz

    Twiz 1/2 ton status

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    This kinda of stuff can sure ruff up the frontal lobes!

    The point I was trying to make, excesive valve overlap is a bad thing with F.I. Over-lap is dependent on L.S.A. and Duration.. If the duration isn't exsesive then the narrower LSA can be used. If the Dur. is higher, then the LSA needs to be widend. But, as a general rule, Fuel Injected engines don't need close LSA, so why not use a wider LSA and get a better (for 4X4s) flatter torque curve, it would have less peak torque, but more of it on the average. Speed Density (T.B.I.) sys with Map sensors arn't very "adj." and need to have special atation paid to "back flow" and pulses backward into the intake manifold. MAF (Mass Air Flow) style sys like some of the TPIs. are a bitt more forgivable.

    Sorry for confuseig anyone, I was tryng to get the idea across that a cam for a carbed engine -might- not work the same for a F.I. engines.

    Again, The best bet is to call a cam tech line. They know what is what. They know way more than I could ever know, but I don't like to go into anything blind.

    Ohh, Solo, If you are planing on gong with a BB, check on a "cam oiler". I'm not totaly up to snuff on the Big Block program, but I've heard that they like to eat up cam shafts due to poor oiling of the cam lobes.

    Twiztid
     
  15. jarheadk5

    jarheadk5 1/2 ton status

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    I read that too. Shawn has a feature on that cam oiler on his engine buildup pages on <a target="_blank" href=http://www.off-road.com/chevy/>www.off-road.com/chevy/</a>. If I ever get a BBC-anything, I'll be installing a cam oiler.

    If at first you don't succeed, failure may be your style...
    [​IMG] <font color=green>Semper Maintenance!<font color=black>
     
  16. CaptCrunch

    CaptCrunch 1/2 ton status

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    Like Twiz said it would flatten out your torque curve more, but I think the computer cams out there are kinda of a compromise.

    Yeah the MAP sensors are a PIA, but there are quite a few places offering modified ones. One of the shops here modifies them, but I have yet to see any results on the TBI/MAP combo from them. The vettes and camaros w/ the MAF type system are easier to modify, but there is also a lot of speed density style TPI's. Just an example.... in the 5.0 Mustang crew, a very popular swap is to swap the speed density cars over to the MAF system. It isn't too tough and actually can be done w/ junkyard parts... the main down side is taken a look at bigger bore MAF's? OUCH! Plus there are still a lot of guys fighting problems in this aspect.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</a>
     
  17. solowookie

    solowookie 1/2 ton status

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    man guys I hope you don't think I'm not listening to your advise cuz you KNOW that I am. I've had enough personal exerience with Eric and Mikey (as well as some others) that I'm very aware that you don't take your advise lightly.

    I've made a LOT of calls and talked with a lot of people about cam specs. Everybody is saying EXACTLY the same thing you are. <font color=blue>You actually saved me from ordering the cam I was going to from comp cams.</font color=blue> the cam that had the 111 lobe wasn't computer compatible.

    I don't really understand all the details (at least I don't remember the details long enough to explain them properly) to tell you why this last cam I'm going with works.

    this crane cam #114122 is designed specific for computer applications. (it is a crane cam compucam series now renames powermax cam) somehow they take the tight lobe # and compensate for it with the lift duration to make it work really well for computer applications. I made them explain it to me until it all made sense, but I've seemed to forgotten the details (if you asked my wife she'd say that was pretty typical LOL)

    I talked with fastchips.com about the custom chip I wanted burned, and they recommended this cam. I was concerned about some of the specs so I call crane up, and they also recommended this cam for my application??? it is a hydralic cam so I'm going to go ahead and use the lifters I'm getting from Mikey with it.

    the lifters are comp cams, and the cam is from crane cams. I'd like to go with crane lifters, but I'm getting such a good deal on the lifters from capt. that I can't resist.

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     

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