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Is my 454 weak?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Aug 20, 2001.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I have a freshly rebuilt 454 with stock heads and an Edelbrock Air-Gap intake. The cam is from Comp Cams, and is the "lowpy-est" (rough idle) cam they make, but it is still considered a "truck cam". I could get specs off the cam card and post the numbers later today...

    ANYHOW - I am kinda dissappointed at the lack of HP in my engine. I can't spin the tires on dry pavement (in 2 wheel drive). I thought that big blocks had alot of torque?!! I built this engine with the purpose of making ALOT of torque. If I can't spin my 35x12.5x16.5 tires, what fun is it to have a big block drinking my wallet dry every other day in gas money?

    Is my pityful engine really supposed to be this weak?

    You other guys/gals with big blocks, can you spin your tires?

    And dont get me wrong here folks, the truck is no hot rod, nor did I build it to be one. I am just concerned that since I can't do something as simple as spinning the tires, that maybe my BBC has some issues I could look for?

    Please help...

    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Post the cam numbers for us. I would suspect you are over-cammed for a low RPM torque monster. I can spin my 36" TSL's with my mild 350, and my rear end is welded. Mind you i have a 4 speed so i can cheat it a bit. [​IMG]

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  3. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Gear ratio's and tire height may have some effect. What gears do you have, and what is your actual (measured) tire height?

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  4. not4show

    not4show 1/2 ton status

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    Yea, gears and lockers will also have an affect as well. I can spin my 35s and I have a pretty much stock 350. I also have a detroit locker and 4.56 gears out back as well.

    Never put a stupid move passed a stupid person.
     
  5. '73 K5

    '73 K5 1/2 ton status

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    Yea, I agree with Rene about the cam. If its too lopey and more of a horsepower builder at high RPM instead of horsepower AND torque cam then that might be the problem. Since its an Auto tranny, I bet the stall speed is pretty low...which is good for 'wheeling...but if its low and your engine powerband is high, then you will have mucho trouble spinning those tires right off-idle.

    '73 K5
    Chevy good...Ford bad
     
  6. nyyef

    nyyef 1/2 ton status

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    you have overcammed your motor. all you mentioned was the cam and intake as your mods. you said you had stock heads.
    the torque has to be in the right place. remember that the "lopy-est" truck cam is actually a hot rod grind with the duration adjusted to bring the torque band--READ: a little-- lower. these cams are good for mudding and duning, where you usually have good run ups before the s**t hits the fan.
    torque carries you to the speed you want (wheel spin), horsepower keeps you there.
    give comp cams a call tell them what you got (tire size, ratios, tranny...etc), tell them what you want....and they will lead you in the right direction.

    Knife.
    knife.coloradok5.com
     
  7. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    FYI - my rear axle is a 14BFF, with a Detroit locker and 3.73 gears.

    1500 RPM stall
    34" actual tire height
    The cam was supposed to make more torque than HP according to Comp Cams...

    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    &lt;a target="_blank" href=http://24.10.209.54/bigolk5.htm&gt;http://24.10.209.54/bigolk5.htm&lt;/a&gt; &lt;img src="http://coloradok5.com/forums/images/icons/cool.gif"&gt;
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    So do you have 3.73's or 4.10's?

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

    454/TH400/NP205 - 14BFF/D60/w/ 4.10s

    <hr></blockquote>

    My Jimmy runs 3.73's too...if i didn't get really bad wheelhop i'd light em up and send a pic.[​IMG] True tire diameter is currently 35 1/4".

    If you could post the cam specs I'm sure that would help some of the guys here decipher whether or not you have too much 'cam' for the application. Other specs would help as well, Carb size, type of heads, compression ratio, exhaust mods...all these things can have an effect on torque.

    Rene

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  9. AGM73k5

    AGM73k5 1/2 ton status

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    I had 3.73 454 and th350 with 35's and couldnt spin them unless I had some gravel under me. I went to 4.10 and 33's and could light them up.
    Good luck,
    -Aaron

    ___ __ _ _ ____ __
    AGM73k5 -- ajgm1@yahoo.com
     
  10. CaptCrunch

    CaptCrunch 1/2 ton status

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    One look at the gears and cam like people have said. a loey cam ain't gonna give you huge amounts of torque obviously. I also don't reall like the air-gap manifolds for your application either. What heads are on on it? Oval or rectangle port? Have then been worked? Also what compression ratio? All these things will make a difference. What size carb are you running&gt; It all factors into the performance

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  11. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    The rear diff has 3.73 gears now, the D60 has 4.10s. I am only running with the rear driveshaft installed. Eventually, I will change the rear diff gears out to 4.10s. The truck has only been on the road for 3 weeks - I have not gotten to the gear swap yet.

    The heads are stock oval port heads. No porting, no nothing.

    The intake is supposed to make power from 1500-6500RPM according to Edelbrock.

    It does idle rough, but the cam is SUPPOSED to have been for a truck application according to Summit, where I ordered the cam from.

    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    A rough idle indicates a long duration cam. This is not gonna help you from idle to 4000 where you will be using the motor 99% of the time. Mind you when it is spinning a 5500+ RPM I'll bet it hauls pretty good!

    My 350 idles smooth at 650 RPM and pulls real hard off idle to about 4400 RPM where it runs out of steam. I never run my 350 over 4000 RPM anyways so its perfect for me. The cam recommended to me by Comp Cams was the 260 HE, 212 degrees duration at .050 and 447 lift as near as I can remember without the cam card in front of me.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  13. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    OK - the cam is a CRANE cam... here are the specs...

    http://cranecams.com/master/apps/chevy44.htm#4. PowerMax

    Choose the 3rd option in the first window.

    Here's the important stuff:

    duration @50: 216
    Advertised duration: 290
    Lobe seperation: 110
    LIft:.515int/.515exh.

    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     
  14. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    I'd say too much cam. I went with a 270 degree comp marine cam for my 468, knowing that I'd loose a little low end, but be able to wrap to 6K. The cubes and my Doubler take care of the low end pretty well I think. It will light them up pretty well if I use the front brakes, but not on take off. Even at sea level in 2:1 low range, it only left about 4-5 feet of black marks as I left on an acceleration run.

    For most off-road use, I'd recommend the 260 degree like someone else here mentioned. Even for running sand and mud, I would not go more than the 270 I'm using. Single purpose trucks can go a little lumpier.
    A good cam guy can also recommend some variations to help you with specific purposes. The comp rep I talked to hooked us up with a marine cam to get a wider lobe separation so the EFI would be happier with the idle quality, while still having a slightly lumpy profile.

    Making the world better, one truck at a time.
    SW-ORD
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  15. CaptCrunch

    CaptCrunch 1/2 ton status

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    Wholley Shnikes!!!! I agree... WAY too much cam... whatever rep recomended that has to be on crack. I personally like the 268 cams or a 264 if you can get one for BBC's. A 260 will really make it pull from the line...

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  16. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    The carb is a Holley 750CFM 4150 series. As for the cam specs, this cam is not that bad folks, is it? Its a pretty weak cam compared to the section below that, and the description even states that it should produce good low and mid-range torque...

    If my 750 carb it jetted poorly, would that do it too? It does kinda feel like it bogs when you jump on it... Anyone have jetting suggestions for a BBC with a 750CFM 4150 Holley?

    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     
  17. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'm no cam guru, but I feel that your cam is too aggressive for off idle stump pullin torque. Its a nice cam in a lighter vehicle with a high stall convertor. I've been real happy with the off idle snap the 260 HE in my 350 has given me.

    As for the Holley, others may disagree but I think the best thing to improve performance with it would be to use it as a wheel chock...[​IMG]

    I've personally had the Q-jet, a 600 Vac secondary Holley and lastly an Edelbrock (Carter clone) on my 350. My Q-jet had some serious issues due to age and had to go...the Holley was the absolute worst mod I could ever have made. Over 3000 RPM it made the most power of the 3 but under 3000 it was a tuning nightmare and I could not get nice crisp off-idle response. The Edelbrock I have now although not particularly stellar at bad angles has the best on road response of the 3. Very crisp and snappy off-idle response and makes very good power through 4500 RPM, and fuel economy is about even with what I got with my Q-jet (but it was worn out)

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  18. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Keep in mind that the numbers will look huge compared to a SBC cam specs. The 260H cam is great for a SBC, I agree, but they do not offer that same grind for a BBC.

    ATTN CARB GURUS:
    -------------------------
    But maybe Rene has something here... could it just be that damn Holley giving me problems? It was recently rebuilt and re-jetted. It has 76 primary jets, and 80 secondary jets.



    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     
  19. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Well I do understand that a BB will tolerate more cam due to displacement...but I would think that duration would have almost exactly the same effect regardless. Bigger lift would be almost necessary because of the cubes involved. Again, I'm no cam guru but if Stephen Watson is running a smaller cam than you are and feels his is on the edge of being over-cammed i think its still something that should be considered.

    Have you thought of running a few smaller cams through a desktop dyno for comparisons? I'm sure someone here has desktop Dyno and would prolly run some numbers for you...

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  20. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Rene-

    Great idea! Would anyone here be so kind to run my existing cam, and then one or two others for me in their software dyno? The cams that would be cool to see would be #1, #2, and #3, (#3 is what I have installed). Follow the link below for CraneCams webpage. The cam selection will be listed there, and the cams I am looking to have dyno'd are right at the top of the page.

    Thanks ahead of time!
    http://cranecams.com/master/apps/chevy44.htm#4. PowerMax

    <font color=red>GOT MUD???</font color=red>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a> [​IMG]
     

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