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how to add horsepower

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zach78k5, Nov 2, 2004.

  1. zach78k5

    zach78k5 1/2 ton status

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    I have a 305 with headers, holley projection and k&n filter system. What else can I do to add a reasonable performance gain. I was thinking HO heads, or maybe roller rockers. The nice thing about the rockers is that when I go to a 350, they will go accross. that is nice but not crucial. I thought about a cam, but since the engine is used I don't know if a cam will do much for me.
     
  2. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    put a blower on it /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    Good aluminum manifold, quality exhaust system, cold air intake. Other then that I would say good ignition system. Good wires and quality parts in the distributor and good plugs.

    Before I did a cam swap I would do a good set of heads. The projection probably won't like a cam unless it isn't to wild.

    Harley
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Put a 350 in it. /forums/images/graemlins/thumb.gif
     
  5. ratzila

    ratzila 1/2 ton status

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    Scrap the 305 and put in a big block /forums/images/graemlins/thumb.gif
     
  6. mudslinger97116

    mudslinger97116 1/2 ton status

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    NOS.. /forums/images/graemlins/grin.gif i don't know if it will work with your projection though? i have one of the old style projection and it's only capable of like 275 horse
     
  7. k5redneck

    k5redneck 1/2 ton status

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    [ QUOTE ]
    Scrap the 305 and put in a big block /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    thats the best way to add horsepower /forums/images/graemlins/peace.gif
     
  8. backcountry

    backcountry 1/2 ton status

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    MSD spark box, distributor and wires will give you some gains.

    A cam will do wonders, however you will need to change the lifters and timing chain/gears. This will make a bigger difference than the money spent on roller rockers by far.

    A good set of heads with at least a three angle valve job, swirl polished valves with undercut stems and a little porting will also do wonders.

    Depending on how many miles you have on the motor; if you perform too many mods without lower end work you will run into problems.

    /forums/images/graemlins/peace.gif
     
  9. tomseviltwin

    tomseviltwin 1/2 ton status

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    502 ram jet
     
  10. Muddytazz

    Muddytazz 1 ton status

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    add a couple more hampsters /forums/images/graemlins/dunno.gif
     
  11. stallion85

    stallion85 1/2 ton status

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    I got 10 extra horsepower when I put this bad boy on. It only took me 2 minutes install time too /forums/images/graemlins/grin.gif
    [​IMG]
     
  12. elacruze

    elacruze 1/2 ton status

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    Consider your requirements carefully, rpm vs. torque, etc. 305 heads on a 350 are a secret torque weapon. If I were building a 305 for a truck I'd carefully choose a cam for it-I had a 305 in my '85 GMC K15 and with high axle ratios, it didn't work well with even an RV/towing cam. It needed a torque converter change to work right. With the intake and headers already on it, I'd save the money and get a 350, or an old 400 if you can find one. The 400's are real monsters with the right stuff, and their overheating problems are mostly circle track issues. You can find them cheap if you live far enough away from the local dirt track, and I've never ever seen a 400 break anything unless it ran out of oil. They have great big bearings.
     
  13. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    Consider your requirements carefully, rpm vs. torque, etc. 305 heads on a 350 are a secret torque weapon.

    [/ QUOTE ]

    Nonsense. This is a myth. 305 heads flow like crap. They won't offer a gain on any 350 at any RPM.
     
  14. zach78k5

    zach78k5 1/2 ton status

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    As I said, a 350 is in the future, but not immediate. maybe next summer. my drawback of the cam is that i cant put it into the 350. the MSD box, roller rockers or a torque converter would all be useful with the 350 as well i suppose. will the ignition box be worth while? should I change the ESC distributor over to HEI first?
     
  15. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Real world what I do with my 305 for better performance , is to religiously change my oil and filters every 3000 miles , a complete tune up each year , and try to run higher octane when I can afford it . Lower gears help too , a LOT . When I had the 3.08's and 33's it actually worked OK , but going lower on the same size tire really woke it up a hell of a lot ( although I rarely get on it , lost license before , not again I'm mature now /forums/images/graemlins/ignore.gif ) . So I just reccomend easy bolt ons like you have and be happy with it until you can get a XXX size smallblock and transfer that stuff over . /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif
     
  16. blazd88

    blazd88 1/2 ton status

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    vortec heads! iv built roughly 300 pair of these for Scoggin-Dickey here in Lubbock and they make a huge difference(stock or not). Look into part #8060ra. They have bigger valves,springs, cut guides, and bigger push rod holes. /forums/images/graemlins/waytogo.gif
     
  17. zach78k5

    zach78k5 1/2 ton status

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    can I put 350 vortec heads on a 305?
     
  18. df

    df Registered Member

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    Just dropped a GM crate 350 290 HP into an 85. Transfered most everything over. Very significant power gain for $1580.00 performance engine.
     
  19. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    my drawback of the cam is that i cant put it into the 350.

    [/ QUOTE ]

    Why can't you?

    [ QUOTE ]
    can I put 350 vortec heads on a 305?

    [/ QUOTE ]

    Absolutely.
     
  20. zach78k5

    zach78k5 1/2 ton status

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    that is good to know. someone told me that 350 heads would not work on a 305. I know i can pick up vortec heads for a pretty reasonable price.
     

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