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Looking for more compression...

Discussion in 'The Garage' started by RustBuket, Sep 17, 2003.

  1. RustBuket

    RustBuket 1/2 ton status

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    I recently rebuilt a 305 for my '81 K5 and am already wishing I had put spent the extra money on a good 4 bolt 350 when I had started but I can't go back now. So, its a mostly stock (edelbrock intake, headers, smog stuff removed) 305 off an '84 truck. I would guess these would have about 8.5:1 compression. I am already seeking more power and know that more compression is a good way to get more power. It has the stock dished pistons (yes, I know I should have replaced those too!!! I just didn't have the cash and the cylinders/pistons were to spec so I just had them honed) Well, I don't want to rip out the entire engine again so I need something that I can bolt on with the engine in place. I was thinking maybe an Xtreme energy cam. Also, my friend suggested today that you can get your heads angle milled. He says they mill lots on the exhaust side and hardly any on the intake side so your ports still line up fairly well (may need to double gasket the intake). I was just wonderin if this would be worth it or if I should just look for some smaller CC heads? What kinda of vehicle should I look for some 64cc heads on. Remember I need the small valves because its a 305.
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    305's use 58cc chambers, you won't find anything any smaller than those.
     
  3. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    try a more agressive cam profile and maybe go to flat top pistons..............
     
  4. RustBuket

    RustBuket 1/2 ton status

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    Damn! Foiled again! Well, I guess a cam is the best I can do. Unless I can get those heads angle milled. Can anyone suggest a cam?
     
  5. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    What kind of carb?
     
  6. sled_dog

    sled_dog 1 ton status

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    I wouldn't waste the money on 305 heads, they flow like crap and allt hey haev going is compression. You could spend the same money, not have to run higher octane gas, and get the same if not better power gains with a cam. The Comp Cams 4x4 Xtreme Energy cams seem real nice. If I build a new motor for my K5 its getting one of those. And if you were gonna pull the motor apart and put in flat tops I'd say forget it and find some $50 350 block and slowly build it up. Doesn't have to be a 4 bolt, most people just go with 4 bolts cause they think its better than 2(which it is) but the real benefits are rarely seen or needed by general mild engine folks.
     
  7. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    yep,sled dog is right.The problem you have is lack of inches (cubic)and lack of compression.both equal horsepower.find a 350 and build it up over time.or at least get a set of pistons and get around 10-1 compression,with a set of good heads it might make all the power you need.In a 4x4 you want somthing with a good all around powerband.some guys think you get the biggest carb and the biggest port heads and the highest lift cam and then they cant figure out why it runs like [darn].Those motors are made to be at idle and then wide open,you have to remember you are not building a top fuel motor.Talk to members here and find out what worked for them.chances are they had to experiment to find the right combo and that gets expensive after a while....................
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Actually, the 305 makes plenty of torque. The major lack here is cylinder bore and head flow. The mid range and top end of a 305 absolutely blows. They grunt just fine for being 305 cubic inches. They just don't make any horsepower because the small bore inhibits flow and the ports suck. More compression will just make them knock because the chambers suck too.
     
  9. RustBuket

    RustBuket 1/2 ton status

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    So, basically what you're telling me is that the 305 is a peice that should never have been put in a truck? /forums/images/graemlins/1zhelp.gif Life's a biotch! I guess I'll just have to suck it up and stick a cam in it or build a 350 (which I can't see happening because I'm going to university in a year... /forums/images/graemlins/thinking.gif) Ah, w.e it'll have to wait till later.
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    No, what I'm telling you is that while the 305 runs fine, it doesn't make a whole lot of top end horsepower so your truck will never be a race truck with a 305. Because of the small bore and stuff, it doesn't respond as well to upgrades as the larger bore motors do (like the 327, 350, and 400, or hell, even the 307!)

    So, in short, leave it alone, run it til its worn out or it blows, then find a 350.
     
  11. Topdown

    Topdown 1/2 ton status

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    fersh build on a 305 can be sold locally for enough $$ to buy a decent running 350 that you can put in and slowly build on. /forums/images/graemlins/thumb.gif

    Other than that, a bigger cam will only give you so much as the heads arent exactly spectacular. I would be willing to bet you can find some good heads that will flow well, but they are going to cost you almost as much as the complete 350 rebuild.

    So, in short, either sell the fresh rebuild and use that $$ to build a 350 or leave the 305, appreciate the mileage and drive it into the ground. If your really looking for more power, try a regear of your axles, smaller tires, etc... just a thought.

    -Ryan
     
  12. SUBFAN

    SUBFAN 1/2 ton status

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    Very hard to beat pricewize the 1200 dollar crate 350....

    kind of hard to match up dollar for dollar with a rebuild....
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't know at which point they went with the higher compression 305, but a lot of the truck ones were 9.2:1 stock. May have started in '81. (too lazy to go look up the specs)

    I'm *guessing* that all 305 motors that were 9.2:1 had ESC, and IIRC, 1981 was first year of ESC in *some* trucks. (something to keep the motor from detonating to death)
     
  14. sled_dog

    sled_dog 1 ton status

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    my 84 with 305 had ESC(ripped it out with the 350). I need a bigger motor.... 383 with 4x4 Xtreme Cam is my plan.
     
  15. unick

    unick 1/2 ton status

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    forget the 350. If you are gonna build and engine build a bog block. there's ne replacment for displacement.

    /forums/images/graemlins/usaflag.gif /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif
     
  16. sled_dog

    sled_dog 1 ton status

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    yeah I know :-/ I can't find a big block real cheap. I will find one though. I'm gonna do like I said he should do, get the block and slowly build it up.
     
  17. RustBuket

    RustBuket 1/2 ton status

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    Ultimately I want a BB but I can't afford one because they don't come cheap around here and I tried selling my 305 for cheap and no one took it!
     

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