Stock but not??

Discussion in 'High Performance Modifications' started by Kae450, May 15, 2019.

  1. Kae450

    Kae450 Member

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    I’ve got an 81 z28 350 4speed. Original car and I want to keep it mostly that way. Has new hooker headers. Want more hp. Can I get the engine done using the stock carb, heads and intake and get maybe another 50-100 horse?? Maybe I can just get it bored out or something? I’m no mechanic lol. Advice/opinions? Thank you
     
    Last edited: May 15, 2019
  2. jeff swisher

    jeff swisher Veteran Member

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    Bore it .030" will add 5 cubic inches.. no power to be gained really unless your rings are not sealing.
    I have been down your road many times.. poor boys you know.

    My first 350 was equipped with 624 casting heads.. I bowl ported them.. ported the iron intake manifold and tuned the Q jet carb. stuck light springs inside the distributor to make a quicker advance curve.
    I ported the 1979 exhaust manifolds I had off a caprice classic.
    I made the exhaust port taller on the heads and made the exhaust manifold ports just a little taller than the ports on the head.

    Stuck in a 268H comp cam and reused my factory weak valve springs.
    It ran 14.50 in the 1/4 mile with 3.08 peg leg rear end with 60,000 mile rated tires TH 350 trans and stock 12" converter stalled to 1200rpm.

    You are better than I was since you have a 4 speed.
    You can tweak stock parts and run very respectable.

    I later pulled the 624 casting heads which were also milled .030" to 72cc chambers. I replaced them with 186 castings that had milled to 54cc and ported them also.
    This book is very good a must have if you are capable of craftiness.
    https://books.google.com/books/about/How_to_Build_and_Modify_Chevrolet_Small.html?id=bM-86aKCS5EC

    I also upped the cam to a 270h magnum flat tappet and Z28 springs.
    It then went 13.7 et in the 1/4 mile.
    Same iron intake and exhaust manifolds and tires.
    kept breaking the 10 bolt guts.
    Stuck a 9 '' in it with 3.70 gears and went 13.02 in the 1/4.
     
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  3. Kae450

    Kae450 Member

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    Wow great information. I’d be perfectly happy somewhere in the 14’s in the quarter mile. Glad to hear that the stock parts have some potential. I can’t imagine how slow the car is to today’s standards. I’ve got an embarrassing 2016 caravan with 283hp from factory sitting out front in the driveway. Sad that it would beat my far sexier Camaro. I gotta fix that lol
     
    Last edited: May 15, 2019
  4. Evil Twin

    Evil Twin Veteran Member

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    I doubt anyone would want to run the Caravan but don't let that stop you
     
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  5. Kae450

    Kae450 Member

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    Lol like I always say, “if you drive a Caravan chicks know you put out” lol
     
  6. Zspoiler

    Zspoiler Veteran Member

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    Thats whats so great about small blocks >It doesnt take much make more horsepower.You could treat it like an NHRA Super stock engine .And with all the aftermarket and factory parts out there It depend on your budget and just how much skill you have.
     
  7. jeff swisher

    jeff swisher Veteran Member

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    That's funny :).

    You said you are no mechanic.
    Now is the time to become one. There aren't too many trusting places you can take old vehicles to have them tweaked and it will cost you a bunch of money if you do take it somewhere.

    All this stuff is not really that hard you just have to think and take some of your time to do it.
    I was porting cylinder heads before I was legal drinking age.
    Changed my first head gasket on a car before I was in high school.

    If a 13-14 year old can do it.
    Those "How to books" really pay off.
    We have internet now but there are a lot of false information deals you can get into. but some of the old books lay out false theories also.

    You kind of need to weed out the stuff which is a bit hard unless you have been there and done that.
     
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  8. Evil Twin

    Evil Twin Veteran Member

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    You could put a 125 shot on it & call it good. Easy to install and it's there if you need it.
     

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