Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Converting my old 350 to 383; what do I need? Or, how to get more power fr

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by newyorkin, Feb 19, 2002.

  1. newyorkin

    newyorkin 1 ton status

    Joined:
    May 8, 2001
    Posts:
    16,555
    Likes Received:
    157
    Location:
    Los Estados Unitos
    Hey all. I'm about to have my '88 350 on a stand in my garage, and I was thinking I might want to convert to 383 if the block machining is minimal.
    I've been seeing a lot of 383 assembly's on ebay, and was wondering what everyone's thoughts on them are. A new 383 is $3000, while a rotating assembly for my 350 can be acquired for under $1000 (already more than I can spend..).

    Is it worth it? Should I just do a stock rebuild with whatever overbore may be needed, if my stuff is in good condition?

    Or, if 383 conversion is too much $$ and work, what should I consider to get some more torque from my 350? I don't think it's that tired, I'm swapping and rebuilding because it's developed a noisy lifter/valve/bearing, but I want more power out of it when it goes back in.
    Cam? I want a smooth idle, but power in the pedal. I'm kinda stuck with the stock heads, I think.

    Give me your thoughts, I'm starting this week I think!

    thanks!

    Ratch
    CK5 album
    Your ad here.
     
  2. muddin4fun

    muddin4fun 3/4 ton status

    Joined:
    Feb 19, 2001
    Posts:
    5,644
    Likes Received:
    0
    Location:
    N Texas
    I love my 383 [​IMG].

    "Out in Luckenbach Texas, there ain't nobody feelin no pain" Waylon Jennings 1937-2002

    <a target="_blank" href=http://www.bluefox.tv/~lara>My Wonderful Site</a>
     
  3. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    If you do all the assembling, purchasing parts and so forth, including the computer chip upgrade, intake, exhuast,......
    with the machine work and all the parts your gonna add up real quick and be well over $2000 if you wanna build a decent motor. Check out <a target="_blank" href=http://www.speedomotive.com>www.speedomotive.com</a>

    Its the popping, rumbling, roaring, twisting, flexing, grinding, so you can wheel anywhere medicine[​IMG]
     
  4. m j

    m j 1/2 ton status

    Joined:
    Dec 28, 2001
    Posts:
    4,606
    Likes Received:
    0
    how much compression can you get away with running?
    compression = power
    I wouldnt do the stroker if you have perfectly good 350 in hand.
    why throw away good crank and flywheel and balancer?
    not 100% sure but i think even the aftermarket stroker cranks require 400 damper/flywheel, though they shouldnt.
    I would build it for premium fuel with compression as high as possible.
    I am contemplating building mine to 14:1 and running propane

    formerly 77chev
    still a jerk though
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

    Joined:
    Dec 14, 2001
    Posts:
    22,059
    Likes Received:
    69
    Location:
    Pleasanton, CA.
    I have done this same exact build up myself. First off, scat makes a crank for your one piece rear seal block that is cheap, around 240.00. Depends on what other parts you use in the engine but you can use your factory front damper and rear flexplate and have it balanced internally using only 1 slug of mallory weight in the front throw of the crank. I would suggest using the 350 rods with the correct piston. you will need to clearance the bottoms of the cylinders for the extra stroke, and also the inside rod bolts because they come close to the cam. As a general rule, it is good to leave yourself a minimum clearance of .100" I have specs on the cam that i had comp cams gring for me that worked very very well. E-mail me at scotts4x4@aol.com if you would like any other info on this build up.
     
  6. newyorkin

    newyorkin 1 ton status

    Joined:
    May 8, 2001
    Posts:
    16,555
    Likes Received:
    157
    Location:
    Los Estados Unitos
    Thanks for the responses guys. I'm beat right now, and am dumping this project for a while. The temp motor ain't what it was cracked up to be!!

    I am looking to do this low-buck when I get to do it (or maybe not, but I doubt I'll be any richer by then).

    MJ, I don't know if my 350 is perfectly good or not. Right now, it'll go, but it's not as solid and powerful as a stock crate 350. If the crank is worn and I need to get a new crank or machine this one, it may be more worthwhile to spend a little more on the 400 crank/383 conversion.

    A stock rebuild is friggin expensive (around here at least), and I want more power than stock, so I'm (now) just poking around for ideas.

    Ratch
    CK5 album
    Your ad here.
     
  7. CaptCrunch

    CaptCrunch 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    3,596
    Likes Received:
    1
    Location:
    Minnesota
    well here is an idea or two to bat around as well. #1... if you aren't gonna shell out any money for cylinder heads or some major port work forget the whole thing. If your motor can't flow you aren't gonna make the power you want anyways. I'd look into some larger valve amel humps with some port work for lower costs, Dart iron eagles or World products Sportman II's if you want to keep a cast head, or else the larger AFR heads or the canfields work great. Secondly look at the EFI you have. A stock TBI unit most likely isn't gonna be enough cfm or fuel for a hauling 383. I'd recomend looking into a Holley replacement. They have 80 lb injectors and will flow about 700 cfm. And while being on injection... cam selection will be somewhat restricted.

    Overall the cheapest route may be to get a 400 long block that has been rebuilt (can be had for 1000-1500) and the Holley TBI and see how it goes. If you have problems get a chip done up from a place that will do replacements. See how you like the power and you can do a head and cam swap down the road for way more power.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     

Share This Page