Is my car running what it should? Engine build thoughts?

Discussion in 'High Performance Modifications' started by Jhboy10, Sep 14, 2020.

  1. Jhboy10

    Jhboy10 New Member

    Messages:
    15
    Likes Received:
    2
    Joined:
    Nov 19, 2014
    Location:
    Rabun County,GA
    I dont have a set goal as far as ET. I would like to get the most of what I have with small tweaks. I dont want any more cruising rpms for just a couple of tenths. I guess I just want to tune it in right more than change big things.
     
    Last edited: Oct 17, 2020
  2. Jhboy10

    Jhboy10 New Member

    Messages:
    15
    Likes Received:
    2
    Joined:
    Nov 19, 2014
    Location:
    Rabun County,GA
    Since posting I have added a Rpm Airgap and a aluminum radiator. I turned the timing down to 32 degrees. Also, I got an AFR gauge and it shows 9s and 10s rich at WOT. I decreased the secondary jets a few sizes till they are lower than the primaries. I got to run the other night and ran 13.4 at 100. I think if I can get the carb figured out I'll be happy with it.
     
  3. biker

    biker Veteran Member

    Messages:
    2,170
    Likes Received:
    798
    Joined:
    Dec 7, 2014
    Location:
    Canada
    Pretty respectable time and speed! Your total timing might be a bit low, I'd try 34 and run it again.
     
  4. Robert stuart Bell

    Robert stuart Bell Rsb78LT

    Messages:
    65
    Likes Received:
    13
    Joined:
    Jan 21, 2017
    get another carb for the track, one of my old boss's had a s10 with a 383 and he was running a 1000cfm demon that would push his truck to a 12.7. I wouldnt recommend a 1000cfm carb as his motor liked to eat intake gaskets and belts but something from 750-850cfm should be a healthy improvement
     
  5. 1980RS

    1980RS Veteran Member

    Messages:
    4,591
    Likes Received:
    1,301
    Joined:
    Jun 17, 2006
    Location:
    MN
    Not always true, I ran my 358 pump gas SBC with both the 850 and 1000 demons and they were within a hundredth of each other @ 11.30's
     
  6. Robert stuart Bell

    Robert stuart Bell Rsb78LT

    Messages:
    65
    Likes Received:
    13
    Joined:
    Jan 21, 2017
    while that is true, thats generally what happens when you oversize the carb. 1000cfm is too big for most small blocks. but 670 is too small for a 383 to fully breathe, I mean hell I'm running a 600cfm holley on my 305 and it wants more
     
  7. 2ndGenCrazy

    2ndGenCrazy Veteran Member

    Messages:
    774
    Likes Received:
    45
    Joined:
    Aug 18, 2011
    Location:
    Upstate New York
    Comp 292 hydraulic flat tappet
     
  8. biker

    biker Veteran Member

    Messages:
    2,170
    Likes Received:
    798
    Joined:
    Dec 7, 2014
    Location:
    Canada
    Thanks. Good numbers!
     
  9. G72Zed

    G72Zed Veteran Member

    Messages:
    1,947
    Likes Received:
    790
    Joined:
    Sep 8, 2015
    Location:
    Canada
    Have seen the same thing many times as 1980RS, and the smaller carb provided better throttle response in corner transitions and overall driving manners.


    In my experience and observations, the engine moves & generally requires around 1.3 to 1.4 CFM per observed HP (+/- pending combo). The carbs rating, boosters and overall design & spacer combo's used are more or less dictated by the engines intake design.

    Judging by the OP MPH, and assuming a typical 3550# weight, the OP is in the 355hp range, 670cfm is more than enough to feed this engine...but on a dual plane with fully divided plenum, I will agree, more carb CFM would be needed in that application.
     
  10. Robert stuart Bell

    Robert stuart Bell Rsb78LT

    Messages:
    65
    Likes Received:
    13
    Joined:
    Jan 21, 2017
    why I mentioned getting a carb just for the track, a 670 will have better street manners and economy but if you just want the best E.T. I'd throw any 850cfm holley drag race ready carb on it
     
    camaro71/holland likes this.

Share This Page