1970 RS Z28. Running a factory LT1

Discussion in 'Troubleshooting & Diagnosis' started by harkz28, Nov 19, 2017.

  1. ronzz572

    ronzz572 Veteran Member Lifetime Gold Member

    Feb 8, 2007
    imperial pa
    I would check the fuel pump pressure the carb float levels just to clear them as the source 1st. Is it a misfire surge as a jerking sensation surge? Or a lack of fuel where it goes flat, Boggs down and looses power and surges back. Identifying what type of surge may help you get a answer as to where to start.
    Last edited: Nov 20, 2017
  2. harkz28

    harkz28 New Member

    Aug 22, 2005
  3. hogg

    hogg Veteran Member

    Dec 29, 2000
    Check your gas cap,make sure it is vented. Also i had a rubber hose at tank that was week and would stop up the line when runging hard.
  4. COPO

    COPO Veteran Member Lifetime Gold Member

    Sep 15, 1999
    Ontario, Canada
    With today's gas you need to change the rubber lines to fuel injection rubber.
    SRGN likes this.
  5. harkz28

    harkz28 New Member

    Aug 22, 2005
    Adjusting the spark plug gap .40 seems to as hell have helped. Next Step Up with the Jets in the carburetor
  6. SRGN

    SRGN Veteran Member

    Feb 20, 2009
    Central NJ
    Solid advice. If the lines are old and deteriorating, they may allow the fuel pump to draw in air without allowing fuel to leak out as well. Or even collapse if you're in a high fuel demand situation. Regardless, a good idea to change them.
  7. Tphil413

    Tphil413 Veteran Member

    Jun 1, 2007
    San Francisco, CA
    I'd check your fuel filter. I experienced the same surging once when my fuel filter was partially plugged, dirty. Didn't show up at slow speeds but at freeway speed when I accelerated.
  8. 2ndGenCrazy

    2ndGenCrazy Veteran Member

    Aug 18, 2011
    Upstate New York
    There is one thing that I always do in the course tuning a customers car.
    In order to determine the correct power valve for a street driven car, I do the following:
    I Install a vacuum gauge connected to full manifold vacuum using a long hose so that I can read it while driving the car.
    I then drive at various speeds and loads to ensure that the power valve will stay closed during normal low speed cruise conditions. If it is on the threshold of opening at a cruise point, it may open and close repeatedly, or "dither" causing a surge.
    This is just one thing to look at along with other good comments posted.
    I would select a rating 2" HG lower than the lowest value seen during the cruise test.

Share This Page