Help! Vibration under rpms in a 69 302 .Anyone? Bueller? Bueller??

Discussion in 'Classic Mustang Specific Tech' started by The Hopkinator, Dec 8, 2003.


  1. The Hopkinator

    The Hopkinator New Member

    Joined:
    Dec 6, 2002
    Messages:
    146
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    NC
    The wifes 69 Fastback ( I hate the sportsroof thing) , has a mild vibration under rpms up until about 5,000 . The engine is a rebuilt 302, with a mild cam. It did it before AND after the rebuild. We thought maybe the harm. balancer. Nope. The crank was balanced out. The fan is new, and spins steady. Its the original 69 302. Ive heard that some of the old 302s and 351s will do this, and only God can make it stop,even after a rebuild. Maybe if we make it an "Eleanor",,OKAY GAH IM JUST KIDDING !! :rlaugh: Anyway, anyone ever run into this kinda deal. It gives a nice back massage while around 2500 rpms, but its rather annoying overall. :shrug:
    #1
  2. 6Stang7

    6Stang7 New Member

    Joined:
    Jun 1, 2003
    Messages:
    1,564
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Livermore, CA
    Well, first off are you sure it's from the engine? If you ran it up to 5k, then shifted dropping the rpm back down, would it come back? How bad is it? What condition is the carb in? What is your exhaust set up? Some ideas that I have is that your carb is out of tune, causing your engine to shake (improper float levels will cause this), or that your flywheel is unbalanced; although I would figure that it would get worst and worst the higher your rpm, but you say it cuts out at 5k.

    -Shaun
    #2
  3. pabear89

    pabear89 Active Member

    Joined:
    Apr 16, 2003
    Messages:
    2,126
    Likes Received:
    0
    Trophy Points:
    46
    Location:
    High in the Hills of So Ca with the Voices in My H
    What shape is the dist in?
    could be loose bearing or breaker plate bushings.
    Does this happen in netural or while driving?

    PB
    #3
  4. SuperDave

    SuperDave Early-Model Mentor Founding Member

    Joined:
    May 3, 2000
    Messages:
    6,362
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Tacoma, WA USA
    You might also check the torque converter for tightness.
    #4
  5. zookeeper

    zookeeper Founding Member

    Joined:
    Aug 25, 2001
    Messages:
    3,169
    Likes Received:
    3
    Trophy Points:
    59
    Location:
    Northern California
    Does it do it under power or at rest? If only under power, chech your driveshaft and U-joints. This is NOT inherent to small block Fords, whoever told you that was wrong. When you say you had the crank balanced, I assume you mean crank, rods, pistons rings, bearings, balancer, etc. It's cheap insurance to have the whole thing balanced while it's apart just to avoid the situation your facing now.
    #5

Share This Page