RPMs Jumping

66 GTO · 10-31-2007, 01:43 AM

I have a 66 gto with a 69 400ci 4 speed. The car has always ran really strong but all of a sudden one day i was driving a little faster than normal and i noticed in 1-3rd gear at around 3500-3600rpm the car would begin to jerk and the rpms would radically bounce around until i shifted to the next gear. Soon the car began to do this in every rpm, even when i take of slow so i replaced the points but the problem still persists it just keeps getting worse, the car jerks and the rpm,s bounce around all the time and the more u drive it the worse it gets, sometimes you can make it past the lower rpms without it jerking but it will always do it at around 3500rpm. i have replaced the distributor put new points in it put on a new ballast resister and checked the plugs and wires it already had a new coil and fuel filter. could someone please help me out im out of ideas

svede1212 · 11-03-2007, 02:41 PM

bucking can be fueling or timing. i'm so used to new school and logging engine parameters that i can't be of much more use than that but it's one of those. sorry i can't help more

05GTO · 11-03-2007, 08:33 PM

Check the points gap, dwell and timing, may also be a problem with the vacuum advance. I replaced the points and condenser in both of my GTOs with the Crane XR-i Points-To-Electronic Ignition Conversion Kit. This kit also eliminates the need for a ballast resistor and has a rev limiter.

Good luck,