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Flat spot

1216 Views 6 Replies 6 Participants Last post by  Zen Dog
Ever since I've had this car, it has had a flat spot during it's acceleration in 1st gear. I recently replaced the points with a Pertronix III, replaced the plugs, wires, set the timing at 10* BTDC, rebuilt the Autolite 2100 carb, installed a new throttle cable and I've plugged off the leaking headlamp vacuum system, so the system yields 18-20 in Hg. If I do not feather the gas during acceleration in 1st gear, the engine will start to die.
Any ideas?

1 - 7 of 7 Posts
Accelerator pump clogged up? or needs to be adjusted maybe.
I will check it. I don't imagine it will be since it was replaced with the carb rebuild last year. Performance seems good at all times except from a stop in 1st gear.
Could be your vac advance not functioning too....check that your line to the dizzy is good, if you suck on it it you should be able to alter the idle to test it.
Change out the shot pump Diaphram, or may have sucked up some dirt into the Carb. Did Advancing the Timing Make a Diff.? Some 289's with Miles on them require the Timing set ahead a little more advanced to run better.
After rebuilding the carb, did you check the position of the vacuum piston inside the choke housing relative to the choke plate (the paperclip trick)? This is often overlooked and if not done correctly, your choke may not be opening on accelleration.
At what point during acceleration is the flat spot? Is it immediately upon moving the throttle? How hard are you into the throttle? Does it happen in other gears?
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