Have a Flat Spot in Acceleration

[AFB]

on my 69 Coronet with 440 and 4 speed. At low speeds (1000 RPM or less), if I try to gradually, smoothly, accelerate (as in leaving a traffic light or just keeping with traffic), it hesitates before speeding up. Car has a Pertronix module in the factory distributor, Edelbrock (AFB) carb (new) and is completely stock. I'm wondering if this could be a timing issue? I did mess with the vacuum advance a lot before giving up and installing the Pertronix. If I really punch it, it accelerates fine with no hesitation. It does not surge while cruising. Not sure, but I think the timing is at TDC. Also, I must confess the smoothness of the throttle linkage has not been checked. Sorry for all the rambling............I'm just looking for experiences and recommendations from the forum...........tx..........james

 

[Meep-Meep]

Assuming your accelerator pump is working then it could possibly be a timing issue. I never ran a MoPar at TDC, so you may want to look at advancing it a bit. Dist vacuum should go to the ported port on the carb and your mech advance weights should move freely and spring back consistently. Check the advance curve with a light and make sure you have smooth advance action up to about 2500 RPM.

 

[AFB]

When I said I "messed with the vacuum advance", I should have said I used a small allen wrench to change the setting of the tension on the diaphram. Also, that's a good point on checking the accelerator pump, I "assumed" it was working since the carb is new, but I'll check to make sure...........tx for the reply........james

 

[Manifold]

Definitely get the timing in the BTDC zone. You can start off with something conservative, like 12* BTDC. I prefer to use a vacuum gauge to set my timing, but using 12* as a starting point will at least show you whether or not changing the base timing will have an effect on your issue. If you're at TDC, then I'm betting it will help/eliminate your problem.