Flat Spot / Throttle

I have a Dodge Polara 1964, 383 V8. Just bought it and I am addressing the main issue of the throttle.

There is a flat spot when I hit the throttle at the very beginning. I can get around this problem by slowly massaging the throttle, then once the rpms are going I can gas it to my hearts content. But this problem really gets in the way if I am at a complete stop, or need to hit the throttle quickly.

When i hit the Flat Spot and don't let off the throttle the engine dies and sputters into a stall, then the engine floods and I have to wait 20-30 minutes before trying to start again.

The engine starts up just fine if its not flooded, there's no knocking, and I just replaced (under the guidance of my 35 year mechanic father) the following:

• Spark plugs
• Spark plug cables
• Rebuilt the carb (from a shop, not me)
• Changed oil
• Changed the distributor to electric from pins
• Adjusted timing
• New battery install with new terminal wires

Any tips to what may be causing this issue? Or where to start looking?

Thank ahead of time. I am new to the classic cars world and working on cars. I luckily have a father who is a mechanic, but he hasn't worked on this model of car since they were invented

Sounds like the carb. What type and size is it? Maybe the accelerator pump is set wrong or jets are not right.

Sounds to me like the accelerator pump not working or working correctly. I'd start there.

Carb is a 2 barrel , I dont know how to tell anything else about it But i just got it brand new from the local restoration shop.

I'll take a look at the accelerator pump and tell you what I find. Thanks!

dodgepolara1964 said:

Carb is a 2 barrel , I dont know how to tell anything else about it But i just got it brand new from the local restoration shop.

I'll take a look at the accelerator pump and tell you what I find. Thanks!

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Look into the carb, give the accelerator linkage a pull and watch for a good squirt. If it just dribbles like us old guys, get a new accelerator pump. (Not blue in color)

I'm a little confused as to why the engine would be flooded under these conditions, when this occurs. By what you describe it seems to me that you're describing a momentary lean stumble. Indeed if you ease into the throttle gently off idle it can mask a stumble, or what we call a "lean hesitation". Once off-idle and the engine has gained some rpm, the carburetor transitions from the idle circuit to the main fuel circuit, and it's likely running rich enough that when the throttle is abruptly opened again, no hesitation is noticed. As stated by others, I'd sure be checking for an adequate accelerator pump shot off idle. Also don't forget to make sure your initial timing is correct (if the timing is retarded it will greatly magnify a lean stumble). But if you truly have a condition that the engine is flooding when this occurs, make sure your fuel pressure isn't too high. Also, if the carb has originally had a check ball under the accelerator pump squirter, make sure it's present. You don't mention what brand of carb it is, but if it's OEM it likely would be a Carter. I'm not sure about a '64-vintage 383-2bbl. but I know at least some of the later '60's 383-2's used them.

dodgepolara1964 said:

But i just got it brand new from the local restoration shop.

Click to expand...

THAT could easily be the main problem. Rebuilders not holding their mouth right.

Years ago, bought a 'rebuilt' carb (AFB) from a parts house. Pulled the top off, to check the float settings...and found sand-blasting material in the bowls! Think what would have happened, if I mounted it, and ran the engine.
Yeah, that carb got slammed back on the parts counter! No uncertain terms.