After rebuilding this carb, setting the float, adj. auto. choke, setting the dwell and points, setting the timing slightly adv. to approx. 8*btc, adjusting the accel. pump linkage, of course new plugs and wires I am still getting an accelerater bog when I punch the pedal. I am leaning toward resizing the jets or the accelerater pump diaphram. I have had some great advice so far. Has anyone experienced anything like this or have any further suggestions?

 

It sounds like the accelerater pump diaphram may be leaking. If its never been replaced, then it needs it. Make sure its linkage is OK. When it squirts fuel, and the timing is right, then it will go.

 

another thing is to check the vacuum advance on the distributor.
for this make sure the hose from carb to that advance is ok (no leaks). can be tested with taking it out, closing one end and sucking on the other.
The same thing you do with the diaphragm. basically connect that hose to the vacuum advance and take that piece that was connected to the carb into your mouth (if you don't have a vacuum pump). when you suck on it it should get harder and harder and when it stops block the hose with your tongue. the pressure should hold. if it eases off to no vacuum again, then the vacuum advance in distributor is shot.
If it holds it, then that's good news. but i never seen a car older than 20 years with that thing still working without replacing.
If it still works you can do a quick check as well to see if it's hooked up correctly.
Get rid of diustributor cap and rotor. When you suck on the hose connected to vac advance you should see the contact breaker plate moving towards you (turning). when you block the hose with tounge it should stay in position until you release ....

good luck ...

Kalli

 

Weren't 4300s notorious for poor performance from the factory. sounds like a timing thing. at idle 289s seem to like around 12btc. remove the vacume from thedizzyand plug it. advance it to where the eingine runs best then drive it and and if it pings retard it just the slightest. see if that helps.
Kip

 

Yea, I think you are right,,,, the 4100 was the good one... the 4300 was a "smogger carb" first introduced in the 70s right?

http://www.ponycarburetors.com/defau...s#autolite4300

Here is some information from Pony Carbs that kind of indicate that even if you have rebuilt the carb "right" you will have issues...

The Autolite 4300 in one of our very special products. From day-one they all had engineering problems. In driveability those problems amounted to hesitations and flat spots on light acceleration, a big bog on hard acceleration, and hard starting when hot.

Any of this sound familiar?

Welcome to the forum George!

 

Thanks for all the advice. The thing runs great other than the big bog on hard acceleration. I am going to check out the vac adv and the acc pump diaphram. What do you suggest to do about the fuel leakage around the seams? Thanks again for all your helpGeorge1

 

The 4300 was first used in 67 on non-hipo 289's. Definitely inferior to the 4100. Personally, I'd try to find a rebuildable 4100 and use that