I own a "68" Mustang with 302 J code 4brl. that is 99% orig. After rebuilding the autolite mod 4300 carb., setting the timing, adjusting the carb., replacing all vacuum lines, and replacing fuel filter I am getting a bog down when I punch the accelerator. Does any one have any ideas of what I can do to eliminate this accelerator bog? George1

 

Did it do that before? If not then it's a timing issue. That's provided everything is working properly. Otherwise it's prolly the accelerator pump shot.

 

Definitely check the timing first. Try it at 8-10* advance at idle with the vacuum advance unplugged and the line capped. If that doesn't work, try adjusting the accelerator pump to pump more fuel. I can't recall which direction you have to move the linkage, but it shouldn't be hard to figure out looking at it.

 

Thanks for the helpful hints, Ill give those ideas a shot. Geo Out[:@]

 

Sounds like the timing is a little off![sm=signs003.gif]

[IMG]local://upfiles/72436/5AC59AC1F6514DE78925D150A360F3B5.jpg[/IMG]

 

I would like to add that when setting the timming we used the spec found in the fomoco man. for 68 must/cougar- 6 degrees btdc @ 550rpm. What would tweaking this setting one way or the do for accelleration?

 

Increasing the advance will improve acceleration and throttle response, to a certain extent. That's why I recommended 8-10* at idle; most stock sbf's like those numbers better. Retarded timing can cause hesitations just like you're describing. I still suspect your accelerator pump may need to be adjusted, but kicking the timing up will likely help.

 

Thanks again for your advice. We will be doing some fine tuning today with your recomendations at hand. Awsome, talk to you later.

 

check on choke plate. is this a carb with manual, thermo or elkectric choke ?
when engine is warm the choke plate should be fully open.
with engine off look down the carburator and when acceleerating fully you should see petrol shooting down the carb
if that happens you know that the accel pump at least kinda works

 

I believe it is a thermo choke, whatever the original setup was, with the tube coming up from the manifold, but we did adjust that to spec. We also adjusted the timing forward to approx. 8 bdc, which helped but we are still getting a carb. bog down when you punch the accelerator. We were wondering if resizing the jets in the primary would help. Either, larger orsmaller? We also tried all three settings on the acceleratorpump linkage - we chose the one that worked the best, I believe it was the middle setting. Also, we adjusted the carb. linkage so that the4bl would work properly. Thanks for any advice, George1