Carb Diagnosis Help Please

[kylehamilton79]

I have a '68 289 with a Motorcraft 2 barrel. I am having a significant hesitation and bogging down off the line or right when I accelerate making turns. So far I have pulled the carb off and replaced the power valve and accelerator pump and re-installed and set the idle and air/fuel mixture screws. The car starts and idles fine, and accelerates fine after that initial hesitation off the line. The engine has steady vacuum reading of 14. I am out of ideas since everything on the inside of the carb is spotless clean. I thought for sure replacing the power valve would fix the problem, and it has improved, but still almost dies on me every so often. Anyone have any pointers? This is my first time working on a carb. I need to drive the Stang this Friday to work while my truck is in the body shop so I would like it not to die in traffic. Thanks for all the help so far. Kyle

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[kalli]

hesitation usually means lean.
if the hesitation is just short during accelleratio just off idle then it usually it is not enough pump shot.
If you drive off a stop and hold the throtlle only the slightest bit on accelleration position and keep it there (not changing the position) and the car keeps hesitating and jumping then I'd say it's the float level too low.

[69mach1377]

Not enough barrels

[kylehamilton79]

I know I need a couple extra barrels. This winter I plan on adding an Edelbrock Performer intake and carb. Thanks for the help Kalli. I will try and check the float level or find someone that knows the correct way to check it.

[fishkg]

I had the same problem. In addition, if I drove it at a constant speed for a few minutes, and then gave it gas sharply, it coughed as well. From a dead stop it just sat there until it quit choking. I tried everything that you have, and float adjustment too.

Finally solved it by swapping to a Weiand manifold and Edelbrock 4-bbl. It still just sits there if I floor it from a dead stop, but only till the tires quit smoking and catch. :-}

Check to make sure both barrels are getting the same amount of spray when the accel pump works. I didn't notice mine was weak on one side untill I was messing with it after it was off.

[kalli]

there's a document about the motorcraft 2150/Autolite 2100

http://www.therangerstation.com/tech..._2150_carb.pdf

but before you try adjusting the floats, check on the accellerator pump first.
get rid of aircleaner and with motor off open the throttle plate (accellerrate fully) while looking down the carb. you should see a healthy spray of petrol going down the carb on both sides. if that's all ok try adjusing the linkage for the accellerator pump so that it sprays even more and see if that helps (there's 3 holes to choose from if I remember correctly).

as I said earlier there's differences in just off idle bogs but probably only can tell apart once you had both situations. one is caused by the accellerator pump (not enough pump shot). that can usually reproduced at all rpm ranges, as soon as you mash the pedal you get a stumble. then the car moves. usually the worst just off idle. that's most likely caused by accellerator pump.
If the car behaves in such a way that you drive off a stop but only tip the accellerator (so you would drive very slow) and while holding the accellerator in that position it bogs/stumbles. but as soon as you put the foot a bit further down it's back to normal, that is usually caused by float level too low

[kylehamilton79]

I worked on the carb a little more yesterday and adjusted the accelerator pump linkage position. It was originally in the top hole and I moved it down one hole. That seemed to help some. I believe there are 2 more holes, so I may try moving it one more down to see if that cures my hesistation. I did drive the Mustang to work this morning and it ran pretty good, even with freezing temperatures. I just hate having to ease into the throttle. I like going fast. An exhaust shop owner that is a friend of mine said to check the timing, distributor and points. He said if its not advanced enough it could cause a stumble off the line.

By the way kalli, I've had that link about rebuilding a ford carb saved on my computer for a long time. It has really helped me when I disassemble and put mine back together. Thanks for the help. All I gotta do is get the car running better and then I'll be off to get some new exhaust.

[kalli]

best off luck ... your friend is 100% correct. ignmition has to be donme before the carb. I just assumed that this is all ok since the post is about carbs.

[69mach1377]

Did you say points?
Is this a show car or a go car?
Please accept my tough love in a positive manner...