ok. i have a 1968 ford mustang with a 289/c4 combo. basically stock. as long as i can remember the car always bogged down and shut off when floored from idle (stop). i tried different carbs and still the same thing. i am currently running a new 600 cfm holley single feed with vac. secondaries. the car seems to run great and just bogs upon flooring it from a standstill.

i have tried so much and am puzzled by this. could anyone help please? thank you.

 

have you checked timing?

Does it come off the line great then bog down then die? if yes fuel pump

Check for vac leaks?

-Gun

 

i've tried to check the timing but my a/c and brackets are in the way of an already dirty bottom end. i guess i could have it professionally done. i assume that when you can start a car without cranking over too much that its in time. it starts right away, but it couldn't hurt to check.

the car instantly bogs by the way. as soon as i floor it, it bogs terribly and picks up great if it doesn't cut out fisrt.

how could i check vacuum leaks?

 

Spray carb cleaner around the carb. If the idle changes there is a vac. leak.

 

Sounds like a mix problem...low speed circuit. You probably need to adjust your idle mix screws.

-Gun

 

Sounds to me like a its bogging due to a rich condition (carb is introducing too much fuel during acceleration), but its confusing that the problem occurs with different carbs. What do your plugs look like?

Also, I'm assuming that the car is warm when the problem is (still) happening? My motorcycle used to have a similar problem when the operator (me) would forget to take the choke off after it was warm...

Gun has it right to suggest getting the timing checked out first... Does your distributor vacuum advance?

Good luck.

 

i'll check the plugs as soon as i can. last time i checked they looked fine.

my distributor does have a vacuum advance.

the car is warm when this happens, but i know that the chocke is not on when i attempt this.

 

sounds like its not advancing properly when under a heavy load. could it possibly be a faulty vacum advance in the dizzy?

 

Other than changing the carbs out, what have you done to the car? How many and what kind of carbs did you try? Did you try messing with the accelerator pump on any of these carbs? Did the carbs that you have tried come off of good running vehicles, or the back of someones garage? When you say a new 600, new to you or new out of the box? Lets get some information on this.

 

this is what i started to lean towards after talking to people. it makes sense because it drives fine except when i floor it off the line or let off the gas rollin down the highway and press the gas to pick back up to speed (say coming out of a turn when i let off the gas, deccelerate, and press the gas to pick up again)

i've had a holley 380 cfm (came on the car), just replaced it with a holley 670 street avenger i had laying in the garage (brand new out of the box), and recently just put this brand new (out of the box) holley 600 cfm on the car.

i did play around with accelerator pump cams and nozzles and the shot itself on the street avenger. it seemed to help but ultimately under load it did the same thing.

other than the carb, i really haven't done anything (motor wise) to the car except maintain it and give it tune ups. i admit i did mess with the timing a long time ago, but i tried to oput it back as close as i could.

this week i will have the timing checked and check into the load thing.

again, you think i should try a new distributor or not? thanks.