i have a 86 bronco with the 4.9l 4spd i just purchased for $450 cause the carb. needed to be rebuilt but the guy didnt want to deal with it. he sold it without the carb at first but i had an extra sitting around from a 78 4.9l so i threw it on to see how it ran. it ran good so then the next day the guy got the original carb back and it was needed new gaskets but i just put permatex around it to see how it ran with that carb. it ran good but when i would drive it it would only go so fast then you would really feel it bogg down. if i would push on the gas so slow it will feel like it is doing fine then after a certain point it would bogg down. if im in 2nd i would have it floored and take me like 5 sec to get up to 25mph and it would be screaming. the carb from the 78 is a motor craft and i just rebuilt it and cleaned it yesterday and it still bogs down. the original carb i got with the truck is an autolite and could not find a kit for it or i would have rebuilt that one.


now the 78 carb also had the vaccum output for the distributor so i just plugged it cause the ingition is the duraspark one that came after that vaccum on the dis.

why would it bogg down do much? i also havent gotten past 45 yet cause it takes so long.

 

Originally, 1984-1986 engines have what is called the feed-back system. The carburetor and ignition timing are controlled by the computor. If any part of the system is inoperative, the computor goes into a "safe" or "limp home" mode. That means that the timing is locked at something like 10 degrees and the carburetor goes very rich.