Holley carb Q

Hey guys.

This is for my 1980 351M Bronco, but I know you boys know what you're talking about, so....

My Q is that one day my Bronc ran fine, the next day, a POS and would just constantly stall with lots of black smoke WOT.

I went straight to the carb (4160) and checked the floats and the secondaries were just gushing gas. My question is how? What happened that they would do this? The lock screw was tight and the day before it ran perfectly.

So I leaned it out big time - about a full turn on the nut - and it runs good, but still blows a little black WOT.

Any thoughts on this... I swear, the float screws were tight. Why would it just flood out like this???

This truck gets 10mpg on a good day. I fear I am down to 7 or 8 now until I can get the carb set right...

Thanks all!

Brad

Reply to
Brad and Mia
Loading thread data ...

Probably because that float became saturated, and now is heavier, or there was a spec of dirt in the needle & seat. You didn't lean it out, you just lowered the float level a little bit. The proper way to adjust the floats is to remove the screw on the side of the bowl, and turn the nut untill gas just starts to run out the hole. I would pull the bowl and metering block and clean them real good, and shake the float to see if any gas has entered it. If it has, then replace the float. Then check the float level.If you still suspect it of running rich after properly adjusting the floats, you need to pull a spark plug to verify it. If it is, then you will need to change jets. If it's the secondaries that you suspect, then you need run it wide open, or at least untill the secondaries are open for a little bit then shut it off without lowering the rpms to get a true reading on the spark plug. Then you would change the rear jets accordingly. If you suspect the primaries, then you would just let it idle for a few minutes and then shut it off, then pull a plug. You would then change the front jets accordingly. I suggest when changing the jets to go 2 sizes at a time till you get the desired results.

Gary

"Brad and Mia" wrote in a message:

Reply to
GEB

Check the power valve. It is probably busted.

Erich BTDT on a 83 F250

This is for my 1980 351M Bronco, but I know you boys know what you're talking about, so....

My Q is that one day my Bronc ran fine, the next day, a POS and would just constantly stall with lots of black smoke WOT.

I went straight to the carb (4160) and checked the floats and the secondaries were just gushing gas. My question is how? What happened that they would do this? The lock screw was tight and the day before it ran perfectly.

So I leaned it out big time - about a full turn on the nut - and it runs good, but still blows a little black WOT.

Any thoughts on this... I swear, the float screws were tight. Why would it just flood out like this???

This truck gets 10mpg on a good day. I fear I am down to 7 or 8 now until I can get the carb set right...

Thanks all!

Brad

Reply to
Kathy and Erich Coiner

Thanks Gary. I fear dirt in the needle/seat too. I had run the gas tank pretty low that day and the tank probably has crud in it after 25 years. Thanks again for the advice on a fix!

Brad

Reply to
Brad and Mia

Yip, that is another thing I will check. Thanks Erich.

Brad

Reply to
Brad and Mia

Oh, BTW, is the needle/seat an easy pull? Seems just like one screw???

Brad

Reply to
Brad and Mia

The suggestion about the power valve is probably good. Also, the needle and seat assembly has a o-ring on it. If it is tired and worn gas will push past it from the fuel inlet directly into the bowl causing flooding. (The needle and seat assembly is actually what you are raising/lowering when you turn the adjusting nut.) Holley's rebuild kit is only about $25, includes new needle and seat assembly, gaskets, power valve, accelerator pump diaphragm, check balls, etc. No jets, though.

If the old gaskets stick when you disassemble the carb, 95% rubbling alcohol will soften them up for easier scraping.

Gary H

66 GT

about, so....

constantly stall with lots of black smoke WOT.

were just gushing gas. My question is how? What happened that they would do this? The lock screw was tight and the day before it ran perfectly.

but still blows a little black WOT.

flood out like this???

get the carb set right...

Reply to
billydoff

Thanks! I really appreciate you taking the time to share your knowledge. :)

Brad

Reply to
Brad and Mia

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.