I have a 71 f100, I believe it's a 360 and has a holley carb 4160 on it. It was driving fine and started getting a little choppy and stalled. Will fire up but won't stay running. There is gas leaking out of the diaphragm housing. Every year I have to take the carb apart and it's becoming a hassle. I need to fix this asap as this is my daily driver.
I'm mechanically inclined but do not know much about carbs except buying a rebuild kit and installing it.
What can I look at to fix this issue, should I just rebuild it again? I've looked the issue up but get a little lost.
I'd like to eventually change the carb to a different one that's more reliable, possibly with electric choke. How do I choose the right carb that will fit? Any suggestions? I know some guys favor edelbrock or holley and vice-versa.
Apologize for the long read, I just need to get this thing going for right now and before I get into it wanted to post this beforehand, instead of later.
Any suggestions/pointers/advice helps.

 

The accelerator pump diaphragm is an easy fix. Why are you taking it apart every year ? I've got three Holley 2 bbls on a 15 year old engine and have yet to take them apart after all that time. What ignition are you running ? If it's points, that's half your problem, not the carb. 90% of carb problems while running points ignition are due to the points wearing, not something with the carb. The other carb problems are usually related to fuel quality, or not running a filter in the fuel line. If either of these two issues aren't addressed, you will continue to have problems with an Edelbrock carb.

 

If you are changing the diaphragm that often, I'd suspect you aren't staying away from ethanol like you should be. Otherwise yes, you need a fuel filter (issues with sediment and pieces of hose also compounded by ethanol, btw...).

Also, are you only driving this vehicle for a month of the year and leaving old gas in it? Put some sta-bil in the gas.

In any case, you are chasing something you are doing to yourself, most likely.

 

I drive the truck daily 70 to 80 miles. It looks like the secondary are flooding. The fuel is leaking out the sides and out of the diaphragm. There is a in-line filter on the fuel line. I'm not staying away from ethanol, I run regular gas not premium. I might change that if I have to.
I have a rebuild kit coming, already have it apart and cleaning It, just going to throw the kit on it and see how I make out.
It's a 4 barrel carb. 1460 600cfm. Auto-adjusted floats which I'm not sure I like or not.
I might throw a different carb on it soon, just not sure which one I'm going to go with.

 

Changing to ethanol free gas will probably get rid of your issues. That stuff eats away at rubber in no time. There is a green diaphragm for use with alcohol that I'd look into and any other rubber hose you have needs changed if you want to continue using ethanol (including the filler neck and vent hose).

Auto adjust floats?

 

Yea, some of the emissions Holleys have non adjustable floats. His secondaries have probably never opened up either, further causing issues with stagnant fuel in the bowl eating it up. I run a mix of 91 conventional premium and 93 E10 in my Comet's Holleys, alternating between fillups, this has kept them happy for all these years, keeping the ethanol content down below 5%.

 

The ratio of ethanol has nothing to do with the grade of fuel (regular vs premium) Your secondaries are flooding because they've likely never been opened up enough to keep the fuel in them fresh, letting the ethanol do it's destruction. You'd do better with a 2 bbl carb in this regard, eliminating the extra side and it's parts that don't get used. If you did decide to rebuild it, get a secondary spring kit and install the lightest spring in the vacuum pod so that this side gets used more often to keep the fuel fresh and flushed out.

 

The fuel in the secondary side of a 4 bbl is kept fresh by the fact that the carburetor idles off of the secondaries as well, or should when tuned properly.

The ethanol content certainly can have to do with the grade of fuel depending on where you are and what stations are at your disposal. Some here have 87 reg, 87 ethanol blend, 91 in either regular or ethanol. Others have 87 ethanol only and 91 regular. It's a total crap shoot.

Edit: poor wording. "Tuned properly" doesn't mean anything special in this case. It just means "not shut off entirely." Unless you have closed off the secondary float entirely, you are getting emulsion through the idle port on that circuit.

 

Are they actually auto-adjusting or are they just non-adjustable?

9/10 for me a flood is just from a piece of something (usually a tiny flake or rust or rubber) holding the needle up. The fuel filter should catch basically any rust flakes but every time you take a float bowl or the rubber feed hose off and put it back on you have a good shot at o-ring or hose getting in.

 

I beg to differ. I hauled gasoline. E10 is E10 no matter the grade. What is posted on the pump as far as ethanol content is fixed in stone at the loading rack. our 93 octane premium is 91 octane conventional with ethanol added to it to bring up the octane. 87 conventional can have up to 5% ethanol in it. 87 E10 is a lower grade of regular gas, like 85 octane with ethanol mixed into it to bring up the octane. It's not a crap shoot. What octane is posted is what it is by law. So is the ethanol content. Now, different regions can have different blends a the pump, but what's posted there is what it is. And there's not enough flow from the secondaries to keep that fuel fresh despite what you think. I've taken Holley 4 bbls apart that weren't tuned to le the seocndaries open and the filter in the inlet was plugged with sludge because they were never opened. Tuned properly means what it means. Despite what your opinion is. It's just that, an opinion.

 

Well, I never claimed that the pumps carried products different than what was posted. I never said that e10 was anything besides e10. Some pumps here have e10 that is 87 octane and straight gas that is 91 octane, thereby making a relationship at those pumps that if I want to avoid ethanol, I have to pony up for the premium fuel. Does that make sense? It is in fact a total crap shoot which ethanol blend and octane and combination thereof will be at any given pump. I'm not saying that each individual station is varying day to day, I'm saying that station to station varies even within the same company. If you are in an unfamiliar town your guess is as good as any what combination the pumps will have. Ok...I said "regular" to mean "conventional" and altogether avoided marketing terms like "premium" but the context was right there, buddy. The OP is clearly in a situation where it is e10 87 or 91 gasoline with no ethanol labeled as options.

Regarding the 4bbl tuning, and opinions aside, there is no reason that the secondary fuel flow should be so small as to let that fuel get stale.. OP quoted taking 80 mile trips DAILY with this vehicle. That's 6+ hours of run time per week minimum. Yes, there is proper tuning and improper tuning; The evidence of sludge you mention is merely anecdotal without any other information regarding that carburetor and it's use. There's an old tire guy in my hometown that won't touch Michelins "because they explode" which in reality means "I blew one up 40 years ago." It's not useful evidence regarding Michelin tire quality. That is a single data point in a pool of millions.

FWIW, some opinions are, in fact, facts. That's mind-blowing, to say the least. Thank you for your opinion regarding my opinion being an opinion. I hadn't thought of it that way and your advice was certainly eye-opening.

Please let me know specifically where my carburetor knowledge is not fact so that I can be further enlightened. Such gems as "a 4bbl carburetor does not idle on the secondaries in spite of the FACT that there is an idle port and transfer slot" are the most useful lessons in my continuing education on carburetors.

 

The stations we have here are very consistent in terms of what's available. We have E10 in 87, 89 and 93. And conventional 87 and 91. It's not a crap shoot. If you do business at the same station, you'll have the same fuel, day in day out. In traveling back and forth to Colorado from here (Louisiana) that changes to E10 in 85, 86, 88 and 91 with no conventional gas available that I've found. And that Holley where I found mud in the secondaries ? That was a nearly new carb I picked up at a local speed shop. One of those Edelbrock converts who never learned to tune a carb and never ran a fuel filter. If he had the red mud in the filter in the secondary inlet wouldn't have been there. And just it's presence proved your theory wrong about fuel flow through the secondary idle circuit being sufficient to keep the fuel there fresh. The OP's secondaries flooding also tells me the fuel there was stale and allowed the needle valve to get sludged up enough to allow it to stick open from stale fuel deposits.

 

2 stations here of the same company within a mile of my house have 2 different combinations at the pump which are also different from the other company's gas, also within a mile.

Are you seriously attributing something you found in a used carb as proof? C'mon, man...you literally just said yourself that if had used a filter, the red mud wouldn't have been in the secondary inlet, which would indicate that even you think the spoilage or contamination was occurring upstream...

The OP's flooding could be due to contaminants from multiple sources.

 

I drive the truck 75mph hr round trip every day..shouldnt the secondaries be opening at this point? RPM is not low enough not to I would assume.

 

As could it happen the way I posted. Nice try, but you've made absolutely no points here. Not sure what your problem is here, but you seem to take issue with everything I post. Did someone pee in your Wheaties again ?