Hello!

I have an 85 F-250 lariat 4x4 with 460 V8 and automatic trans that I acquired not too long ago. It has an edelbrock 750cfm 1411 carburetor (installed by previous owner) and the stock intake on it.

During cold startup, the engine hesitates when accelerating from a stop. If I am at a stop with vehicle in Drive, and I apply the gas pedal, it hesitates/lags for about a second and then engine completely stalls. Other times if I accelerate from a stop when cold, the engine hesitates for a second and then accelerates, not in a smooth and gradual manner. It does this every time until the engine fully warms up about 15 minutes after starting and then the issue disappears. When fully warm engine runs well, idle seems good and there is no hesitation when accelerating.

I am kinda a newbie when it comes to carburetors so I am not sure if this is something usual on carbureted vehicles or not. I did some research on the edelbrock 1411 carburetor and read about others having issues due to being adjusted a bit leaner than other carburetors out there. Other forum posts I read don't recommend the edelbrock carburetor at all.

Do you think this issue would disappear with a different carburetor? I was thinking of changing in the future with a Holley 4160 and an aluminum intake manifold. Do any of you recommend going this route?

 

I have the same truck, although I have a manual transmission. And my 460 with a 1411 Eddy starts and runs extremely well, cold or hot. My guess is that you have the choke adjusted too lean.

The adjustment procedure is shown on Page 8 here: http://www.edelbrock.com/automotive/...ers-manual.pdf. However, I suggest you do it an easier way. There are three screws holding the black cap of the choke to the carb. Loosen them slightly to allow turning the cap - but note or mark the position of the cap before turning it. Then hold the throttle open slightly and turn the cap counterclockwise one notch. (I think it is CCW.). That should close the choke plate more than it was, assuming the engine is cold, and give you a richer mix for startup. And if one notch isn't enough turn it one more.

And I don't recommend a Holley. I like the simplicity of an Edelbrock, and I find them to be more reliable than a Holley.

 

Thank you so kindly for the reply and for explaining how to adjust the choke! I will try that out, I am sure it will solve the hesitation.

I am glad to hear that your truck runs well with the Eddy carburetor, I read those other forum posts and kinda got discouraged so I am happy to hear you have good results with this setup.

 

I like the Holley myself.

What your experiencing is the reason they went to fuel injection. Carbs were always a compromise, with lots of different crutches to overcome problems. The largest problem is the intake manifold, it's called a "wet manifold" since fuel and air are sent to the different cylinders through it.

The problem is the engine will not burn liquid fuel, it has to be atomized into a fine mist. The carb works somewhat like a spray gun works, air going through it picks up the fuel and sprays it into the intake. This is where the problems begin, when the mist of fuel hits the cold intake, it turns back into a liquid. The liquid rolls around in the bottom of the intake, some cylinders get a gulp of the liquid fuel and are too rich, others don't get any fuel at all just air, so they don't fire. That's why the engine runs so rough and stalls.

1st thing to check like Gary said is the choke. The choke blocks the air going into the carb, making the carb run richer (more fuel). Overwhelming the engine with a richer mixture at least gives some cylinders more of a chance to get some fuel of some sort, even if it's liquidfied.

2nd, the choke is tied into the throttle. As the choke is activated, your idle speed should be higher. This higher engine speed increases the air speed going through the carb and into the intake. This helps keep the air/fuel stirred up and distributed better through the intake. The more choke, the higher the engine speed.

3rd, Heat. It's important to get heat into the intake system. What you are doing now is waiting for the heat from the engine to make it's way up into the intake. This can take a long time. What the factory did was make a exhaust port in the center of each head, so exhaust will pass through underneath the carb to help warm the intake up very quick. The factory also had a large aircleaner with a pipe that led down to the exhaust manifold with a temp sensor, and this drew warm air up from around the exhaust manifold into the carb. Warmer air will hold more fuel in suspension. All this heat stuff is subject to previous owners reading hot rod magazines and they tell them more heat means less power. On the track this is true, but on the street this heat is needed during cold weather to make the engine driveable.

Fuel injection doesn't have these problems so much, they do not have fuel in their intakes, only air. They spray the fuel into the cylinder head right behind the intake valve where it has a better chance to fuel the cylinder properly.

 

I have an Eddy on both Big Blue, which has the 460, and Rusty which has a 351M. Rusty's is a 1406 Performer that is a 600 CFM unit.

Both of these carbs are tuned 2% leaner than Edelbrock's performance carbs in an effort to provide better economy. But, by being lean they require a bit more choke when cold than a carb tuned for performance, so it isn't surprising that you have to take some time to adjust the choke. However, once you've done that you should enjoy the carb for a long time.

That's one of the many things I like about Edelbrocks. In contrast, the Holleys I've had came out of the box jetted too rich. While that meant the choke adjustment wasn't critical, it also meant they got poor fuel mileage. On the other hand, a Holley seems to have an edge in all-out acceleration. So, if I were going racing I might chose a Holley. But for everyday driving I'll take the Eddy.

 

Dave has a good point that I forgot to mention - the air cleaner. This page on my web site explains how the factory air cleaner works: Air Cleaners - ???Gary's Garagemahal. As Dave points out, carbs need heat and ditching the factory air cleaner for an open-element unit defeats one of the systems the factory engineers designed in to provide heat.

Having said that, Big Blue has an open-element air cleaner and still runs extremely well in fairly cold weather. I'd rather have a factory unit on it, but he came with an open unit when I acquired him and it has worked fine so far.

 

Thank you both for explaining the carburetors to me and the role of the factory air cleaner, that helps clear things up for me. My carburetor also has an open element air cleaner but I think I have the factory one in a box with spare parts that came with the truck.

So for the choke adjustment, I just step on the throttle first to set the choke and then loosen up the three screws on the black cap and turn it to make it slightly richer?

 

When starting the truck yes step on the throttle to set the choke.
But when adjusting I would hold it open, this way you can see if you are going in the right direction when you turn the cap.


If you go the wrong way you will see it open more.
Now that I think of it the cap maybe marked <lean - rich> ? or the other way around.
Dave ----

 

I was wrong about which way to rotate the cap. So, I wrote it up on my web site: Edelbrock - ???Gary's Garagemahal

 

Yes, hold the throttle open while you turn the black thing(engine off of course). As the choke activates like I mentioned before, it increases the idle speed by moving a fast idle cam on a throttle stop. If you do not open the throttle all the way the fast idle mechanism can interfere with your adjustment of the choke door.

Try not to push the throttle open too many times, if you do you will probably flood the engine. No problem really, but that will explain why it's a little stubborn to start after you have messed with it.

 

Thank you all for the replies, I have an update:

I adjusted the choke, initially it was set to one notch above the midpoint (lean) and I adjusted it 3 notches rich. I set the choke, started the truck and let it warm up 2 minutes, the put in drive and it ran perfect and this morning it was 20 degrees outside here in Michigan. No hesitation or stalling whatsoever all while warming up, the adjustment did the trick!

Thank you again Gary and Franklin for suggesting to adjust the choke and explaining to me how to do so, just like you said Gary, the choke was opening too soon and caused it to run lean while warming up.

Very happy with how its running, I appreciate the help!

 

Excellent! I find that a notch makes a pretty big difference, so you may find that 3 notches rich is too much. However, about all that "too much" hurts is the MPG, so it may not be a problem. But, electric chokes tend to come back on earlier than other chokes as the engine is cooling down, and too much choke on a warm engine can cause hard starting. So, watch it and see if you need to back off a notch or two.

And, enjoy! That 460 should run well now. Mine sure does!

 

Good job, Chief!

You are getting really close, but you should not have to "let it [engine] warm up 2 minutes." If everything else is in place and set correctly, only 20 seconds or so should be all that is needed - even in temperatures as low as 20 degrees.

Once the engine fires, let it idle for about 10 - 15 seconds or so. The idle speed should be around 1500 - 1750 RPM. Then lightly press the gas again to drop the fast idle cam down a notch. The idle speed should then be around 1000 RPM. (In really cold conditions, the idle may not drop down at all. If so, let it idle 10 more seconds, and try again.) The idle will still a bit higher than normal, but low enough for you to be able to drive away without any problems such as hesitation, stalling, etc. As the engine warms up from driving (which is the quickest way to warm the engine up), the idle speed will gradually come back down to normal. That is how a properly set up choke system *should* work.

You will find that a properly set up and tuned carburetor can run just as good as any modern fuel injected vehicle. But to make that happen, you absolutely must have a working choke system and a source of heat to the carburetor.

I bet that if you replaced the racing-style open element air cleaner for the stock thermostatic air cleaner and hook everything up correctly, your truck will run even better.