Hey guys.

So, i've got a 1985 F-150 with a 4.9L, Inline 6 engine and a single barrel carb.


Lately, I've noticed the engine is being a bit sluggish. Not as much power is coming from the engine as it use to. It's really taking it's time to get up to speed.


What could I do to get a little more power?


Also: How many miles do YOU guys think it should be until I change the spark plugs, rotor, caps, and wires?


Alright guys, thanks for the info!

 

I noticed a huge difference when i put my breather on, but if you want to keep it stock, thats not really a good option. A generic tune up might be a good option. Exhaust upgrades can help you also.

But if you aren't worried about keeping it stock, i would go with a breather, it is cheap and easy to do yourself.

 

When's the last time they were changed?

Pull a plug and take a look. Pull the cap and look at the components underneath. If they show signs of wear, change them.

 

According to the manual... My additions are in (---).

Check clean and regap spark plugs every 6,000 miles. Replace every 30,000.

Everytime the plugs are cleaned, or replaced, Inspect and/or change the distributor rotor if it looks burned or the center electrode is grooved. Inspect and clean the electrodes on the distributor cap if needed. Replace the cap if pitted, cracked or the center electrode is worn down excessively. Check and test the plug wires resistance, replace if below specs, or if cracked or other problems exist. (book is assuming you are using motorcraft parts. Most cheaper aftermarket caps cannot be cleaned.)

Change oil every 3,000 miles, replace filter every 6,000.

Change air filter every 15,000 (recomended for Dusty conditions) 30,000 (normal)

Change fuel filter (Motorcraft FG-44-B) when needed or every 10,000 miles. (I recommend 5,000 miles with todays gas)

Change O2 sensor every 30,000. (If computer equipped.. Everyone forgets this one)

Change Crankcase breather filter every 30,000. (or sooner when dirty)

Do a computer diagnostic if equipped.

(Your carb may also be in need of a rebuild by now. Todays gasoline has a lot of ethanol added to it and that tends to break loose varnish and can plug things up. The ethanol can also eat away at older seals in the carbs. Your carb may also be vibrating loose on the four bottom screws that hold the top of the carb together with the throttle body. A little bit of BLUE locktite on the threads will prevent that in future. DO NOT use the RED Locktite as RED is for permanant assymbly.)

Hope this helps...

 

Since your truck is an 85, I am guessing it has (or had) the feedback system. If that is still in place, any one of a number of minor things can cause it to go into the "limp" mode. This locks the timing at 10* BTDC (base setting), which can really impair the power output. The computer, even as basic as it is, reads multiple sensors to determine the best AFR and timing for the current conditions. When it can't get all the info it needs, it can't operate, so it goes into the limp mode.
Today's ethanol blended fuel really causes issues with the early EFI and computer carb systems. The rather primative O2 sensor reads a false lean condition, due to the extra O2 found in the ethanol, and enriches the mixture to compensate. Unfortunately, this then causes the engine to run rich, and waste extra fuel. As an example, my 1990 Nissan gets ~15% less MPG with 10% ethanol fuel. I've checked it numerous times......

 

Tell me...

What is a breather, exactly?
Where does it go?

 

How do I fix it, exactly?

 

Does it still have the feedback system? Rather important to know, since diagnostic proceedures are totally different.

 

How many miles are on it?
When did you last do a through tune up?
Compression?
Are your cam timing gears worn?

There are plenty of parts like intake and exhaust manifolds, carbs and DSII ignition systems that swap right on and can help immensely.

 

I just hit 227,000 miles yesterday.

The last time I did a tune up was 223,000 miles. Spark plugs, wires, air filter, new cap, cleaned of the rotor. I did not change the oil or filter... I am going to do that soon, though.

Compression???

Cam timing gears worn down???

If you mean I couldn't see the timing marks, then yes.

 

How do I find out if it has a feedback system or not?

 

Fuel filter: Is it that brass thing attached to the carb that has what I believe to be the fuel line running into it?

O2 sensor... That's that one thing plugging into the oil.. something, right?

Crankcase breather filter? What is that? Where is that?

 

i call it a breather but really it is an air cleaner, it sits on top of the carb and filters the air going into the motor.


i dont know much about the carb 300, but it goes right on on 302-460 so i think it would work but i dont know.

 

Not to hijack the thread but, how do you do that? I am planning on switching over to DSII but haven't yet and mind is running like crap.

 

What 81-F-150-Explorer is referring to is the crankcase breather element, this system
allows filtered air into the crankcase to replace the fumes & blowby that are sucked out via
the PCV valve, the element is basically just a small air filter that is located inside of the
stock air cleaner housing and looks similar to this:



Installed, it looks like this:


The round, thumb-sized portion goes through the side of the air cleaner; on the other side is
a rubber hose that connects to it, other end of that hose should be stuck into the top of the
valve cover.

Paul - about your engine-running problems, go re-read 81-F-150-Explorers suggestion
again, the part at the very end about the carb possibly vibrating loose; I've read a fair bit
on here about those 6-banger carbs loosening up like that, I think there are 4 screws
accessible from the bottom side that loosen up and cause a vacuum leak.

Use the Advanced Search and search this forum's archives, I seem to remember some
good info about this having been presented in the past.

Can you post close-up pictures of your carburetor & distributor?