1985 2.8 Carb Adjustments

[RonD]

Just as a heads up starting cold, the battery/system voltage
Cold temps bring out battery issues, in the form of low voltage to the coil/spark system when cranking the engine
Usually voltage will stay above 10volts while cranking
If it drops below 9.5volts you will have a very weak spark

 

[ford4wd08]

Just as a heads up starting cold, the battery/system voltage
Cold temps bring out battery issues, in the form of low voltage to the coil/spark system when cranking the engine
Usually voltage will stay above 10volts while cranking
If it drops below 9.5volts you will have a very weak spark

Thanks for the tip, the coil is new this year as well as the TFI, plugs, distributor cap, rotor, and wires. The battery is less than a year old as well. Hopefully I don't have any ignition issues!

I will throw the battery charger on it when I get home though so I can confirm it is hot. I checked the other day when looking for the wire to hook the choke to on the alternator and the battery voltage was 12.7 or 12.8 without it running.

Once I get it starting correctly, I am going to change it to Motorcraft plugs, I have some Autolites I put in there because that is I could source locally, but I have 6 new Motorcrafts to put in as well.

I have probably fouled the plugs that are in it now by running it too rich a time or two.

 

[RonD]

I would still test battery voltage while cranking, pull coil distributor wire, so No Start, and just see what it drops to
Cables or starter motor can drop voltage too far

2.8l is a lower compression engine, 8.7:1
Spec'ed spark plug gap is 0.044, I would try 0.046

 

[ford4wd08]

@RonD @Uncle Gump

With both of your help, I think I've got it figured out!

I didn't have the fast idle at the V on the cam. It was way past it, so literally choking the motor out the entire time.

I only have one step as I suspected, but seems to running well. I attached a picture of it. This is before I adjusted it correctly.

Here is a video of it just after it started on a cold start.

And here is another one after it warmed up for a while.

How does it sound? I think I have the carb tuned in pretty well now?

Gump, your walk through helped. I really appreciate it.

Ron, your knowledge is always appreciated as well.

 

[Uncle Gump]

I would say I'd probably turn the fast idle speed screw another half turn. Didn't sound like there was much of a difference between idle and fast idle.

Another lesson at Uncle Gumps carb class if you care to read...

Engine fully warmed and idling... fuel mixture screws (the ones at the base of the carb). Slowly turn either the left or right in by 1/4 turns. Turn inward until the engine starts to miss. Now turn outward 1/4 turn until you get the smoothest idle and fastest RPM. Repeat on the other screw.

Overall I think it sounded pretty good... glad to help. Funny thing... I probably haven't adjusted a choke in 25 years or more. I guess it's like riding a bike....

 

[ford4wd08]

I would say I'd probably turn the fast idle speed screw another half turn. Didn't sound like there was much of a difference between idle and fast idle.

Another lesson at Uncle Gumps carb class if you care to read...

Engine fully warmed and idling... fuel mixture screws (the ones at the base of the carb). Slowly turn either the left or right in by 1/4 turns. Turn inward until the engine starts to miss. Now turn outward 1/4 turn until you get the smoothest idle and fastest RPM. Repeat on the other screw.

Overall I think it sounded pretty good... glad to help. Funny thing... I probably haven't adjusted a choke in 25 years or more. I guess it's like riding a bike....

Half a turn tighter for fast idle? Does not having two steps on the cam effect fast idle and idle?

I adjusted the fuel mixture screws tonight as well. On a warm engine I adjusted them in until it began to miss, then back out to smooth idle. About a quarter of a turn.

 

[Uncle Gump]

You probably have the mixture screws where they need to be per your adjustments you stated.

There should be two screws that control speed of the engine. Idle speed screw and a fast idle speed screw. One shouldn't affect the other... unless they're way out of adjustment. The idle speed screw contacts the throttle shaft. That one sounded pretty good to me. The fast idle speed screw... item 4... I would try another 1/2 turn tighter (faster). Turning the fast idle speed screw should have zero effect on base idle.

 

[ford4wd08]

You probably have the mixture screws where they need to be per your adjustments you stated.

There should be two screws that control speed of the engine. Idle speed screw and a fast idle speed screw. One shouldn't affect the other... unless they're way out of adjustment. The idle speed screw contacts the throttle shaft. That one sounded pretty good to me. The fast idle speed screw... item 4... I would try another 1/2 turn tighter (faster). Turning the fast idle speed screw should have zero effect on base idle.

The idle speed screw and fast idle speed screw are on opposite ends of the carb from each other right? Idle speed is over on accelerator pump side (in this case) and the fast idle is over on the choke side.

 

[Uncle Gump]

That is correct...

 

[ford4wd08]

That's what I thought, just wanted to confirm.

I haven't touched the idle adjustment even during the carb rebuild.

I'll tighten the fast idle screw in another half turn tonight and see what we get.

Just waiting to hear back on my driveshaft from the shop, and I'll have this puppy on the road!

 

[19Walt93]

The "V" you have on the fast idle cam is the second step, that's where the fast idle screw should sit when the choke pull down has vacuum and you tap the throttle to make it drop down. Before the pulldown has vacuum the screw should be on the top step holding the throttle open more. Most 2.8's, even back in the 70's in Pintos and Mustangs would flood if you pumped the throttle more than once cold, you don't even need to floor the throttle as long as you open it enough for the choke to close. With the engine warm and the fast idle on the second step the engine should be running around 1500. I would also warm the engine and set the idle mixture screws before doing any other adjustments. Using a tach or a vacuum gauge slowly turn one screw looser until the idle starts to lose speed or vacuum, then tighten the screw until it starts dropping again, then loosen the screw a whisker. Do the other side then go back and recheck the first one. No, whisker isn't a Ford term ,we used to say c**t hair but I've gotten smoother as I've aged.

 

[ford4wd08]

The "V" you have on the fast idle cam is the second step, that's where the fast idle screw should sit when the choke pull down has vacuum and you tap the throttle to make it drop down. Before the pulldown has vacuum the screw should be on the top step holding the throttle open more. Most 2.8's, even back in the 70's in Pintos and Mustangs would flood if you pumped the throttle more than once cold, you don't even need to floor the throttle as long as you open it enough for the choke to close. With the engine warm and the fast idle on the second step the engine should be running around 1500. I would also warm the engine and set the idle mixture screws before doing any other adjustments. Using a tach or a vacuum gauge slowly turn one screw looser until the idle starts to lose speed or vacuum, then tighten the screw until it starts dropping again, then loosen the screw a whisker. Do the other side then go back and recheck the first one. No, whisker isn't a Ford term ,we used to say c**t hair but I've gotten smoother as I've aged.

Thanks for that, that makes sense.

Especially the c**t hair! lol I work in a factory and the guys around there know how to weave their words into quite the story....

 

[ford4wd08]

Went out tonight and adjusted the fast idle screw half a turn.

Pressed the accelerator and she fired right up!

Noticed the fast idle was higher (as it should have been) and the engine warmed up a lot quicker.

Came off fast idle and sounded great.

It hasn't ran this well in 10 years. So happy I got it running well.

I appreciate all y'alls help. @RonD @Uncle Gump @19Walt93

I have some rattling (marble in a tin can sound). The original catalytic converter might be on it's way out. I think it may need a new exhaust to begin with. I'll get it squared away and when the driveshaft gets in I'll be driving it everyday.

I did start the insurance on it again today, so I'm close!

 

[19Walt93]

If your cat is breaking up fix it before you put the new exhaust behind it, I can't count the mufflers I've seen plugged with pieces of cat substrate.

 

[kimcrwbr1]

Do not replace the cat if you have old valve guide seals. Oil in the exhaust will quickly destroy the new cat. You can replace the seals without pulling the heads. I am on my third year with autolite single platinum plugs cold starts like a dream. Slap the muffler with the palm of your hand if full of crap just rod out the cat and install a new muffle. The cat must be there but it aint gotta do anything...