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Man

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HTG y'all,

I've got a BII with the 2.8 that's giving me some trouble. It's durasparked with some older Ford two barrel carb and distributor.

Here's the situation:
Idles rough, but can hold an idle down to 6-700 rpm (set it to ~9 cause its stick). Starts right up. Doesn't smoke. Doesn't leak. Accelerates alright for what it is. Doesn't heat past ~205 when driving. There is some exhaust tick.

When I pull the plug wire for cylinder 1 (passenger-front), rpm drops to about 6-7, but idles a LOT smoother.
Pulling the wire for 2, 3 there's no change in roughness or rpm.
Cleaned distributor out, it looks ok. New plugs, and swapped wires around. So I'm confident it's either compression or fuel. Gut feeling says fuel even though logic says compression.
Idiotically, plugs got mixed up so I don't know which ones came from which cylinders. What a headache.

Now, I was thinking maybe 2, 3 are misfiring due to a hg leak between them. This would keep the fluids clean and explains why idle rpm/roughness aren't affected. But does it explain why cyl 1 is causing the engine to run rough? Could it really run ok on just 4, 5, 6?
I'm also thinking, something could be up with the intake man/valves? Maybe cyl 1 intake valve is stuck open, 2,3, stuck closed? Could the intake just be blocked somehow preventing a-f mix from getting to 2,3 so too much goes to 1?
I can't imagine timing is off with gears, engine hasn't been taken apart as far as I know. Gears can't jump unless some teeth broke but I haven't seen much about that on here.

I know I should run a comp test to know for sure about hg, but before I go to HF and pick up another gauge (my tools are mia) what am I missing? Assuming its fuel (gut never lets me down in poker), what do I do?

Full disclosure, have to sell it soon (for work), but wouldn't feel right passing it on without fixing it.
 
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Rock Auto 5% Discount Code: 7FA902352B4C01: April 5th, 2021

PanteraGT5S

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guessing no OBD - plugs, wires and coil pack(s) Fixed my `04 misfire on 4 & 6.
 

Man

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Definitely no OBDII. Not sure about OBD. if the coil was bad, wouldn't all cylinders be affected? Plugs and wires are good. D cap is fine too.
-and thank you for your service
 
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rusty ol ranger

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Its doubtful the intake is plugged unless its sat for a while and you got mice making a home in it.

Chances are very good its compression related...grab a gauge and get some readings. Carbed engines rely on vacuum (and for vacuum you need good tight seals) to suck in the fuel mix.

The only other thing you might have is a bad intake gasket. Spray some starting fluid or carb cleaner where the intake meets the head and see if the RPMs change or any other difference in idle is noticed.
 

19Walt93

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Check the valve adjustment before you check the compression or spend a bunch of money.
 

Man

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Thanks y'all.

I don't think it's a vacuum leak. Different type of rough. Vacuum is decent and fairly regular. I'll try spraying some around the intake gasket though, just tested around the carb last time. Would be an easier fix than hg. Plus, it wouldn't be exclusive to the same cylinders. No way the exhaust m is clogged up, anything in there would burn away right?

Walt, the only way to check valve adjustment is by pulling off the valve covers, huh? Just replaced the cork gaskets last year and for once there's no seep and the garage is clean. It probably needs a little valve adjustment, but could they be that out of sync to cause these misfires? The thing that gets me is, two adjacent cylinders misfiring--textbook hg between them. But on top of that, why is cyl 1 causing it to run so rough? Do you think it's two issues? Cyl 1 valves and 2,3 hg? Can't be a coincidence that all the problem cylinders are in one bank though. I guess if intake valves are off on 2, 3, then too much af goes to 1...makes sense. If intake valves are off, so are exhaust probably.
If I could bother you some more, never have adjusted valves... Is the schematic attached correct? (As in the locking nut and adjustment screw?) So I turn the nut on the rocker arm opposite to the valve, tightening it would close the valves and opening it would open the valves? I'll watch a video or something to know exactly what to do. Also does .014C for intake and .016C for exhaust refer to inch or cm? What's the C? Guess I need to get some shims.

Couldn't spend a bunch of money even if I wanted to, why I'm being so cautious here.
 

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You said you got the wires mixed up. Are you sure you got them back right? If two wires were in the wrong place, that would explain the one cylinder not working and the other one acting weird.
 
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Man

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Wires are in the right place. I mixed the old plugs up as in not sure which cylinder each came from, although from what I remember it looked like at least one was running cold (prob 2 or 3). What I did to test if the wires were good, is I just rotated the wires around and checked if the misfires followed. The same cylinders were misfiring, so I concluded the wires were not the problem.
 

19Walt93

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Thanks y'all.

I don't think it's a vacuum leak. Different type of rough. Vacuum is decent and fairly regular. I'll try spraying some around the intake gasket though, just tested around the carb last time. Would be an easier fix than hg. Plus, it wouldn't be exclusive to the same cylinders. No way the exhaust m is clogged up, anything in there would burn away right?

Walt, the only way to check valve adjustment is by pulling off the valve covers, huh? Just replaced the cork gaskets last year and for once there's no seep and the garage is clean. It probably needs a little valve adjustment, but could they be that out of sync to cause these misfires? The thing that gets me is, two adjacent cylinders misfiring--textbook hg between them. But on top of that, why is cyl 1 causing it to run so rough? Do you think it's two issues? Cyl 1 valves and 2,3 hg? Can't be a coincidence that all the problem cylinders are in one bank though. I guess if intake valves are off on 2, 3, then too much af goes to 1...makes sense. If intake valves are off, so are exhaust probably.
If I could bother you some more, never have adjusted valves... Is the schematic attached correct? (As in the locking nut and adjustment screw?) So I turn the nut on the rocker arm opposite to the valve, tightening it would close the valves and opening it would open the valves? I'll watch a video or something to know exactly what to do. Also does .014C for intake and .016C for exhaust refer to inch or cm? What's the C? Guess I need to get some shims.

Couldn't spend a bunch of money even if I wanted to, why I'm being so cautious here.
You won't need any shims, you loosen the locknut and turn the screw to adjust them. It's .014" cold and .016" cold, that's what the "C" means. If you find one really loose it could mean a worn cam lobe or valve sticking, preventing it from seating. It might be worth removing the EGR spacer and checking to see if it's corroded through underneath, allowing exhaust or air to be sucked in. A 2.8 intake is split down the center because of the firing order, a leak on one side of the carb would affect one side of the engine, unlike most engines. For example on a 302 or 351, the center 2 cylinders on one bank share an intake manifold runner with the outside cylinders on the opposite bank.
 
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Man

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Got it. If the valve is sticking, that's likely due to carbon buildup or bad guides, right? I'll check the valves and update.
EGR has been removed with duraspark, there's just a plate there and no corrosion. It's a healthy truck other than this damn roughness.
 

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Did you put the carb spacer felpro 60529 between the carb and the manifold? Carefully sesurface the carb base with 200 grit paper on a flat surface like a tablesaw using a figure 8 motion until it all shines the same. Then install the new spacer with two new gaskets I prefer making my own. Then slowly pull the carb down to just snug never overtighten a carb down. That will solve any vacuum leaks at the base of the carb sounds like part of your issue. Then preadjust the idle air needles out 3 1/2 turns out from lightly seated these little engines like a rich idle mixture then you will be able to achieve 700rpm and a smooth idle. Do you know what size the high speed jets are? Get two #42 jets and replace them with the carb out that will bring that engine to life on the open road and for pulling mountain passes. Carb spacer is very important and make sure the timing is exactly 10 dbtdc with the vac disconnected at the distributor. GL
 

kimcrwbr1

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BTW I have been running autolite single platinum plugs for going on five years with the same plugs. I keep threatening to change the plugs but the engine tells me not to. We will see if it makes it another winter...
 

rusty ol ranger

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Did you put the carb spacer felpro 60529 between the carb and the manifold? Carefully sesurface the carb base with 200 grit paper on a flat surface like a tablesaw using a figure 8 motion until it all shines the same. Then install the new spacer with two new gaskets I prefer making my own. Then slowly pull the carb down to just snug never overtighten a carb down. That will solve any vacuum leaks at the base of the carb sounds like part of your issue. Then preadjust the idle air needles out 3 1/2 turns out from lightly seated these little engines like a rich idle mixture then you will be able to achieve 700rpm and a smooth idle. Do you know what size the high speed jets are? Get two #42 jets and replace them with the carb out that will bring that engine to life on the open road and for pulling mountain passes. Carb spacer is very important and make sure the timing is exactly 10 dbtdc with the vac disconnected at the distributor. GL
3 1/2 turns????

1.5 turns is factory spec. 3.5 is way to rich.
 

kimcrwbr1

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3 1/2 turns????

1.5 turns is factory spec. 3.5 is way to rich.
Just going by my experience I get around 18mpg at between 3 to 3 1/2 turns out with #42 high speed jets...
 

19Walt93

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1 1/2 turns is the starting point, there isn't a spec measured in turns. With the engine idling warm, slowly turn one screw out until the rpms or vacuum are at their highest point, repeat on the opposite side. Recheck both screws by turning them in and out slightly to get the leanest, best idle. If you have the screws 3 1/2 turns out your jets are too small. 18 mpg is not impressive, I averaged 16mpg all summer with the 351 4 Just bolting a plate on in place of the EGR valve doesn't mean the spacer isn't corroded through. Remove the carb, remove the spacer from the manifold and inspect the underside. We used to replace a bunch of them for corrosion, it got to the point where Ford released cast iron replacements for the aluminum spacers on V8's.
 


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