Engine juddery, loss of horsepower.

[None_zero]

Ok I have one more question about the valve lashing thing. Because when I start it this morning it's making even more noise from the valves. Set tdc cylinder 1, check. Turn one rotation till 4th cylinder is at the top.... this means I put the socket on the crank with the handle pointing left and rotate clockwise until its pointing right reposition to pointing left and repeat. Now I've turned the crank 360° and I should be in the correct position. Are the valves all closed in this position?

[None_zero]

Ok update: valves set properly... finally (third times a charm) choke adjusted back to position a little off center towards the passenger side. Intial result, performance dramatically increased. Hard to say exactly on gas consumption due to having to take a crazy detour on the way in today but it's looking like I'm getting a lot more fuel efficiency. I added some seafoam to the gas and poured a little in the crank case and carb to try and remove some of the excessive carbon build up. And ran blue devil through the coolant system, I'm about to go drain it and flush shortly. But it seems like everything is looking up. I'll try to update once the additives are out about how it's doing . I suspect I may need some fine tuning to the air fuel mix and such but maybe I just got lucky and nailed it. Because it felt great on the way in today

[datzenmike]

So third time... is the choke open once the engine warmed up ????? This is important for good mileage as the choke forces a rich mixture for cold starting and warm up, but once warm if it's still on even partly it will seriously affect MPG.

 

I never use any additives. The engine is self cleaning without it if the choke is off and you drive it far enough. See above statement.

 

You cannot adjust the air fuel mixture for driving without taking the carburetor apart. You CAN adjust the mixture for idling though. Note here that the '84 carburetor is set at the factory and the idle mixture screw sealed with an aluminum plug. Have you removed this plug?????

 

 

 

[None_zero]

I think I already answered this but yes the choke is open when warm now as to that small aluminum plug... don't laugh. I've not removed that plug, so if it's still in there I've been screwing it in and out wondering why it's so hard to tell when you've got it right. And I'm pretty sure it's still in there because that is what mine looks like 

Edited February 15, 2023 by None_zero

[None_zero]

Initially when I was attempting to adjust the air fuel mix which started long ago and ended with me thinking loss of compression in the cylinders was the reason for why all my attempts to adjust it end up having little effect. I started off messing with it because all the carbon build up suggests I'm running really rich. And inwas trying to solve that so I wouldn't change the oil and have it be black the next day. Or get poor performance from sparkplugs that are caked with carbon. So what should I do as a first step to fix that? If my choke is operational and full open when at operating temp. What is the next thing I look for? Also I had/have issues with what I'd describe as over idle. Where if I stop and keep the clutch depressed the rpms will spike and make the engine race it varies how much it does it but it goes up as high as 2000 rpms while sitting stopped which makes me feel like the engines going to blow up when I'm getting 2k rpms with no gas pedal being pressed I assumed this was because the choke was sticking open or something but I'm coming to realize how very little I actually know about that. This effect of over revving is greatly increased if I. Braking and turning left. I have no idea why.

Edited February 15, 2023 by None_zero

[datzenmike]

The picture was with the plug removed, I wasn't clear on that.

 

Guess I didn't see the reply on the choke being open, sorry.

 

What about the clicking sound turning the ignition on off on off on??? If thst's not working the idle mixture won't be adjustable either.

[None_zero]

4 hours ago, datzenmike said:

The picture was with the plug removed, I wasn't clear on that.

 

Guess I didn't see the reply on the choke being open, sorry.

 

What about the clicking sound turning the ignition on off on off on??? If thst's not working the idle mixture won't be adjustable either.

I'll try this momentarily. I'm 90% sure it works but I'll check and be sure, ok just checked and yes it does click when in the on position 

[datzenmike]

Good the idle and mixture for idle can be adjusted...

 

 

Lower the idle if possible using the idle speed screw. This makes any mixture adjustments easier to notice.

Turn the mixture screw in (leaner) or out (richer) and try to look for the fastest strongest idle. There may be 1/2 a turn where the idle is good but not any change, just set in the middle. Idle will have gone up so turn it down with the speed screw and repeat the back and forth mixture adjustment to find the strongest fastest idle. Do as many times as needed until you can't make it any better and the idle speed is 700-800 RPMs. 

[None_zero]

7 minutes ago, datzenmike said:

Good the idle and mixture for idle can be adjusted...

 

 

Lower the idle if possible using the idle speed screw. This makes any mixture adjustments easier to notice.

Turn the mixture screw in (leaner) or out (richer) and try to look for the fastest strongest idle. There may be 1/2 a turn where the idle is good but not any change, just set in the middle. Idle will have gone up so turn it down with the speed screw and repeat the back and forth mixture adjustment to find the strongest fastest idle. Do as many times as needed until you can't make it any better and the idle speed is 700-800 RPMs. 

Ok this process I have done many times but maybe other factors were in play also. Since we've rules out several factors perhaps I'll finally get it right. It was interesting to learn that idle airfuel mix and driving air fuel mix is completely separate. I have no doubt messed with the mix before trying to fix an issue while it's running. It's likely that I've created all sorts of inconsistent conditions trying to correct another aspect of how it was running and was just barking up the wrong tree. I'm working late today but will update once I've got the mix corrected 

[datzenmike]

Idle is  about 700-800 RPMs and above this it transitions to running on the primary barrel but it's maxed out by 1,000- 1,200 RPM. The mixture produced by the primary is set by the primary jet and that is fixed and inside the carburetor. Generally the primary jet is around 105 plus or minus. My L20B was a 99 but this was because it was from Nevada with an average elevation of 5,500 ft. Thinner air needs less gas and smaller jet. I have a local L20B carburetor and it had a 112 jet because I am literally at sea level. So I put that in and performance was noticeably better and gas mileage improved also. The jet size isn't that important as they will all work but if you had a wide band O₂ gauge you could split hairs and change the primary jet to get a closer to perfect mixture.

[DwayneOxford]

12 hours ago, None_zero said:

Top vacuum hose? Can you be more specific. Are you talking about the one that runs out along the Intake on the air cleaner to the vacuum valve positioned at the opening?

The one in your pictures.

[DwayneOxford]

None_zero did you work at Trader Joes?

[None_zero]

On 2/15/2023 at 6:30 PM, DwayneOxford said:

None_zero did you work at Trader Joes?

No why?

[DwayneOxford]

2 minutes ago, None_zero said:

No why?

Met a young man who did a few years back, just thought you might be him.

[None_zero]

On 2/15/2023 at 4:28 PM, datzenmike said:

Good the idle and mixture for idle can be adjusted...

 

 

Lower the idle if possible using the idle speed screw. This makes any mixture adjustments easier to notice.

Turn the mixture screw in (leaner) or out (richer) and try to look for the fastest strongest idle. There may be 1/2 a turn where the idle is good but not any change, just set in the middle. Idle will have gone up so turn it down with the speed screw and repeat the back and forth mixture adjustment to find the strongest fastest idle. Do as many times as needed until you can't make it any better and the idle speed is 700-800 RPMs. 

Ok I waited to do this for my new airfilter to come in. The old one was black as midnight from the blowback of exhaust from the air cleaner intake that occurs when I shut the engine off 3 out of 5 times I figure a clean filter will get me the best result setting idle. However I followed the steps as outlined and lowered the rpms by turning the idle set screw out. Then I turned the idle air fuel mix in about half turn at a time until it was as lean as it would go with no consistent noticeable change. So I went the other way and turned it out until I thought I noticed a change but as I worked it back and forth (pausing after each adjustment) It seemed like there was no change or only a very slight change that was hard to find the sweetspot in the middle of. In the end I turned it all the way in and then back out 2.5 - 3 turns which is within the range of what seems the highest rpm then turned the set screw back in to get back to around 700-800 rpms. It doesn't seem right though. All the demonstrations I've watched of this in videos and the way you describe a change significant enough to raise the rpms after you lowered them. I'm not getting anywhere near that much change from the adjustment --  maybe this has nothing to do with it but I've got oil on the back of the block some of it old and some looks pretty fresh or is on areas I've cleaned to see if new oil would appear so I'd know if I was leaking. Trouble is I can't find where it's coming from I checked all around the valve cover gasket as I've been in and out of there last few days and it seems fine possibly a little bit from where a ground was added on a valve cover screw but not enough to account for what's there. And also a bit from the oil cap itself which seems like it's running down the length of the valve cover on top of where the gasket is so maybe it's riding that flat surface back to the back of the block.. is there supposed to be a rubber seal between the cap and the crankcase? And could a loss of air pressure in the crankcase cause the idle to rise as I'm driving it? I noticed yesterday before I made any adjustments that my idle was slowly creeping up so that instead of 1000 rpms at full stop with clutch depressed it was 1200-1400 and when clutch depressed and braking (not quite stopped) it spikes to 2000-2200. I'll add one more thing. It seems like the truck uses a lot of gas at idle like the needle moved noticeably just from me warming it up and making my adjustments which all together probably took 45 minutes at the absolute most 

Edited February 18, 2023 by None_zero

[None_zero]

9 minutes ago, DwayneOxford said:

Met a young man who did a few years back, just thought you might be him.

Lol was he a dumb ass? I'm kidding but not at the same time.

[datzenmike]

If you turned it all the way in and it kept running then something is wrong. Am I understanding you properly?

 

You said your idle is at 1,000 RPMs??? it should be at about 700.

 

 

[None_zero]

11 minutes ago, datzenmike said:

If you turned it all the way in and it kept running then something is wrong. Am I understanding you properly?

 

You said your idle is at 1,000 RPMs??? it should be at about 700.

 

 

Before I made the adjustment it ran at about 700-800 until I depress the clutch. Then it jumps up to 1k so if I stop and leave it in gear and keep the clutch depressed it sits at 1k but if I take it out of gear and release the clutch then it drops back to the normal level. But it was slowly creeping higher and higher each time I'd drive it 

Edited February 18, 2023 by None_zero

[None_zero]

If I back the mixture screw all the way out to check for something blocking it, (like maybe when it feels bottomed out it isnt) are any springs or anything going to fall out?

[datzenmike]

Didn't answer. Did it keep running when mixture screw was all the way in?

[None_zero]

45 minutes ago, datzenmike said:

Didn't answer. Did it keep running when mixture screw was all the way in?

Yes. That's why I'm saying maybe it feels like it's bottoming out but isn't actually bottoming out. Can I remove it and look or are things going to come out that shouldn't once it's out (it meaning the mixture screw) to be more precise when I turned the mixture screw in until it stopped their was little or no change to the way it was idling. Which obviously seemed wrong to me, since I assumed that turning it all the way in would close it but I wasn't sure if it had a minimum opening that was maintained even at lowest setting 

Edited February 18, 2023 by None_zero

[DwayneOxford]

2 hours ago, None_zero said:

Lol was he a dumb ass? I'm kidding but not at the same time.

Nah, good kid, liked his 720.

[datzenmike]

2 hours ago, None_zero said:

Yes. That's why I'm saying maybe it feels like it's bottoming out but isn't actually bottoming out. Can I remove it and look or are things going to come out that shouldn't once it's out (it meaning the mixture screw) to be more precise when I turned the mixture screw in until it stopped their was little or no change to the way it was idling. Which obviously seemed wrong to me, since I assumed that turning it all the way in would close it but I wasn't sure if it had a minimum opening that was maintained even at lowest setting 

 

Turning the mixture screw all the way in shuts off idle fuel the engine should quit.

 

Find this on the engine side of the carburetor...

 

 

Take the rubber plug out of the center and turn the screw inside counter clockwise one or two turns, keep track so you can put it back later if this does not help.

[None_zero]

On 2/18/2023 at 4:15 PM, datzenmike said:

 

Turning the mixture screw all the way in shuts off idle fuel the engine should quit.

 

Find this on the engine side of the carburetor...

 

 

Take the rubber plug out of the center and turn the screw inside counter clockwise one or two turns, keep track so you can put it back later if this does not help.

Ok will do. Thanks I'll report back about the results.    --- I didn't get around to doing this yet, since my simple brake job turned into rotors, I've never had to remove a hub before to get the rotor off. I feel like I'm learning though. The state those hub bolts were in, me from a year or two ago would have snapped at least two of them trying to get that apart. This time as soon as saw it, I went and got a wire brush and some penetrating lube, a torch a mallet and breaker bar. And got them good and ready before I ever tried the first bit of torque to remove them. They all came out cleanly, although even then I had to use a chisel and mallet to separate the hub from the rotor. I even did like you said and got a new cotter pin even though I didn't have one and lazy me wanted to slide a finishing nail in there and bend the end. But you stressed the importance and I thought, what good is wise advice if you ignore it dumbass. So I got the pin 

Edited February 20, 2023 by None_zero

[None_zero]

Another update. After adjusting the idle mix the other day and getting the result mentioned above. I haven't messed with it again (busy doing brakes and such) and today the idle speed dropped to around 500 rpms with clutch engaged and bouncing around zero with it disengaged. Gas mileage through the floor. Left home today with the gauge reading 3/4 I believe and after 17 miles to work, 1/2 mile at lunch and 17 miles home (+ a bit of idling in traffic) it was touching E.... the only thing I did that I can even imagine effecting this is I topped off the oil last night before heading in. Truck was at a bit of an incline so maybe the reading wasn't accurate. But I rechecked it in the parking lot at work which is completely flat and it was right at the top line marked H which is a bit higher than I normally keep it but I think still within the acceptable range... thoughts? Also I forgot to mention the belt is squealing when i start it. It hasn't done that in a long time.

Edited February 20, 2023 by None_zero