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High speed miss -UPDATE- we have a winner.

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Heviduty View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heviduty Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan. 2022 at 12:58pm
Lee;
 I agree Lee it sounds like a spring. That was one of the reasons I went into the valves earlier. I really checked them over because I suspected a spring might be causing my rough running issues. What I found were just very tight valve lifter clearances.     Got that adjusted and she runs perfect….. until it doesn’t.  
    I’m going to say the valve springs were checked , rechecked the next day and not found wanting.  
    They might be weak but they are not broken.    
    Thanks.   
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Steelyard Blues View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelyard Blues Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan. 2022 at 6:24pm
What carb and fuel filters do you have?

Also, what type of line are your running between the carb and pump? 

Micah
1947 CJ2A, Body & Frame: 106327, Engine: J109205, Tub and Tailgate: 97077. Originally Luzon Red

1965 Johnson Furnace Company M416 #6-1577
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heviduty Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan. 2022 at 7:59pm
Steelyard ; 
  I’m thinking that this Jeep went out of service as a daily driver due to what would appear to be fuel issues.  
  I make this determination because of the actions of the previous owner.      It has a new steel fuel tank , in-line fuel filter , new electric pump mounted within a foot and below the tank and a new repop carter carb.  All this is plumbed with new fuel hose. I am running a fuel pressure gauge on hose into the cab so I can monitor at speed.   It now holds solid between 3 and four pounds and pumps more than adequate  volume.     
   The carb was so far out of adjustment that one wonders if the previous owner might have made his mechanic mad at some point.      I ordered the carter tools and made the needed adjustments.  
   Float level , idle mix screw, accelerator pump stroke and high speed needle.      It starts and idles perfect. No flat spots on acceleration either slow or fast.   If I never tried to run faster than fifty you would say it runs perfect. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelyard Blues Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan. 2022 at 9:40pm
So, I was obviously thinking it was a fuel starvation issue. It appears as though you have this covered. In this area, I would check one last thing. Is it possible that you have a lose connection in the wiring to the fuel pump or undersized wire that, when asked upon to run full power, she is not able to draw enough voltage? 

A while back, I had a miss that drove me nuts. I could not figure it out. I traced it down to a new distributor cap. It used aluminum electrodes, I replaced it with a better cap using brass electrodes and it went away. Also, is your cap correct for the model distributor? Sometimes they get swapped out. 

Well, that's all I got.

Micah 
1947 CJ2A, Body & Frame: 106327, Engine: J109205, Tub and Tailgate: 97077. Originally Luzon Red

1965 Johnson Furnace Company M416 #6-1577
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heviduty Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan. 2022 at 11:29pm
Steel; 
 I have a temporary Fuel pressure gauge connected at the carb inlet and  mounted in the cab so I can monitor pressure at speed. Pressure never drops below 3.5 pounds ever. I am sure the issue is not a starvation in supply into the carb.    For a while I did have an issue , that’s why the I installed the gauge.  The carb seems to be doing it’s job as well as I can tell. 
  Early when I was convinced I had a fuel issue I tried grabbing a handful of choke during the stumbling period.    My thought was that if there was fuel available in the bowl it would cause an over rich situating and perhaps smooth out indicating a carb problem.  Pulled the choke and nothing changed.    I thought I was onto something.    Next test was to confirm that the test was a valid test.   I tried to prove this by pulling the choke when the engine was running good at high speed.     Nothing happened, no over rich ,  no stumble,  Nothing.     Invalid test.    
    I’m thinking that the high air velocity sucks the spring loaded plate open even though the cable is pulled. 
  The cap that came with the Jeep had aluminum contacts. I never like the use of aluminum for electrical connections or devices subject to corrosion.     I replaced it with one having brass contacts.  I have no idea if it is the correct one.   It was more of a matching up the existing cap with a new one.   
     When you tell the kid behind the counter that the vehicle is a 1943 GPW he then asks what the heck that is.     Well , it’s a Jeep built by Ford for the war department during your grandaddy’s war. 
    The eyes glaze over and out come the old books.     
  I’ve not had much luck.      It’s an IGC 4705  built mid 1943. 
      I should offer it in trade to the GPW guys in trade for a more common one

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Post Options Post Options   Thanks (0) Thanks(0)   Quote drm101 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2022 at 7:52am
I think you're just lean at cruise since you said you can step on the gas and the misfire goes away. I would adjust the metering rod up a smidge and see if that helps. Weak valve springs would float, whether wot or not, at high rpm. If you're adding throttle and the miss goes away (and you don't have a vacuum advance), then I'd suspect carb adjustment. It could also be a vacuum leak, but usually that will act up at idle unless the leak is at the base of the carb. 
Dean
'47 CJ2A "Mud Hen"
The less the Power the More the Force
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heviduty Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan. 2022 at 12:59pm
drm101; 
  I’m sorry I didn’t make myself clear, the miss doesn’t go away when I stomp on the gas.    What I meant was that after I slow down a bit and the miss just goes away that I can then stomp on the gas and it will fire on all four and pull hard , running very well at full open throttle until again getting up to around 55 mph. 

 It runs good at about 50.   Push it to 55 and a single cylinder stops firing.    Only one.   It’s not random but a constant dead hole.  It will continue this running on only three cylinders cruising along and I think it would maintain almost 55 for a long time.    The fourth cylinder never fires like this.  Then if I back off the throttle just a bit, let the speed drift back down to about 50  the miss goes away.    When this correction takes place it needs to be running at this lower speed for ten seconds or so.    It doesn’t correct itself immediately at the lower speed.      THEN  after it has slowed and is running just below the speed where it cuts out it runs very well
    If at this fringe RPM when it’s running very well I can then stomp on it and the engine reacts with a slow burst of speed accelerating nicely under full load for quite some time until I once again cross the threshold where it cuts back to three cylinders.   
    I understand that points or valves floating is constant with RPM and not load dependent.  My concern is that I can not identify a miss or stumble unless the engine is loaded.    
    I ran a twin injected small block boat offshore for years that I knew had a dead hole miss and got compliments all the time on how my engines sounded.  Not once did someone other than myself notice a problem.    It sounded good at idle and under load the miss got lost in everything else happening.   
   Unless you knew how to read the engine monitoring systems  you would never know.   
    The prime monitoring system in my Jeep now is my ear and it ain’t as good as it was.   
      I might be running a little lean perhaps. I’ve thought the spark plug color looked good but ….      I was fighting an overfueling condition early. At that time I was carbon fouling plugs.   In my mind anything other than black was good.  It might be showing a little lean. I’ll give that a closer look.    It’s easy enough to reset the metering rod now that I have the tools I just might try opening it a tiny bit more.    That’s a good thought.   Thanks 


Edited by Heviduty - 10 Jan. 2022 at 1:02pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heviduty Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan. 2022 at 7:07pm
Fixed it.   Update in original post.   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cpt logger Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan. 2022 at 11:44pm
Why could you not post that here in this post? Why make us go back to the original post?

Spoiler: It was the metering rod adjustment.

How hard was that?

I am glad that you found the problem & were able to fix it fairly easily. Good show!


Edited by cpt logger - 14 Jan. 2022 at 11:45pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jan. 2022 at 12:18am
  Well, Logger, ya gotta give him credit for one thing - he did let us know what fixed it. About 2/3 - 3/4 of the time, these newbies just disappear after 2-3 pages of guesswork and deliberation, and never tell us what the problem was, or Heaven forbid, say “Thanks”
BW 
It is NOT a Jeep Willys! It is a Willys jeep.

Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You!

We Have Miles to Jeep, Before We Sleep.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heviduty Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jan. 2022 at 12:59am
I’m sorry I didn’t do it your way logger. 
 In another forum that I am active in its customary to change the title to include “update” when there has been a resolution. it clues the watchers in that there has been an update AND a reader just needs to scroll down to the end of the original post. It’s really easier to simply scroll the original post to read update.   Adding a new response gets the update possibly buried in pages of responses.        Anybody wanting an update , it’s one page one.     
    I did this and then realized this forum might operate differently so I quickly dropped a clue.    
       Sorry if I offended.  Not my intent.       I did want to give back to this forum what info I could.        
      Thanks again 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cpt logger Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jan. 2022 at 7:33pm
No, you did OK. I was out of line.

I do appreciate you letting us know what the issue was. I was very tired & unusually for me, (I hope), a bit cranky.

I do not mean to offend. I am on a few forums & have not seen that system....Yet.

I will "Lighten up".


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