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Pulled spark plugs to find the mis....

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1958 rambler super View Drop Down
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    Posted: Jan/26/2022 at 5:41pm
Hi everybody, I'm trying to find out why the 195.6 is misfiring intermittently, I researched online and read there are three types of misfires.... intermitent or constant misfires in one cylinder, intermittent or constant misfires in numerous cylinders, and intermittent or constant misfires in adjacent cylinders, but the 195.6 is a inline six so the last catagory doesn't concern my problem... I tried spraying carb cleaner around the intake, thinking the flammable carb cleaner would increase the rpms, but it didn't increase, so I geuss there's no vacuum leaks around the intake, I also sprayed some right down into the carb and it almost killed the engine, so I don't know what that meens, I also tried the trick of pulling the spark plug wires one by one and seeing if sound of the engine changed and it sure did, each time, but the intermittent mis was still "cuffing" here and there.... The engines a rebuilt engine, I did the valve adjustment a couple months ago so I geuss the valves are fine, the coil is new, spark plugs are new, spark plug wires are new, the wire from the coil to the dist is good as far as I can tell, the dist cap isn't cracked, it has a new rotor and new points inside, the points are gapped correctly.... I'm sure the dist cap is turned to the right spot so the timing is good, but last time I tried to get it jjjuuuuussst right I noticed the rpms would rise higher and higher, should I disconnect the vacuum advance tube from the side of the dist to stop the rpms from rising and try again? Maybe the dist is worn out? It's the original delco Remy dist... This problem has been present with three different carbs on the engine by the way, the current one has a brass colored fitting near the choke that has vacuum suction at the fitting I can feel it when I put my finger over it, the engine does seem to run a bit better after its plugged, but the misfire is still cuffing here and there.
What do you guys think? 


Edited by 1958 rambler super - Jan/26/2022 at 5:44pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rgsauger Quote  Post ReplyReply Direct Link To This Post Posted: Jan/26/2022 at 11:25pm
Look up how to set timing with a vac advance distributor.   Disconnect  The vacuum advance line from the distributor and put a plug in it so the engine does not have a vacuum leak. With the vacuum Advance disconnected check your base  timing and then advance the throttle to 2500 or so  to check your maximum timing and also the mechanical advance mechanism.  

 Then reconnect the vac line and adjust the engine RPM down as needed  using the adjustment screw on the side of the carburetor linkage.  You always set timing with the vacuum advance disconnected.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rgsauger Quote  Post ReplyReply Direct Link To This Post Posted: Jan/26/2022 at 11:26pm
I prefer manifold vacuum source vs ported.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/26/2022 at 11:47pm
Valves are very unlikely to cause an intermittent misfire. If bad enough (I'm sure they're not) you might have a repetitive lumpy idle, bump bump bump... or something. Mechanical things tend to not get intermittent subtlely. 

That leaves carburetor, or ignition...

Does this misfire happen only at idle? Or at speed? If you cruise steady flat and level 45 mph in 3rd, does it misfire then? How about wide open throttle? Or just idle.

Lean engines act badly. Rich engines are stupid and smooth and sluggish, drunk on fuel. So Back out the idle mix a turn or more see if it improves. If not, move on to ignition.

Is each electrical connection bright clean shiny metal tight enough to tug on, hard? No wires wrapped around screws with a nut and no washer? Crimped connectors you can pull the wire quite hard and it should not come out or wiggle.

Is the electrical connect to the points one of those craptacular "slide in" types? Or does it have a stud with a nut and captive toothed lock washer? The slip-on kind are CRAP. Blue Streak used to be good, are they any more? Dunno.

Wiring has to be good all the way back to the battery (power source). 


Spark timing can do weird things and even misfire, but usually there's other weird side effects. One way to ball-park it is to loosen and rotate the distributor 10 degrees one way, see if it improves/worsens, back to 0, then 10 the other. None of these are fixes, but tests. When all's well, it will definitely change RPM, but not much more. But if somehow timing is really off, making it worse might tip it over into bad misfiring or something. My estimation is that timing isn't the problem, and that you have an electrical intermittent (if we're taking bets).

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LakesideRamblin Quote  Post ReplyReply Direct Link To This Post Posted: Jan/27/2022 at 1:23am
Double check or replace all spark plug wires and distributor wire again.  I had this same mystery years ago and a "good" spark plug wire turned out to be bad.  Drove me crazy but an easy fix.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/27/2022 at 10:30am
Originally posted by LakesideRamblin LakesideRamblin wrote:

Double check or replace all spark plug wires and distributor wire again.  I had this same mystery years ago and a "good" spark plug wire turned out to be bad.  Drove me crazy but an easy fix.

Isnt it better to check first before filling the parts cannon?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jan/27/2022 at 11:08am
Easiest way to check for an ignition problem is to use a magnetic PU timing light on each ignition wire to see if the strobe is flashing consistently. Also rev the engine a little as some ignition problems only show up at cruise RPM's.
This is not checking timing, just using the light it to determine consistent spark to each cylinder. If you have consistent spark, you have eliminated this as a problem without replacing anything.
Takes 15 minutes. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wittsend Quote  Post ReplyReply Direct Link To This Post Posted: Jan/27/2022 at 11:31am
Yes, as mentioned a quick check in the dark for stray sparking can reveal a potential misfire. The darker the better but REMEMBER THERE ARE FANS, BELTS AND ACCESSORIES SPINNING AND ONE NEEDS TO BE CAREFUL. VERY CAREFUL.

 The point gap should be .016. If the distributor is loose you should be able to  see it by holding the rotor and gently push/pull it in line with the lobe the points are open on. You should be able to notice movement at the points if the distributor is loose. Just be careful you are not rotating the rotor as this will cause the points to ride down on the lobe and gap will close giving the illusion that the distributor is bad when it might not be.

These are from my Glenn's manual 1958 settings. Get the engine warmed up and the idle set to the proper speed (450 RPM in Neutral). Note that in later years the idle was 550 RPM and may give a smoother idle.
 Disconnect the vacuum advance plugging the line to prevent a vacuum leak. Set the timing 5 degrees BTDC.
  This is important. If the timing is too advanced the RPM will drop when timing is set properly. Likewise if the timing is too retarded the RPM will increase when set properly. What can happen is what looked like proper timing or RPM shifted because the centrifugal advance is also advancing (or retarding) as RPM changes. It is a bit like a dog chasing its tail. So..., you have to set timing, go back and correct the RPM and do this a number of times until you get the proper RPM - at the proper timing.

I have often found what seems like a miss can be too high a fuel pump pressure (or too high a float level) and this causes fuel to splash out the vent and alter the mixture richness. Careful observation of the carburetor vent can reveal this.


Edited by wittsend - Jan/27/2022 at 11:48am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1958 rambler super Quote  Post ReplyReply Direct Link To This Post Posted: Jan/27/2022 at 10:46pm
Ok, so to answer the question, does the miss happen only at certain rpms? No, it happens all the time. sadly, I have never been able to drive the rambler, I been working on it since dec7 2021 and still have yet to enjoy driving it, so no, the misfire is not happening  only at 3rd gear ect but at all times when the engine is running. 
I went out and bot a timing light and a vacuum gage, I'm happy I finally did it, 107$ well spent. So, following most but not all of your direction from your posts, I disconnected the vacuum from the dist and loosened the dizzy and turned it either way till I found a good spot where the engine seems happiest, but I didn't bother turning the screw on the carb, but anyways, it didn't make the miss get any better so I moved on, (man the engine sounds bad with the new YFA instead of the weber!! It sounded so happy, even with the miss) I used the timing light I bot, a simple inductive one with the flashing light that pulses with each electric jolt, and saw the following.... #1 cyl was pretty steady, maybe even completely steady unless I didn't notice a extra flash or double flash, #2 cyl seemed the same, #3 cyl steady with a extra flash here or there#4 the same as #3, #5 cyl completely crazy machine gun flashing, and #6 lots of flashes but not as nuts as #5, maybe steady but at a double pace, and the coil wire was the same completely crazy machine gun flashing, that's probably normal. I switched the #5 cyl wire with the #6 wire and nothing changed like I thought, and I even swapped out the new NGK plug wires with the super old wires that came with all the stuff for the disassembled rambler parts, and observed the same performance with the timing light. I even thought to see if the spark plug wires might be too close, but they seemed to have enough space apart... I set up the vacuum gage at the manifold and observed a steady vacuum of 20(?) so I suppose there is no vacuum leak according to what I saw, which was nice and interesting to exp.
I wondered if I should disassemble the dist to see if there was something wrong with it but changed my mind, thinking I don't know if the evidence really points to that action to take, so I opened it up and followed the suggestion to carefully wiggle the rotor back and forth being careful not to twist it and I found it to be steady and not wo ble back and forth, and the points were opened like you said and I didn't see any noticeable wobble, unless I missed it. After that I took a look to see if there was any obvious reason the #5 wire was lighting up like that, I looked and saw that the wire the coil attaches to and travels inside the interior of the dist was angled high up, and maybe it might be doing some weird electromagnetic conductive stuff to the #5 plug wire tower which was close by, so I carefully undid some of the fasteners and lowers it down, but it did nothing to change the problem or change the flashing rapid light seen when using the time light, also,  cleaned up some of the fasteners the coil wire attached to the dizzy, but lal the other ones are clean and shiny too, so nothing wrong there, and I checked and everything is all tightly secured together.. Lots of the wires are old, basically all of them, but I did extensive continuity testing as per trout Willy's advice with the multi meter and found all the wires to be healthy, so no problem there, all of the wires in the engine compartment and the dash got tested and had good continuity, except I didn't test the wires going back to the trunk and tail lights ect, but those workfine, I've seen the brake lights work ect ect, 
I checked to see if the points in the dist were gapped at the appropriate. 16and it was. 16, so nothing wrong there.
I tried googling why one cyl would give out a reading like that on a timing light but I got no good info to give me any answers.... 


Edited by 1958 rambler super - Jan/28/2022 at 2:43am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wittsend Quote  Post ReplyReply Direct Link To This Post Posted: Jan/28/2022 at 10:37am
It was wise to change wires and plugs and to check for separation. The wire internal to the distributor that you attempted to lower was it in the vicinity of the problem 5 and 6 distributor terminals? If so it might still be a contributor to the problem.

You might try looking at the inside of the distributor cap for a crack. They can be difficult to see some times. Make sure you have good light, use a magnifying device (close up reading glasses, a magnifying glass, etc.). If you can get some light pressure with opposing thumbs moving outwards it can sometimes help to open and reveal a crack if one is present. Work the thumb pressure around in difference locations.

Also observe the distributor cam. The lobes the points ride up on should all look the same. I have seen baked-on grease affect the point gap on a certain cylinder.

Do be careful how the inductive clamp is positioned. It might be picking up stray spark from other cylinders.
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