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Old 07-06-2022, 07:54 PM
keithems keithems is offline
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Question #4 plug misses...

nstalled a new carb about 3 yrs ago...

runs well - when it runs..which is not always..

1. often the #4 plug [trans end of the engine] does not fire..usually if i fool around enough and replace the plug ..and/or the wire...i can get it to go.. : )

recently noticed that if i pull the wire and then lay it loosely on the plug..i can see a gap between the wire and the plug and then it fires..so i am wondering why...

do i have to do a complete tuneup? or maybe it's just the cap and/or rotor?

pls let me know, as i'm not getting any younger, and i remember last time i did condenser, points, etc. it was a real pain..i'm only using the motor 50-100 hrs / summer [year], and mostly for in and out of the harbor..no long cruises..

there are more questions but i'm over the limit -- so let's solve this one and then i can post more
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Old 07-06-2022, 08:24 PM
Dave Neptune Dave Neptune is offline
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When you hold the wire away and get the plug to work indicates a few things.
First question is what plug are you using and is the gap set?

Another indication of the above is a poor spark which leads me to the points. Did you set the points by gap or dwell? These old distributors are really old and the cam that moves the points is probably worn so setting by "gap" can result in poor coil saturation and a weak spark. The #4 plug is problematic to this issue as it tends to run rich because it is a downhill feed and gets the excess fuel.

Third it could be fouling so have you tried to lean down the carb idle by opening the air screw?

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Old 07-06-2022, 08:59 PM
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see next -- still relearning how this site works
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Last edited by keithems; 07-06-2022 at 09:09 PM. Reason: corrected on next post
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Old 07-06-2022, 09:07 PM
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Thank you for the quick reply!

Quote:
Originally Posted by Dave Neptune View Post
When you hold the wire away and get the plug to work indicates a few things.
First question is what plug are you using and is the gap set?


yes -- i've tried them all -- champion 12 yc and also the auto lite 85 and ngk..which were recommended because they are hotter..

gap is set at .035

u can't believe how many plugs i have lying around cuz i've tired to clean the old and install new....mostly not helpful for very long..

Another indication of the above is a poor spark which leads me to the points. Did you set the points by gap or dwell? These old distributors are really old and the cam that moves the points is probably worn so setting by "gap" can result in poor coil saturation and a weak spark.


haven't touched points since motor was removed and reinstalled in 2012...don't use the motor much -- 50-100 hrs per year - in and out of the harbor only....and wanted to avoid fooling with the points..but i will if i have to..not getting and younger, u know...

The #4 plug is problematic to this issue as it tends to run rich because it is a downhill feed and gets the excess fuel.

interesting...always learn something from you...i assumed it ran cold cuz when i redid engine i reinstalled water spray per don's instructions, so i think it's getting lots of cold lake erie water sprayed on it..motor typically runs fairly cool

Third it could be fouling so have you tried to lean down the carb idle by opening the air screw?

no -- the opposite...air screw has to be almost full rich to get a good idle..so i richened it to hopefully cure the fouling..to no avail...but i can't lean it very much---1/4 to 1/2 turn out from full rich to get a smooth idle...

and that was my 2nd question!

keithems
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Old 07-06-2022, 09:29 PM
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Do any of the plugs have an "R" in the plug number. That indicates a resistor type. What you are doing by holding the plug wire away is increasing the resistance which backs up the current a bit until there is enough energy to spark across the gap. I recommend Champion RJ12C or equivalent.

Might be a good time to convert to an EI as converting it is easier than adjusting the points until the proper "dwell" is achieved.

Another point is since it has been so long since you did the points the timing is probably a bit off too. This too is another reason to go EI.

Have you checked to see that the C-advance is working smoothly?

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Old 07-06-2022, 10:34 PM
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Quote:
Originally Posted by Dave Neptune View Post
Do any of the plugs have an "R" in the plug number. That indicates a resistor type. What you are doing by holding the plug wire away is increasing the resistance which backs up the current a bit until there is enough energy to spark across the gap. I recommend Champion RJ12C or equivalent.

Might be a good time to convert to an EI as converting it is easier than adjusting the points until the proper "dwell" is achieved.

Another point is since it has been so long since you did the points the timing is probably a bit off too. This too is another reason to go EI.

Have you checked to see that the C-advance is working smoothly?

Dave Neptune
yes-- i usually have used rj12yc, i think--they're the plugs moyer recommends

like i said some of the auto stores recommended i try the autolite 85 or the ngk plugs because they are hotter...nothing seemed to make any difference. also can't always get the champions around here.

haven't checked the c advance at all..i always assumed it was the problem with that cylinder or the valve causing the plug to foul

only recently noticed that it fires when wire is only laying on or near the plug

i guess i'll have to consider that e i, but i don't want to make that investment until i'm pretty sure it will fix the problem

also -- if it needs new points / timing, etc. why do the other 3 cylinders run fine?

thank you again for your help.
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Last edited by keithems; 07-06-2022 at 10:40 PM. Reason: plug brand corrected
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Old 07-06-2022, 10:42 PM
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where do i get the electronic ignition?
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Last edited by keithems; 07-06-2022 at 10:42 PM. Reason: typos
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Old 07-07-2022, 07:33 AM
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You can get one from MMI or Indigo, both are excellent units. I do like the new Indigo unit a bit better only because it has an LED indicator on the unit that shows it is switching which eliminates some guessing as to it working.

Ten years on a set of points is a very long time and they must be really worn by now.

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Old 07-07-2022, 07:49 AM
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The #4 cylinder gets the least cooling and thus more wear as well as the fuel that puddles goes "down" to that cylinder. It is kind of a weak link or the first to cause problems. Is the #4 fouled wet, sooty or oily? Often a hotter plug will help with the fouling and so will a better ignition spark from an EI.

Check the C-advance by twisting the rotor, it should move smoothly against the springs and return just as smooth. It should be lubed from time to time to keep it so in a marine environment.

If you stick with the points do get ahold of a dwell meter if you can still find one. It is a pain to set the points by dwell and the only way to get truly good results. With the EI you install and set the timing. The timing needs to be set either way and every time you touch the points as well as compensating for wear as the wear changes the timing. There is no wear with an EI so once set your done and the timing won't change as time goes by.

Have you ever checked the compression?

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Old 07-07-2022, 12:08 PM
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The trick of making a gap between the plug and plug wire is one way to get fouled plugs to fire. I found that out many years ago.
In my experience #4 isn't the hottest plug, it is the coldest and most prone to plug fouling and sticking valves. Also if there is any way water is leaking into the exhaust or intake, it ends up in #4.
Electronic ignition will certainly help, but it might be covering up a problem that may just keep getting worse. I have been there and done that
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Old 07-07-2022, 03:38 PM
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Quote:
Originally Posted by joe_db View Post
The trick of making a gap between the plug and plug wire is one way to get fouled plugs to fire. I found that out many years ago.
In my experience #4 isn't the hottest plug, it is the coldest and most prone to plug fouling and sticking valves.
so can you suggest a way for me to make that gap that would keep the plug wire on in rough seas?


Quote:
Originally Posted by joe_db View Post
Also if there is any way water is leaking into the exhaust or intake, it ends up in #4.
how would i determine if that is the problem?

Quote:
Originally Posted by joe_db View Post
Electronic ignition will certainly help, but it might be covering up a problem that may just keep getting worse. I have been there and done that
also fwiw...the next suggested thread is from someone with a problem identical to mine:

https://www.moyermarineforum.com/for...ead.php?t=1241
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Last edited by keithems; 07-07-2022 at 03:39 PM. Reason: added url for thread cited at end
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Old 07-07-2022, 03:50 PM
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All good advice. If it were me I would do one thing at a time and usually inexpensive. First find TDC and change and set points. At high point on cam set gap at .025 and then see if #4 fires. If it does then dynamic time the engine and then possibly upgrade rotor and cap and you are roughly right. Next or first I would change out #4 wire - may be old and have developed more internal resistance requiring the bigger coil load ie air gap.

If this doesn't work you have great advise to follow. If you go the EI route remember to get new coil with proper resistance.
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Old 07-07-2022, 03:56 PM
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The #4 cylinder gets the least cooling and thus more wear as well as the fuel that puddles goes "down" to that cylinder. It is kind of a weak link or the first to cause problems. Is the #4 fouled wet, sooty or oily?

yes -- all of the above...but the motor does use a bit of oil, and i load the #4 with mmo to keep it working

Often a hotter plug will help with the fouling and so will a better ignition spark from an EI.

yes -- i may have to follow your suggestion and get EI

Check the C-advance by twisting the rotor, it should move smoothly against the springs and return just as smooth. It should be lubed from time to time to keep it so in a marine environment.

will do...

If you stick with the points do get ahold of a dwell meter if you can still find one. It is a pain to set the points by dwell and the only way to get truly good results. With the EI you install and set the timing. The timing needs to be set either way and every time you touch the points as well as compensating for wear as the wear changes the timing. There is no wear with an EI so once set your done and the timing won't change as time goes by.

in the moyer manual, don says i can replace points without removing the distributor -- seems easy enough -- hope it is...so today i intend to remove the cap to see if it's damaged [my first inclination], check the advance & springs as you suggest, and probably replace points, condenser, rotor and cap as soon as i come up with the parts...also per the thread i cite below, i may try champion rj-8c's, which in fact are the ones the original a-4 manual recommends..[i understand, there were no rj-12c's at the time]

here's the url for the thread cited above...

https://www.moyermarineforum.com/for...ead.php?t=1241

Have you ever checked the compression?

nope -- hopefully that's not the problem, cuz i'm not up for doing another rebuild...


Dave Neptune

thank you again
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Old 07-07-2022, 04:04 PM
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Quote:
Originally Posted by Sam View Post
All good advice. If it were me I would do one thing at a time and usually inexpensive. First find TDC and change and set points. At high point on cam set gap at .025 and then see if #4 fires. If it does then dynamic time the engine and then possibly upgrade rotor and cap and you are roughly right. Next or first I would change out #4 wire - may be old and have developed more internal resistance requiring the bigger coil load ie air gap.

If this doesn't work you have great advise to follow. If you go the EI route remember to get new coil with proper resistance.
yes -- i've replaced wires a zillion times...have a whole pile of them, plus a box with a new set...doesn't solve the problem, unfortunately...have also replaced plugs a million times..will try some rj 8's today per the following thread [looks like a problem identical to mine]:

https://www.moyermarineforum.com/for...ead.php?t=1241

thx for the advice re. a new coil...didn't realize i'd need one if i get the e i
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Old 07-07-2022, 11:05 PM
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One request...do you have an in-line spark plug tester?

I would be very curious to see what the #4 results are using an in-line spark plug tester before and after the plug switch with clean gapped plugs. Perhaps you would see a difference in the test light pattern which will help with your decision making?
https://www.youtube.com/watch?v=UymD_i_9Q9Y

I understand the interest in a hotter plug in number 4 for fuel pooling there, though the cooling ports may make this a hotter than average cyclinder (usually seems to be the first cylinder to show temp increase on my A4). Not sure how this is for engines with the Thatch(?) mod.

If a hotter plug fouls less, the 8 vs 12 swap is baffling assuming the 12 is a hotter plug. And you are treating #4 regularly with MMO so that could cause faster fouling with a cooler plug right?

I just want to know more about the pattern of spark reaching the #4 plug either way. And I have not yet seen this explored here. Test across plugs even make a phone slow mo video and compare. May help you with next steps. Cheaply. Even though you are not getting any younger : )

Best with isolating the problem.
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Old 07-08-2022, 09:12 AM
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i followed the url cited above....if you want to know more, i suggest you click on it and read all the responses..including don's

https://www.moyermarineforum.com/for...ead.php?t=1241

last nite i found an old J 8 C in my plug collection, so i tried it out...sure enough, problem solved! also tried a R C 12 YC NOT a R J 12 YC... that one also ran well...does anyone know what the difference is?

also pulled off the dist. cap and rotor....they were well past due, so i replaced them, but that didn't seem to improve performance beyond what the switch to the j 8 did. next will change the points and condenser and check on the operation of the advance springs.....maybe check the timing....hopefully that will be it for a while..

over the years i had consistently tried using hotter plugs...with no lasting improvement. the post i cite made me consider a cooler plug, which so far seems to be working....

also, i repeat, the original a-4 manual i have from universal, the manufacturer, specifies the J 8.
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Old 07-08-2022, 07:01 PM
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Thanks for update....great you have her running...congrats...

I posted back to you last time after carefully reading the thread you left (thankful), Don's post especially and frankly landed me with more questions than answers. My last post clearly fell short if you thought I had not read the thread.

I took little to no comfort in Don's post, because, well to paraphrase, he did not find resolution, and the manufacturer speculates that a porcelain crack or manufacturing defect lead to the observed resistance. Emphasis mine. (am I missing another post or thread--I admit that is often possible).

"We finally got through to Champion Technical Service for an explanation of this problem and more or less drew a blank. They could only speculate that the plug probably had a hairline crack or other defect in the internal porcelain insulating material. Whatever the exact nature of the defect, the insulation quality of the porcelain could apparently control the secondary discharge with the increased resistance imposed when the lead was held away from the plug, but would break down and follow some other path to ground when the lead was connected to deliver the entire secondary discharge."

I wish I could place your old plug on a volt meter and take a resistance reading. For fun I am going to check all of mine. As other commenters note, fouling alone will cause resistance. This does open up an easy maintenance/monitoring point.

Respect your going back to the distributor/advance work and making sure things are bright, tight, and dialed in there. I am always learning and one of the lessons this site keeps teaching is being patient systematic and meticulous when solving these inverse problems where the causes can be nested in a chain of systems. Collecting diagnostic data in creative ways is one of the learning points many here so freely proffer. Thankful. Best with the balance of your work.
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Old 07-08-2022, 09:40 PM
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thank you

at my boat tonite..with the new rotor and cap, figured i'd try the rj12 again..

no good

so put the j-8 back in, and all was well

no one mentioned it but the r stands for resistor...maybe if you have all kinds of electronic gizmos that would matter...but this is a sialboat..remember?

so the r - resister makes for a weaker spark

so maybe the reason the manufacturer originally recommented the j 8 is cause it has no resisitor...and maybe that's why it';s s-working now..

also i noted another thread siarecommended autoliek 437 ..agaoin has not resisitor..i'm gettin one tomorrow..

frankly i think the resistor is the issue...

just liek we avoid ethanol, etc. may need ot avoid resitor equip[ped spark plugs....

anyhoo--alls well that ends well

sorry -- dyslexia -- mayve time for this site to have a spell chacker?
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Old 07-09-2022, 07:31 AM
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See post #5 regarding "resistor" plug. The resistor does not weaken the spark it "concentrates" it for a stronger spark across the gap.

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Old 07-09-2022, 08:57 AM
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My friend....

There is no comparison between your knowledge level on these matters and mine -- yours is vastly superior.

that said..on the following page i've cited so often [above], david masury cites autolite 437s as having provided superior performance to the champions. so i ordered one to try out -- will get it today or tomorrow. i did note that the 437 is also a non resistor plug.

like i said, my original a4 manual recommends the j 8 -- NOT the r j 8...who knows? i rooted through my old spark plug collection and there were many r j 12 yc s ...but only 1 j 8. so i put in it..it worked!..and yes i've been down
this road too often..something seems fixed, and then it's not. but last night I did run my a4 at the dock at cruise power...with occasional periods at max ..for over 30 minutes..not a single hiccup! so today i'll get a fresh j 8 to put in to compare with the autolight 437. also, first thing i tried last nite was to rplace the j 8 with an r j 12...to see if it was the new rotor and cap with caused the improvelen. it wasn't --the r j 12 didn't fire.

meanwhile, reading your response just now, i wondered how i could have been so dumb as to think a non resistor plug would perform better than a resistor plug.

so i went back to check my google search history, and here's what i found:

https://automotivewave.com/resistor-...r-spark-plugs/

that is a very long and detailed explanation, but here is a short summary:

About 7,870,000 results (0.49 seconds)

Most resistor spark plugs use a monolithic resistor, generally made of graphite and glass materials, to filter the electrical voltage as it passes through the center electrode. Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark.

What is a Resistor Spark Plug? - NGK.com

also there are many reviews from guys with older engines of all types -- many from the 1940's and 50's, which of ocurse is when the a4 was developed--complaining that their engines will not run on resistor plugs.

so i conclude -- rightly or wrongly -- just like our a4s were not designed for ethanol and clearly run better on ethanol free gasoline -- which i go to great lenghts to obtain near my house nad then drive it 8 miles or so to my boat..they were not designed to run on resistor plugs and have no need for them, unless maybe you have sensitive electronic components like electronic ignition, electric fuel pump, auto helm, gps, fancy radios...whcih i do not.

and the reason in my case it's the #4 cylinder which is most problematic, it's likely cuz it's farthest to the rear, at the bottom of the slope, etc., etc. it's also the one i have to infuse frequently with mmo and most likely to have valve problems.

stay tuned....i'll be honest enough to report if this solution really works out or is just anther trick the marine gods like to play on amateurs like me.
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Old 07-09-2022, 09:19 AM
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My last engine had several problems that interacted in odd ways and it made troubleshooting very hard. I suspect this might be the case here.
To start with some basic principles:
1. Unless they are defective, pretty much any spark plug that fits into the engine and has around the right gap will work for awhile. Cold plugs will eventually foul and too hot plugs will eventually cause pre-ignition and or damage themselves. None of that happens quickly, it takes some time to foul plugs or overheat them.
2, Defective spark plugs do exist. There are counterfeit NGKs around, I had a couple break apart and drop pieces into the cylinders in my car I recently had a Champion develop a leak through the porcelain. It still worked, but that cylinder was low on power.
3. The conventional points ignition has numerous places where parts can fail outright or subtly get worse.

I would do the following:
1. End-to-end check of the ignition and replacement of the wear components. This is cap, rotor, points, condenser, and wires. My condenser was acting up recently and it was not especially easy to figure out. The engine got hard to start, but the condenser passed the tests I read about using my VOM. I replaced it anyway and my issue went away. Coils can go bad too, see check # 2 below.
2. Check for a nice snappy blue spark from the coil wire to ground on cranking.
3. Now put the coil wire back on the distributor and check for a nice snappy blue spark from each plug wire. Plug wires can go bad.
4. Get 4 new plugs and test them out of engine on the wires. Make sure they all have a nice snappy blue spark. I use an oven mitt to hold them and not get shocked or leather gloves.
5. Make sure the timing is correct. I use a light, but you can eyeball it pretty close.
6. Now before the plugs go in we'll do a couple basic engine diagnostics.
7. Check compression on all 4 cylinders.
8. While that is going on be alert for water getting into or spraying out of any of them.
(note the cooling intake should be OFF for all this)
9. If all this checks out, put everything together, turn the gas on, turn the cooling water on, and run the engine for a bit. I would let it idle and then run under load for about 15 minutes.
10. Take the plugs back out and look at them.
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Old 07-09-2022, 10:32 AM
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. . . and the reason in my case it's the #4 cylinder which is most problematic, it's likely cuz it's farthest to the rear, at the bottom of the slope, etc., etc. it's also the one i have to infuse frequently with mmo and most likely to have valve problems.
Valve problems? What valve problems? If there are valve problems, they won't be solved by fiddling with the ignition system.
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Old 07-09-2022, 10:56 AM
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Valve problems? What valve problems? If there are valve problems, they won't be solved by fiddling with the ignition system.
of ocurse not...but if 3 cylinders are wrunning fine but one is not -- usually the #4, due to its location -- it can be ignition or a sticking or stuck valve.

a4 is notorious for sticking valves, malfunctioing valves, etc. that's why not long after getting a used a4 i had to do a valve job and have doen several since. and the only time i've had to have a rebuild is when a frozen valve caused the camshaft to break.

also why don recommends you use mmo like it's holy water
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Old 07-09-2022, 11:21 AM
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Yeah well, the A4 is also notorious for exploding when you turn the ignition key so internet or dock rumors might not be the best diagnostic tool. Mine doesn't have valve problems, never has since I've owned her and yes, per Don Moyer's advice I add 1% MMO to my fuel.

But you said "it's also the one (#4) i have to infuse frequently with mmo and most likely to have valve problems." So the problems are unique to #4 and it is getting direct treatments of MMO different from the rest and way different than 1% MMO to fuel ratio and despite everything you've tried so far the problems persist. Other than being downhill, what's different in #4 than the rest of the engine? From what I'm reading directly from you, likely valve problems.

Why not determine if there are actually valve problems in #4 before chasing ignition zephyrs? As a first test, have you checked the compression, dry and wet, warm and cold? How does it compare to #s 1-3?
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Old 07-09-2022, 03:13 PM
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Yeah well, the A4 is also notorious for exploding when you turn the ignition key so internet or dock rumors might not be the best diagnostic tool. Mine doesn't have valve problems, never has since I've owned her and yes, per Don Moyer's advice I add 1% MMO to my fuel.

But you said "it's also the one (#4) i have to infuse frequently with mmo and most likely to have valve problems." So the problems are unique to #4 and it is getting direct treatments of MMO different from the rest and way different than 1% MMO to fuel ratio and despite everything you've tried so far the problems persist. Other than being downhill, what's different in #4 than the rest of the engine? From what I'm reading directly from you, likely valve problems.

Why not determine if there are actually valve problems in #4 before chasing ignition zephyrs? As a first test, have you checked the compression, dry and wet, warm and cold? How does it compare to #s 1-3?
just wondring if you read any of my posts from the a m.

as of now, running great wiht the non resistor j 8 on the #4 cylinder.

points and condenser arriving tomorrow, and i will install shortly.

if you look at my join date you can see that for the most part i've had a long and good history with the a4; not on that much cuz there's no need to be.

and yes, i put mmo in the fuel and the oil; only occasionally add a shot to the #4. it does not hurt naything--just makes her smoke like an old diesel and a few nincompoops glare at me for a while.

you may have read a few years ago [many more, actually] that when bill clinton was preparing for the pres debates, he went through buffalo and stopped to load up on beef on weck sanwiches at charlie the butcher's.

charlie has a sign there next to a stale sad looking bunch of rolls. it says "i'm a butcher, not a baker."

well, i'm a sailor, not a motor guy. the purpose of my a 4 is to get me in and out of the marina...maybe the harbor, but not really necesssary, and up and down the canal and throguth the lock going between winter storage and summer marina. as long as it can do that, i'm good.

excuse my dyslexia
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