Spark Plug analysis

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2017: Spark Plug analysis
Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick in Florida on Wednesday, February 08, 2017 - 06:08 pm:

As per the suggestion of several members I removed my Champion spark plugs and checked them to see if they might be the cause of my rough running engine. They are all gapped at .025:

Cylinder 1 spark plug is coated in a thin, dry layer of powdery soot overlying a thin layer of hard carbon.



Cylinder 2, 3 and 4 are also coated in a thin, layer of dry powdery soot overlying a thin layer of hard carbon, but these also have a white area at the points where the spark from the center electrode makes contact with the ground electrode. I only attached 2 photos of the cylinder 4 plug, because the plugs for cylinders 2,3 & 4 look almost identical



I easily removed the soot and hard carbon with a Dremel Tool equipped with a brass wire brush. After they were cleaned, all the edges were sharp and there appeared to be no heat distortion, pitting, erosion, or rounding of the edges of either the center electrode or ground electrode.

Can anyone tell me what this tells me about my engine or my fuel mixture? Thank you. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick in Florida on Wednesday, February 08, 2017 - 06:11 pm:

PS Photos were taken before cleaning. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, February 08, 2017 - 06:44 pm:

Jim
Waaaaaaaaaaaaaaaaaay to rich.
Just what one would expect from mixture control settings you initially described you were using in your other post on this problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Wednesday, February 08, 2017 - 07:20 pm:

Yep, mixture too rich. Try leaning out the mixture rod on the carb 1/8 turn from where you're running it now. If the car still runs well with no hesitation on acceleration, continue to go leaner, but in smaller, 1/16 turn increments. You'll know when you've gone too far when the car starts hesitating on acceleration, or starts feeling like it has an occasional, irregular miss during light throttle cruising. Good luck!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Wednesday, February 08, 2017 - 08:03 pm:

Some, not all, cars must have the hot air pipe installed or the plugs will get sooted.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Wednesday, February 08, 2017 - 09:13 pm:

Disagree. My plugs never look like that and I have not used a hot air pipe in many years. As Ford said, the hot air pipe is only necessary in cold weather.

Likely either the mixture is maladjusted or the float level is too high.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Coiro on Wednesday, February 08, 2017 - 10:23 pm:


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Thursday, February 09, 2017 - 09:10 am:

My personal opinion - with the simple carburetors from the Model T era and the short distances that many of us drive our cars, it might be a challenge to achieve the "normal mixture" look on your plugs without having other symptoms of running too lean, i.e., surging, popping, or overheating. I run as lean as I can without the above symptoms, and my plugs come out looking a little dark, but nowhere near as sooty as the ones in Jim's pictures. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Thursday, February 09, 2017 - 12:28 pm:

Hi Jim,

After looking at your plug pictures I concur with the recommendations to try a leaner mixture, that may be all that you need to do.

If a leaner mixture does not reduce the soot, OR the engine runs less well with the leaner mixture, you may want to investigate the coolant temperature after the engine has "warmed up" for 10 or 15 minutes; it may be running too cool and never really reaches Normal Operating Temperature.

Again, if a twist of the mixture rod is all that is needed, Hallelujah! Good luck with your project, Bill.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick in Florida on Thursday, February 09, 2017 - 12:34 pm:

My plugs are nice and clean and set at .025. I'm looking forward to installing them and seeing if it did the trick.

I will try turning the choke clockwise until it starts running rough and then turn counter-clockwise a little until it stops running rough. Before, I would turn it clockwise until it started running rough, then counter-clockwise until it started running rough, then set it right between the two points. Obviously, the point right in between is too rich.

The wax paper that originally came with the Champion X Spark Plugs says to set the gap at .025", which is what I did back in 2010 when I originally installed them, new. I have also read in my keyword research on the Forum that old timers used to set the gap the thickness of a Mercury dime. Also, I have a 1926 edition of "Dyke's Automobile and Gasoline Engine Encyclopedia" (the Chilton's of its' day), which says to set the gap at 1/32" (.03125"). Do you think that a wider gap would provide a longer (as in length, not time) and hotter spark that would, ignite and burn the atomized fuel in the cylinder more readily? Thank you all. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Thursday, February 09, 2017 - 01:54 pm:

A wider gap gives a weaker spark. Narrower gap gives a hotter spark less likely to foul. Champion recommended that .025" gap for good reason.

Modern cars have spark energy hundreds of times stronger than a Model T. They run .045".


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Mills_Cherry Hill NJ on Thursday, February 09, 2017 - 05:34 pm:

Royce...

You want to rethink that last? You and I generally agree on just about anything and I have always been game to try some of your 'hacks' on my 'hack' without fear or risk...

but...

If I were Jim, I would OPEN the gap to 0.032 if not 0.035. A wider gap always gives a cleaner burn PROVIDED your voltage is strong enough to jump the gap under compression. If Jim's car won't arc the wider gap then it is an ignition issue that may or may not be fixable. I always gap my take-aparts at 0.032 and I never have issues on any of the cars. That doesn't mean that I am right...just what seems to work for me...(I also run an A-25 in #1 on the '15 as that is the only way I could get the electrode on #1 to burn as clean as the others. (No wives tale there...I tried it, it made a difference) All of my cars also start on mag so right/wrong/indifferent, opening to 0.032" is apparently not a bad thing...

Jim,

I've tried to follow your commentaries on this...

- #1 'can' burn colder than the other three and that 'can' lead to a #1 that is always sootier than the rest...but never as bad as shown.

- What do you think your gas mileage has been with plugs this sooty? Seriously, I'd expect your MPG to go down by about a factor of 2 times for something that dirty that is dirty from a rich burn.

- You are in Florida, so a cold start is not your problem...(a nice problem to have). As you point out, lean out SLOWLY by moving a bit and counting to 10 before moving it again and until you start to miss...then open 1/4 turn. Clean the plugs and then go for a good ride. (at this point don't worry about how many turns from zero on the control knob this point actually is)

- If your car runs good on low, and starts to hiccup on going to high, just reach over and open the knob another 1/8th turn or so. When you get a smooth '0' to road speed this way, it is about the best you can get. Still soots up from there? And it is not an oil soot? Go back through your carburetor once again as too much gas is being sucked up and in,


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick in Florida on Thursday, February 09, 2017 - 10:33 pm:

I spoke to Ron Patterson this afternoon who suggested I check the float needle seat for leakage, as the gaskets for these are notorious for allowing gas around them even if the float needle provides a good seal against the seat. I sucked on the gas inlet with the needle closed and had a perfect vacuum, so I am certain my float needle seal is not the problem.

Ron also suggested that I remove the mixture needle and check for scoring by using my fingernail. I checked it and there was slight scoring and discoloration around the needle where it goes into the seat which could have affected the atomization of the fuel to air mixture. To remedy this, he advised me to take a scrap block of wood and drill a hole in it using a bit the same diameter as the needle shaft. The hole needed to be drilled at such an angle so that the angle of the needle was even with and flush with the flat side of the block where it came out. This is so that the a separate smooth block with sandpaper around it can be held against the hole as the needle, mounted in a drill is pushed through the hole with the entire length of the angled point against the sanding block which is held tight to the block, so that when the needle is turned by the drill, the sandpaper removes the scoring. I did this, first using 400 sandpaper for a short time until the scoring was gone, then brought the needle to a mirror-like shine using 1500 grit sandpaper. He said that some people incorrectly use their fingers to do this and wind up with a cupped point and a bigger problem than before.

regarding the fuel mixture setting, Ron said to start it, then turn it clockwise until it just starts to "lope" and a runs little rough, then turn it counter clockwise 1/8 to 1/4 turn until it runs smooth.

Lastly, he said he never sets the gap on his Champion X spark plugs less than .035 and has had cars where the gap needed to be set greater than .040. That .025 is too small a gap for the Model T, but that all T's are different and I will just have to experiment to find the best gap for my T, so I set my gap at .035 to begin with.

I just got the carb back together and installed it, along with the plugs. It is late and I'm tired, so I am going to wait until tomorrow to crank her up. I will let you know how it goes.

My thanks to Ron Patterson for taking the time to call me and troubleshoot my problem today, based on my above posts. I think he got to the root of the problem(s). Thanks also, to everyone who offered their advise. I will let you know how it runs tomorrow after I get her cranked up. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick in Florida on Thursday, February 09, 2017 - 10:40 pm:

PS. The first picture is of my #1 cylinder plug. Since all the plugs are covered in dry soot, I can imagine what the inside of my cylinders look like. Is there a way to clean out the cylinders without removing the head? Do you think that, with the fuel mixture and spark gap set correctly, the cylinders will blow the carbon soot out as it runs?

In the seventies and 80's I would occasionally spray water from a spray bottle into the carburetor of my '74 Camaro to clean out the cylinders, but I would never try this with a Model T without the concurrence of the experts on this forum.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, February 10, 2017 - 12:12 am:

George, you were correct to question the comment: "a wider gap gives a weaker spark. Narrower gap gives a hotter spark".

A wider spark plug gap requires a higher voltage to jump the wider gap than an narrower gap. That means the primary coil voltage has to rise to a higher value and that is accomplished by storing more energy in the coil's magnetic field when the points open, not less. The wider spark gap requires greater spark energy, not less.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Friday, February 10, 2017 - 07:49 am:

Exactly right, and we are in total agreement, as you are not saying anything other than what I said.

Given the same amount of spark energy, it is a narrower gap that will be more intense and thus less likely to foul, which is why Champion specified this .025" dimension for the Model T Ford.

A wider gap spreads the same amount of energy over a longer span of air space.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, February 10, 2017 - 09:25 am:

Royce, Exactly wrong, in total dis-agreement with what I stated. You can theorize all you want, you can rationalize all you want to justify your incorrect statement but it remains incorrect. So much of what you state as gospel fact is totally wrong, its really disturbing how many readers are lead astray by your erroneous posts that are NEVER acknowledged as wrong, or corrected. Please take the initiative to do at least some basic research before you post.


A wider gap requires MORE energy (A.K.A. Hotter Spark) in order to jump the wider gap. The break down voltage is much higher but the probability of failure to jump the gap (misfire) increases with gap width. A narrower gap requires less energy (Colder spark) and the probability of failure to jump the gap decreases but that alone Does Not guarantee a misfire is less likely to occur. The spark has less energy; therefore is less likely to initiate combustion (misfire) under adverse conditions (non-ideal mixture conditions, fouled electrodes, etc.). Which gap is less likely to foul, misfire, etc, for a particular SI engine application depends upon Many variables; spark plug gap being just one of those variables; there are many other spark plug variables to be considered as well as coil, dwell time, mixture, and combustion chamber variables. Champion specified a specific gap for their product based on a specific combination of all these variables.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Friday, February 10, 2017 - 09:52 am:

I would caution anyone to stay away from wire brushes to clean sparkplugs. At least when it comes to the porcelain. It may not be big deal on glazed porcelain, but if it is unglazed, metal from the brush will embed in the porcelain and create a conductive path back to ground. The current will follow that rather than jump the gap. Don't ask me how I know.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Todd, ............Red Deer, Alberta on Friday, February 10, 2017 - 11:12 am:

"Is there a way to clean out the cylinders without removing the head?"

Don't worry about the carbon in the cylinders, just regap your plugs to .032" or .035" and DRIVE it, but don't thrash it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Friday, February 10, 2017 - 11:13 am:

Ohms law states that when resistance increases (wider gap) total current flow goes down which in the case of an ignition system for a gasoline engine, a system which is rapidly switched on and off, results in a reduction in spark duration. Spark duration is analogous to spark quality.

While we might agree that a wider gap requires a higher voltage to create a spark, that does not mean that a wider gap forces more electrical energy through the coil primary. The energy induced in the coil is a function of the voltage available to the primary side and dwell.

Based on the above I'm with Royce on the question of plug gap. The model T combustion chamber is far from optimal. It needs more spark duration than peak secondary voltage.

However, I am here to learn and I remain open to other points of view as long as they are fact and data driven.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Todd, ............Red Deer, Alberta on Friday, February 10, 2017 - 11:32 am:

"Ohms law states that when resistance increases (wider gap) total current flow goes down"
That's true, as long as the voltage stay's the same, which in this case it doesn't.
There is a variety of factors involved.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Rogers - South of the Adirondacks on Friday, February 10, 2017 - 11:40 am:

Be careful when stating facts here on the forum.

I learned the hard way a while back when I posted a few facts and got my @ss handed to me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, February 10, 2017 - 03:42 pm:

Facts backed up by data and/or solid references are welcome. Here is a reference from NGK regarding spark plug gap: http://www.ngkntk.co.uk/index.php/technical-centre/spark-plugs/spark-plug-gap/

"A gap that is too small means that the spark duration will be very quick and the spark will be thin and weak. The consequences of this may be bad starting and high exhaust emission levels. This will result in an increase in fuel consumption. If the gap is set too large, the ignition system will not be able to cope with the demands and a misfire situation will occur". By not being able to cope, they mean the coil cannot store sufficient energy to produce a high enough voltage to jump the wider gap or voltage breakdown occurs else where internal to the coil or system before the electrons jump the intended spark plug gap.

Also see: http://www.ngkntk.co.uk/index.php/technical-centre/spark-plugs/fouling-range/

Regarding carbon fouling, they state: "Check for rich air/fuel mixture. Check the entire ignition system and cooling system (excessive cooling)." In agreement with others have suggested.



(Message edited by mkossor on February 10, 2017)


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration