How Do You Change Spark Plugs?

[Zanzer]

^^ That's what I was thinking too. I have a TON of decent plugs I've pulled from other motors. I thought about doing a set for a tank or 2 just for giggles


When people want me to build them something I like using the old Mad Max quote: "Speed is just a question of money. How fast do you wanna go?" :mrgreen:

And one of my all time favorites from Two Lane Blacktop: "How fast does it go?" - "Depends who's watching"

[htchbck]

Also like the quote from Tokyo Drift (yes I know its a retarded movie, but cool looking cars and girls in it lol) that pretty much describes the mindset of many of the dumb kids that go watch that movie (I said many not all). When the football jock gets done rattling off all the "specs" of his (dad's) Viper, and the main guy just looks at him and says "Wow, I'm impressed... you can read a brochure." Sorry, didn't mean to hijack this into a quote thread.

Back on topic, I always use Autolites with antiseize and a torque wrench on a cooled down B3 engine. Other than that, doesn't really matter on a festiva. You can pull all the plugs at once, then put them all back in at once, which I usually do to ensure that I only have to change the clockwise/counterclockwise setting on the wrench twice (at most, if it was in clockwise to start with). I guess I'm lazy... that or the reversing lever on my wrench gets stuck a lot so its a pain in the butt. With the Autolite 64s I used to gap them, but after three or four sets were all within spec out of the box I stopped messing with that lol. And once all the plugs are back in, if you can't tell which wires go to which plugs by their length then you probably shouldn't have tried to do the plugs yourself in the first place

[Zanzer]

^^ HAHA! Forgot about that quote! Love it!

Another tip for plug wires for those who fear they may mix up the order. You can number the wires with a white paint pen or get really fancy and use a label maker or the little stickers that are pre-printed

[htchbck]

white paint pen or get really fancy and use a label maker or the little stickers that are pre-printed

I think you meant to say use white-out (most of us are poor here lol). I always have that and a black sharpie in my toolbox, pretty much any clean surface under the hood can be marked by one or the other of those two

[Zanzer]

Same here. I have a Sharpie and a little bottle of white touch-up paint. 2 of my most used tools

[WmWatt]

I forgot the tip someone posted here a while ago of sticking a length of tubing on the end of the sparkplug to use as a handle to get it started in the hole. I use a 3" extension between the sparkplug socket and the ratchet and just pull it off the ratchet to use as a handle to start turning the spark plug in it's hole.

[JohnGunn]

Best advice I can give... take out any pieces of tubing first and make sure the spark plugs aren't small enough to fall into the cylinder.

^^X2

Beat me to it. Damn.

[newfestiva]

Because I'm frugal I think changing spark plugs is a great time to mentally calculate how much money I've saved by owning a Festiva. Of course I have a little book in the glove box detailing every expense since the car was new to me. (in this case 2 weeks) and then comparing it to other cars that I've owned. How much per mile has the car cost me? How much per month. My wife's car (09 Escape Hybrid) is costing around $700 per month. My Festiva has only cost $550 so far including purchase price. Every month that it runs it gets cheaper!

Just this afternoon I was talking to my wife about the cost of oil. Think about it... if a B3 engine costs $100 at a junk yard and then maybe $200 in new parts you have a $300 engine. An oil change costs around $20 thus after 15 oil changes you have bought a used engine. So here's the deal... spend $300 on a used engine and never maintain it. Will it run long enough for you to save $300 in maintenance expenses before it just stops altogether so that you can just go buy another one?

Of course, I could never just not maintain an engine but... it''s tempting. Just something to think about while changing your plugs.

[JohnGunn]

I've found many interesting comments in this thread. Some have led me to reevaluate many of my past beliefs and bring them into serious doubt. So much so that I have begun to think of some aspects of this pretty routine operation in new light. As a result I've decided to hold off on my plug installation for a while as I rethink some of my past misconceptions.

At the moment I'm thinking about spark plug gaps. Even though I knew the gap range recommended by Ford was .039" to .043", all manufacturers of the plugs listed for use in Festivas/Aspires listed the gap of those plugs as .044", without any exception that I am aware of. I thought all those manufacturers couldn't be wrong. I thought Ford must have changed the specs the way they changed the torque values for spark plug installation. So ever since I bought my first Festiva in 1994 I have been setting my plugs to .044". When Zanzer mentioned he set his plugs for the lower end of the range so they would stay in spec longer, it stunned me, and forced me to think about what was going on.

First, I'm not giving any kind of lesson here. I'm just saying what makes sense to me. So, if you find anything I say to be out of line, please correct me. I was mistaken for 16 years in the gap for my Festiva. I'd like to stop being wrong for want of clear thinking.

So the first question is, what does it mean when Denso and NGK and even Motorcraft lists the gap of the plugs for our cars as .044"? Here are my thoughts. These manufacturers design their plugs to be used in lots of different models and makes of automobile. That number represents the gap that the plug was designed around. the perfect gap for the dimensions of the plug. For example the ground electrode goes up from the body of the plug and makes a turn to go over the positive electrode. I would say the designers designed the length of the positive electrode and the length and placement of the bend of the ground electrode in such a way that when the ground electrode is exactly perpendicular to the top of the positive electrode the gap will be .044". They chose that as the ideal gap for the geometry of the plug.

What does that mean? Should we favor that number because the surfaces of the electrodes are perfectly parallel at that gap? I think I might. Here's why. When the surfaces are perfectly parallel the erosion over time will be retarded. Because you have a greater surface area that is closer to the surface of the opposing electrode. Stop to think of what happens when you set the minimum gap of .039". You will have to bend the tip of the ground electrode down closer to the positive electrode, but not closer at the center but closer to the edge of the positive electrode. So that when the two electrodes begin to erode they have only a small amount of metal to use before the gap starts to widen.

Perhaps a better way to explain what I'm trying to say is to talk about what happens when erosion takes place. The current will find the shortest distance between the two electrodes to jump. And as long as that spot is the shortest distance it will continue to jump across at that point. But because it jumps there all the time it will erode there and soon no longer be the shortest distance. Then the spark will jump at a slightly different point. If the electrodes are perfectly parallel the next closest distance might be anywhere directly over the positive electrode. That will not be the case in the bent down ground electrode. Only the part that is bent down closer to the positive electrode will be the next closest. Also, that bent down electrode is close to the edge of the positive electrode, so the amount of metal there is much reduced as well. As a result it will take a lot less time for the gap of this adjusted plug to enlarge.

I'll stop here. This is not easy to put into words so I'll wait and see if anyone can make sense of what I'm saying and respond to comments about what I've written in hopes of being able to explain myself better.

There is one last thought about gaps that I'd like to run by you all.

When I read a spec for a part that lists a range of values I normally think that the correct setting for that part is any value within that specified range. But in the case of spark plug gaps I think that understanding may be incorrect. Here's why.

I just looked at the Aspire Maintenance Schedule that came with the car when it was new in 1994. It includes a change of spark plugs every 30,000 miles. There are no entries asking that spark plugs be checked and regapped. That tells me that the spec of .039" to .043" is just the spec for the initial setting of the plugs. The designers of the engine certainly are aware that gaps will erode considerably in 30,000 miles. (I did a calculation of the amount of erosion in that many miles and came up with a range of between .018" and .028".) What that suggests to me is that the designers knew the amount of erosion and chose the initial values so that at 30,000 miles they would still be within acceptable running specifications.

If this makes sense, that would mean that stock copper spark plugs on a stock B3 engine will be within acceptable specification from .039" all the way up to (.043" + .028" =) .071". If my assumptions are correct, this gives a whole new meaning to the .039" to .043" range I have read so many times.

[denguy]

I bought my 92 F used in 95 with 50k miles. I wanted to put everything new on the motor. When I got to the plugs the first 3 came out easy. The last one snapped off at the head as soon as I put the wrench on it. The plug [autolite] had rusted almost all the way through just above the threads. What was left was fused into the head. It looked like something [water?] had laid in the pocket around the plug and corroded everything together. I tried everything and ended up taking the head off and picking out the plug thread piece by piece.
The funny part was that the electrodes, gap, etc. were in good shape on the old plugs. "No good deed..............."

[Damkid]

Forgive me for not thoroughly reading this thread, just the title alone makes me want to :banghead:

[anomoly40]

In my way of thinking, time is money. I make $26 an hour at my job. If a process such as changing spark plugs takes longer than half an hour, it would be cheaper paying someone else to do it. So I get the plugs, gap em, slap em in. Im not driving a race car. Same goes with changing the oil, distributor cap etc.

[TominMO]

In my way of thinking, time is money. I make $26 an hour at my job. If a process such as changing spark plugs takes longer than half an hour, it would be cheaper paying someone else to do it. So I get the plugs, gap em, slap em in. Im not driving a race car. Same goes with changing the oil, distributor cap etc.

But whoever you pay will not take the time to do the little things, like putting anti-seize on the threads or indexing them (if you care about that). Because time is money for the mechanic too.

[Damkid]

I've never even taken the plugs out of my V6 to even check them, it runs good so why would I write a long novel and start getting into the "Zen" on something as simple as changing spark plugs

K.I.S.S. - keep it simple stupid

[Safety Guy]

Chris wrote:

"Forgive me for not thoroughly reading this thread, just the title alone makes me want to..."

Ha! You built a FWD V6 Festiva. You can be forgiven your impatience.

Anomaly wrote:

"In my way of thinking, time is money..."

I agree. Since I only make $16.07 an hour I can occasionally be persuaded to delve into the details of something as mundane as changing plugs. As for this thread, I think it's great.

However, if John starts another one on "how do you fill your car up with gasoline?" then I'll probably skip it.

To each his own!

Karl