Initial timing, static timing, and centrifical advance

[claymore]

Again this DOES NOT apply to the FIT but is more of a nice to know type information post that applies to other Hondas with a distributor. In the Jazz Fit all these are controlled by the ECU.

This is NOT a DIY it's more of nice to know technical information. And this does NOT apply to your Jazz as it has no dizzy.


This is NOT a DIY but since distributors have so many LITTLE TINY parts and screws. You do any work on your distributor at your own risk. Honda Fit forums takes NO responsibility for any action taken by members in regard to this post.

Ok first things first... everyone has probably heard about "setting the timing" on cars ...just what the heck does that mean?

While I write this post about CARS in general they apply to most Hondas also. So please no pm or replies like "well what about my 1232DDF 1923 Humpmobile" there are so many different type of ignition systems I couldn't possibly cover them all in this short post. So for this post I will be explaining things in GENERAL terms not specifically one car or engine.

OK where were we.... Setting the timing. The first thing you have to understand is that fuels burn at different rates, which simply means one fuel takes less or more time to burn inside the combustion chamber than other fuels. Many things can effect how long fuel takes to burn but fresh fuel, at normal temperatures, the higher the octane the SLOWER it burns. Strange isn't it most people automatically think higher octane fuel has more power so it must burn real fast.

The reason the ignition timing needs to be adjusted is you have to start the spark from the plug soon enough or the flame will follow the fuel across the piston head never catching up with the fuel because the spark was started too late and a lot of the unburnt fuel goes out the exhaust valve loosing valuable power from the engine.

Just like a runner trying to catch a faster person if you (the slower person) gets a head start you can beat the faster guy. If you have too much timing the spark goes off igniting the fuel as the piston is STILL COMING UP and that is very bad for the pistons so you have to have some means to adjust the timing under all conditions.

YEA I know there is a guy jumping up and down in the back yelling what does this have to do with timing we will get there in a second you have to know WHY you have to adjust the timing before you can do it.

Here are some more terms you need to know before we get to timing. "TDC" I know some of you have been reading the manuals and saw this term and thought WTF?

TDC is very simple all it refers to is when the piston is at the very top of the bore not going up not going down ...easy. The abbreviation TDC is for the longer Top Dead Center.

Same thing the piston is not going up or down BUT remember the piston is going to the top TWICE for every ignition firing and at 7000 RPM it is MOVING VERY FAST. It's easy to know what TDC is but fairly complicated to find EXACTLY. It is an involved process if you are degreeing a cam where gauges and degree wheels are used but that is a subject for another post.

So what the heck do we normal guys have to do when setting our timing and the book said 10 degrees after TDC? Easy, in general again most car engines have TDC marked on the Crank pulley or harmonic balancer (believe it or not WAY back in the old days the FLYWHEEL had the timing marks) and the standard "Best setting" is normally marked on the crank pulley.

So here we are we know what TDC is and that fuels burn at different rates SO WHAT. The reason you have to adjust your timing is because that nasty old fuel takes TIME to burn. If the ignition fired every time at the same exact time from TDC at slow speeds it would have enough time to burn all the fuel BUT at high speed the fuel would only partially burn because there WASN'T ENOUGH TIME to burn all the fuel.

So what do we have to do to get the right amount of time for the fuel to burn under MOST conditions? Fortunately the car builders have taken care of that for you. They have done all kinds of testing and found out the best amount of time needed to burn almost all that fuel under MOST running conditions. And that is where setting your timing comes in.

What you are doing when you break out the timing light and turn the distributor is adjusting the STATIC TIMING from TDC to factory specs. . OK what the heck is static timing? All static timing stands for is a STARTING point with the engine STOPPED (static means stopped or not moving). If your an old timer like me you CAN set the static timing with the engine off but most people use the handy timing light. Now that your learning about Static timing you have to know that static timing is ALSO called INITIAL TIMING because when you set the timing you are setting ONLY the initial timing point because guess what there are MORE types of timing besides static.

WHEW now we have to talk about more timing.... for this post we will stick to calling it Static timing. so now that we started to adjust the static timing (we will get back to "Setting the timing later").

OK we got the initial timing set and we have to go from that point. Initial timing means that the engine will run OK right around idle and slower speeds but how the heck does the engine get the right ignition timing at higher speeds I can't jump out of the car run along side and turn the distributor?

In the REAL OLD days cars came with a mechanical lever mounted on the steering column that was hooked up to the distributor and physically turned it to adjust the timing but most of us have more modern cars so we will skip that SORT OF...

If you have an older one of the Hondas you may even have a mini flying saucer on it's side connected to your dizzy with a rubber hose leading out of it hooked up to the intake manifold that you may know is your vacuum advance. Since the car makers knew most people didn't know how to use the lever to adjust their timing so they had to think up a new invention to turn the dizzy. Some engineer though about engine vacuum and how the heck that could help. Some brilliant nerd came up with the idea of connecting a movable plate inside the dizzy so you didn't have to turn the whole dizzy only this inner plate.

http://img.villagephotos.com/p/2005-12/1118998/Dizzy2.jpg
Photo by ECU-Man

In this photo, that I got thanks to ECU-MAN, is a modern dizzy looking at the inside after taking the rotor off. Since this is the only photo I had you have to imagine the flying saucer off to the left with an arm connected inside the dizzy to a plate like the one here showing all the modern ignition parts shown here. The part marked "grab this" has a bump on the post down where the arrow like a "C" is. In the old days that is where the points and condenser were and the bumpy part had more bumps on it and that would open and close the points controlling the timing.

So what does the vacuum advance enclosed diaphragm do for our timing? Most internal combustion engines have High vacuum at closed throttle settings so to give our engine a shot of advance to get the car rolling off idle and low speeds the high vacuum from the engine is routed from the intake manifold through a hose into the vacuum advance. This vacuum on the engine side of the diaphragm pulls on the rubber diaphragm which pulls on the metal arm connected to the inside of the diaphragm which is connected to the ignition plate. The plate then rotates in the opposite direction to the rotor turning. When this turning happens you are ADVANCING (giving more timing) the timing for the engine.

If you have vacuum advance on your dizzy you can see this all work. It you haven't yet take off your dizzy cap and the rotor and locate the ignition parts plate. Then just disconnect the hose at the intake manifold CLEAN it off and suck on it like a soda straw. When you do that the ignition parts plate SHOULD move. Put your tongue over the hole like you did as a kid with a soda straw and the vacuum advance canister should hold vacuum then take your tongue off and the plate should move back to it's original position. YUCK!!

So the vacuum advance gives a shot of timing to the engine just off idle but what happens as the speed of the engine increases? As you may have figured out as the throttle is opened to increase engine speed the vacuum falls so there is less vacuum pulling on the diaphragm so the diaphragm moves back to it's rest position and that moves the arm which then moves the ignition plate back to it's non-advanced position.

This post is too long so I have to make it a two parter Back in a second.

[claymore]

Back again...


So what the heck how do we get the advance the engine needs as the Rpm goes up? Well the simple answer is there is YET ANOTHER type of ignition advance the CENTRIFICAL ADVANCE.

Everyone should remember from your childhood the game where you spin around slowly then increase your spinning speed and your arms raise up more and more as your spinning speed increases. Well under your ignition parts plate inside the dizzy there are a set of arms that move in and out depending on the engine speed. the arms are controlled by a set of springs that determine how fast and how far out they move.

As the inside of the dizzy is all cluttered up with parts and the ignition parts plate is being controlled by the vacuum advance where the heck does the centrifical advance arms connect to? The arms are connected to the center post that holds the rotor and you can check to see if you have centrifical advance easily.

http://img.villagephotos.com/p/2005-12/1118998/Dizzy2.jpg


If you look in the photo you can see the rotor stub just grab the stub and try to carefully turn it clockwise or counterclockwise and if you have centrifical advance the stub will turn and you can feel the tension from the springs, and it moves back on it's own when you let go.

When the engine speed increases the arms move outward and being connected to the rotor stub the rotor hub also moves increasing the timing more and more as they move outward.

So are we done with all the different type of timing and advance.... NOT YET one more to go. The last one is probably the most important one to all performance oriented members TOTAL ADVANCE. All that means is all the other forms of advance COMBINED.

The reason total advance is important is because this is the one that MOSTLY determines if the engine will run at it's peak performance or it is TOO MUCH advance and the engine will PING and eat your pistons.

If you have them vacuum, and centrifical advance can be adjusted and you can set the static or initial timing. You can do it the hard DIY way by replacing washers on the vacuum advance can or changing the springs on the centrifical advance arms to ones harder or softer and step by step check the changes one by one with your trusty old timing light so the total advance you are looking for is obtained. Or you can do it the easy way.... distributor shops that repair dizzys have a MACHINE that they put just your dizzy into and it will tell the repair man how much of each advance you are getting from your dizzy and then he can make instant changes by changing the springs or washers right on the machine and try it again without having to put the dizzy in and out of the engine much easier than DIY.

Now that we all know everything about timing now we can cover setting the initial timing on your car. What you need is simple, one timing light, one piece of chalk or white paint, and the repair manual or timing specs. for your particular car.

The mysterious "timing light" is not mysterious at all it's real easy. All that a timing light is is a disco strobe light it "stops" the crank pulley so you can see where the timing lights line up.

So we start by parking your car in a spot where it can be run and the exhaust won't build up and kill you or your family inside the house. Make sure the car is in NEUTRAL, parking brake on, engine warmed up to operating temperature,idle at normal operating Rpm, the rest of your electrical system should be shut off like lights, radio, A/C etc. In some cases you have to locate a shorting plug in the engine compartment and short it. If you have vacuum advance disconnect the vacuum hose and plug the opening with a screw or bolt.

http://img.villagephotos.com/p/2005-12/1118998/Dizzy1.jpg

You need to loosen the bolts holding your dizzy to the block and in this photo from the ECU-MAN collection the UPPER red arrow points to one of the bolts (ignore the other arrows). There are normally two more bolts holding the dizzy to the block of the same type that are below the dizzy cap. Loosen these bolts just enough that the dizzy can be turned but the dizzy is not loose enough to wobble around.

Then you need to look down toward the bottom of the engine and locate a pointer of some type usually mounted on the engine timing belt cover and mark the tip of it with the chalk. Then look at your crank pulley and there should be lines or marks on it sometimes with writing with TDC or BTDC and then the correct initial timing mark usually 10 degrees or so further on. Mark these lines or marks with the chalk.

Most timing light come with clip on wires that are red and black or marked positive and negative that need to be clipped onto your battery with the correct positive and negative connections.

The last thing is the other wire coming from the timing light. Most modern timing lights have a spring connector that just clamps over your number one spark plug wire and you are ready, but some of the older ones just have an alligator type clamp so what you need to do is get a paper clip and straighten it out and carefully so you don't rip the rubber boot slide the paper clip between the boot alongside that wire and push it down so it is touching the metal end of you number one spark plug lead and we are ready to go.

Once everything is hooked up start the car and point the timing light down into the engine so it is shining on the timing pointer and the crank pulley and you should see that the timing marks you chalked up should be clearly marked.

Then all you have to do to adjust your initial timing is SLOWLY turn the dizzy and the pointer and the marks should move closer to being lined up or farther away just turn the dizzy the correct way so the timing mark and the pointer are lined up. Then carefully tighten the upper bolt holding the dizzy so you can't move it and make sure the marks are still lined up if they are shut off the engine tighten the rest of the bolts, disconnect the timing light IT'S MILLER TIME DONE!!

If you are good with math and measuring you could approximate the amount of total advance you have. Measure from TDC to the 10 degree mark WITH THE ENGINE OFF and note how many mm it is then just mark the crank pulley the same amount of mm further around the pulley until you get to about 40 degrees or three extra marks. Then just start the engine and have someone race the engine and you will see how much further the mark moves toward to 20, 30 or 40 degree marks you just made.

Now that we learned all that guess what soon it's all going to be worthless. The most recent cars have the timing controlled by the ECU so about the only thing you can set is the initial timing and even that is GONE like on the JAZZ no more DIZZY every timing change is made by the ECU so the need to learn how to use a timing light is going bye bye and you better brush up on your computer skills because that is the future way of adjusting your timing. BOOOOOO