Modified my trigger wheel today
12-07-04, 05:51 PM
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Hamado things my way!
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Modified my trigger wheel today
I modified my trigger wheel today. I was sick of not being able to just hook up a timing light, and make sure my ECU was doing what it was supposed to. I followed the instructions on Paul Yaw's website: http://www.yawpower.com/pultime.html
I measured my trigger wheel (make sure to be in the center, if you go to one side or the other, it will mess everything up), and it was 5.0395" in diameter. So to be 5 degrees apart, the marks should be .219778" apart. I would recommend measuring your wheel first, incase they aren't all the same size (or my caliper was fucked up), but going from the stock timing mark (20* ATDC) my measurements went like this:
15*ATDC=.2198 / 10*ATDC=.4395 / 5*ATDC=.6593 / TDC=.8791 / 5*BTDC=1.0988 / 10*BTDC=1.3186 / 15*BTDC=1.5384 / 20*BTDC=1.7582 / 25*BTDC=1.9780 / 30*BTDC=2.1977
In my pictures, the white marks are on 20*ATDC, TDC, and 15*BTDC. The gold mark is at 5*ATDC (for idle). All the other marks are a metallic purple. The car is in pieces at the moment, but I'll see how it works.
Any questions or comments are welcome.
You don't have to buy an expensive aftermarket pulley just to have the appropriate timing marks. It is quite simple to make additional marks on the stock pulley.
The first step is to remove the stock pulley. This comes off easily by removing the four 10mm. screws that hold it in place. Some of the stock pulleys are indexed, and will only go on one way. Others can be placed in any of four positions, (90 degrees apart.) so I recommend spinning the engine to top dead center before removing the pulley so that you don't put it on wrong.
You will need a pair of vernier calipers, a small file or hack saw blade, a roll of masking tape, a calculator, and some brightly colored paint. If you do not own a pair of calipers, this is just the excuse you need to buy a set. Most retail tool supply stores carry them. They range in price from $25 to over $200. Luckily, the $25 calipers are more than accurate enough for this application, and once you have a set, you will be amazed at how often you use them.
Do not buy a set of plastic calipers from Sears or Home Depot. These are absolute crap, and most of them are colored to look like stainless steel so you will buy them, only to find that they are pieces of **** once you get them out of the package. A good set will have a small dial gauge, and come in a protective plastic box. Note: Amtos is a good inexpensive brand.
Step by Step
1. Measure the diameter (Distance across.) of the pulley. This should be approximately 4.5 inches.
2. Take the diameter, and multiply it by 3.14. This will give you the circumference (Distance around.) of the pulley
3. A full circle is divided into 360 degrees, so if you divide the circumference by 360, the answer will be the distance around that equals one degree. For this application, 5 degree increments will be fine, so divide the circumference by 72. The answer will be the distance around the pulley that is equal to 5 degrees.
Example: If the pulley is 4.5" in diamter, 4.5 times 3.14=14.13. 14.13 divided by 72=.196. so .196 = 5 degrees.
4. Tear off a piece of making tape approximately 3 inches long, and stick it to a smooth flat surface. Make a mark at the far left side on the edge nearest you, and label it TDC, for top dead center. Using your shiny new calipers, set them at 5 degrees, which using the above example is .196 inches. Make a mark .196 inches to the right of the TDC mark. This is your 5 degree mark. Now multiply .196 by two (.393). Set your calipers to this number, and make another mark .393 inches to the right of the top dead center mark. This is your 10 degree mark. Now simply continue to multiply the 5 degree number by 3,4,5, and 6 to get your 15, 20, 25, and 30 degree marks.
You are probably thinking screw that, I'll just set the calipers at .196 (5 degrees) and measure from my last mark. Doing it that way will multiply your errors as you get further from TDC. If for instance your mark is off by .005", and you make the same error every time, by the time you get to 30 degrees, you could be off by several degrees! Take your time and make it accurate!!!
5. Stick the tape to the pulley lining up your TDC mark exactly with the TDC mark on the pulley. Looking at the pulley from the front, with TDC on top, your tape marks should be to the right of TDC, and the factory 20 degrees after TDC mark (Trailing.) should be to the left.
6. Now take a small square, or triangular file and make a notch on the pulley at each of your marks. Make sure that your notch is exactly centered on your pencil mark.
7. Dab some brightly colored paint into each of the notches. If you are using a spray can, you can spray the notches, and wipe off the excess with some solvent and a rag. If you lightly wipe the excess, the paint will remain in the low spots that you filed into the pulley.
8. Put the pulley back on the engine and you are done.
The first step is to remove the stock pulley. This comes off easily by removing the four 10mm. screws that hold it in place. Some of the stock pulleys are indexed, and will only go on one way. Others can be placed in any of four positions, (90 degrees apart.) so I recommend spinning the engine to top dead center before removing the pulley so that you don't put it on wrong.
You will need a pair of vernier calipers, a small file or hack saw blade, a roll of masking tape, a calculator, and some brightly colored paint. If you do not own a pair of calipers, this is just the excuse you need to buy a set. Most retail tool supply stores carry them. They range in price from $25 to over $200. Luckily, the $25 calipers are more than accurate enough for this application, and once you have a set, you will be amazed at how often you use them.
Do not buy a set of plastic calipers from Sears or Home Depot. These are absolute crap, and most of them are colored to look like stainless steel so you will buy them, only to find that they are pieces of **** once you get them out of the package. A good set will have a small dial gauge, and come in a protective plastic box. Note: Amtos is a good inexpensive brand.
Step by Step
1. Measure the diameter (Distance across.) of the pulley. This should be approximately 4.5 inches.
2. Take the diameter, and multiply it by 3.14. This will give you the circumference (Distance around.) of the pulley
3. A full circle is divided into 360 degrees, so if you divide the circumference by 360, the answer will be the distance around that equals one degree. For this application, 5 degree increments will be fine, so divide the circumference by 72. The answer will be the distance around the pulley that is equal to 5 degrees.
Example: If the pulley is 4.5" in diamter, 4.5 times 3.14=14.13. 14.13 divided by 72=.196. so .196 = 5 degrees.
4. Tear off a piece of making tape approximately 3 inches long, and stick it to a smooth flat surface. Make a mark at the far left side on the edge nearest you, and label it TDC, for top dead center. Using your shiny new calipers, set them at 5 degrees, which using the above example is .196 inches. Make a mark .196 inches to the right of the TDC mark. This is your 5 degree mark. Now multiply .196 by two (.393). Set your calipers to this number, and make another mark .393 inches to the right of the top dead center mark. This is your 10 degree mark. Now simply continue to multiply the 5 degree number by 3,4,5, and 6 to get your 15, 20, 25, and 30 degree marks.
You are probably thinking screw that, I'll just set the calipers at .196 (5 degrees) and measure from my last mark. Doing it that way will multiply your errors as you get further from TDC. If for instance your mark is off by .005", and you make the same error every time, by the time you get to 30 degrees, you could be off by several degrees! Take your time and make it accurate!!!
5. Stick the tape to the pulley lining up your TDC mark exactly with the TDC mark on the pulley. Looking at the pulley from the front, with TDC on top, your tape marks should be to the right of TDC, and the factory 20 degrees after TDC mark (Trailing.) should be to the left.
6. Now take a small square, or triangular file and make a notch on the pulley at each of your marks. Make sure that your notch is exactly centered on your pencil mark.
7. Dab some brightly colored paint into each of the notches. If you are using a spray can, you can spray the notches, and wipe off the excess with some solvent and a rag. If you lightly wipe the excess, the paint will remain in the low spots that you filed into the pulley.
8. Put the pulley back on the engine and you are done.
15*ATDC=.2198 / 10*ATDC=.4395 / 5*ATDC=.6593 / TDC=.8791 / 5*BTDC=1.0988 / 10*BTDC=1.3186 / 15*BTDC=1.5384 / 20*BTDC=1.7582 / 25*BTDC=1.9780 / 30*BTDC=2.1977
In my pictures, the white marks are on 20*ATDC, TDC, and 15*BTDC. The gold mark is at 5*ATDC (for idle). All the other marks are a metallic purple. The car is in pieces at the moment, but I'll see how it works.
Any questions or comments are welcome.
12-07-04, 06:49 PM
#3
Hamado things my way!
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It may be a little off balance, but I seriously doubt it will have any effect. I mean, if you look at an unmodified pulley, it has a big tab poking out one end, and a big notch at about 120 degrees away. I can't imagine the little amount of material I removed having any ill effects on the car.
12-07-04, 07:11 PM
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Hamado things my way!
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I honestly don't know. I've been running around 14* advance at 10-12psi on stock nonsequential turbos, but now that I'm putting a single on, I want to be sure that **** is exact.
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