I am trying to finish a microsquirt conversion on a vw aircooled engine by this weekend.
I am using a 36-1 and I didn't think about it before I drilled and tapped the aluminum pulley wheel. I am stuck when I try to figure out the offset angle. See pic below, Top Dead Center is at 12-o clock the missing tooth is at 4-o-clock and my sensor location is at 6-o-clock
As I understand, my missing tooth is 10 teeth before TDC, my sensor is 8 teeth before the missing tooth I was thinking that means 80 degrees???
cnicholls wrote:As I understand, my missing tooth is 10 teeth before TDC, my sensor is 8 teeth before the missing tooth I was thinking that means 80 degrees??
You are mixing up concepts. "my missing tooth is 10 teeth before TDC" has no meaning.
Set the engine to TDC. Now look at the angle between the sensor and tooth#1.
I'm not trying to be difficult I am just trying to understand. I drew it out below, I am uncertain if I count clockwise or counter clock wise. The 2 option are below one in Black ink is it 70° or in Red Ink is 280°
or I may be all wrong. I just want someone to double check me.
I think your "tooth #1 angle" is about 280 deg. However don't make this too complicated. Enter any guess you want for that angle, then check timing by cranking with spark and fuel disabled. See what you get with the timing light, then change that tooth angle and see if timing gets closer or further from what it is supposed to be. Based on that you will know which way to be changing tooth angle, and will quickly get a hint on how much. With just a few iterations of this process you can get the tooth angle right on. Use a simple (non dial-back) light, and you may have to add some temporary marks on the crank if you can't see the one at TDC with your first tooth guess; or simply try a few other guesses until TDC is visible with the light, even if way off. After the engine is running you will want to check timing again, of course, and check it all the way through the expected rpm range to see if it "drifts" with rpm.
I posted this on a different thread and this my help you think thru the process.
Hope this helps
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This is how I do that trigger angle stuff on a full sequential install. Lets assume you have either a missing tooth wheel or a even toothed wheel on the crank or cam. Lets also assume you have a cam trigger wheel with one tooth. Let's assume you have no clue where any of the teeth are located in the 720 degrees of crank rotation.
1) Remove the fuse from the injectors. The last thing you want at this point is the motor trying to fire and mess up the flywheel ring gear.
2) Connect a cheep timing light with no timing offset knob.
3) Set the code to fixed timing at 0 degrees.
4) Locate and verify the 0 degrees timing mark on the harmonic balancer.
5) Set the tooth one timing offset to zero degrees.
6) I like to paint a really clear zero timing mark with black permanent marker on a white paint background on the front of the harmonic balancer that is really easy to see and a pointer
7) Have a friend crank the motor and look where the mark is compared to your pointer. Change the tooth one offset by adding say 45 degrees and retest. Within about 6 tries, you will find that the spark is real close to your 0 timing mark. The only catch is you will have no clue if you are off by 360 degrees of crank rotation. Never go over 360 degrees on this setting at this point in the process.
8 ) Now set the timing to 15 degrees, power up the coils and try starting the motor. If it fires you won the 50 - 50 chance and you got lucky.
8a) If it does not start, add 360 degrees to the timing offset and the motor will normally fire right up.
9) Assuming you have a 15 degrees timing mark on the harmonic ballancer, dial in the timing offset the last few degrees to dial it dead on with the motor running.
10) Rev the motor a few times and make sure the timing is not moving from 15 degrees. If it does, you will need to mess with the timing hysteresis to get things stable as rpm changes.
11) Turn the normal timing back on and move on to fueling.
Pay close attention to the logs looking for Lost Sync Errors. Any errors wile the motor is running are a big problem. This is when you need to get into taking composite trigger logs. Matt at DIY is really good at looking at those and helping out.
It takes about 10 min and math is not involved. That's how I do it...
