Well, I have been having fun with the great firewall of China today. For some reason it would let me access all of the Registry web site with the exception of the talk forum. So I turned on "browse in private" and wala, I was in. Possibly "browse in private" does not tell the server where you are, and our webmaster has received "specific and verifiable information about a threat" from China.
In any event Nigel has made a lot of progress with the trigger sensor bracket and the final assembly of the crank pulley, V drive mount and sensor. First step was to design and make the sensor clamp, followed by test fitting.
- First step in making the sensor clamp was a CAD drawing and then water cutting blanks from 25 mm aluminum. Partial machining has been completed in this photo.
- Sensor bracket blanks 2.jpg (34.22 KiB) Viewed 5209 times
- The blanks are then placed on a rotary table for milling.
- Sensor clamp installed with sensor retracted to check clearance for belt changes - Looks good! Belt slips easily past the withdrawn sensor and up between the crank pulley and V drive mount plate.
- Sensor bracket - belt removal.jpg (35.14 KiB) Viewed 5209 times
- Now check for running belt clearance. OOPS - does not clear. Need to mill material from the clamp body - which was planned anyway.
- Sensor bracket - belt clearance.jpg (34.76 KiB) Viewed 5209 times
So back to the mill to refine the top of the sensor clamp.
- Sensor clamp with nice half round profile milled on top to allow for running belt clearance.
- Reinstalled and belt clears nicely in all directions.
- Side view showing sensor in place and belt clearance.
Now we had to think about how to get the sensor positioned "on the leading edge of the 11th tooth from TDC" as recommended in the Electromotive set up manual. We are using the Electromotive ECU that can be programed with a laptop so we can have a custom advance curve. Based on Electromotive's recommendations we needed to use the 1/2" diameter round sensor, with its center positioned at the edge of the 11th tooth. Simple solution was a 1/2 inch diameter pointed dowel.
- Positioning tool in sensor clamp in place of sensor for set up.
- Sensor bracket set up tool.jpg (35.56 KiB) Viewed 5209 times
- Close up of the point on the positioning tool. Makes it easy to position the sensor. The sensor clamp is held to the V drive mount plate with bolts in slots that allow the clamp to be moved a total of 6 degrees, or 1 tooth on the trigger wheel.
- Sensor bracket set up tool detail.jpg (32.65 KiB) Viewed 5209 times
- To assist with sensor set up there is a small window in the V drive mount plate so you can see exactly where the setup tool is positioned on the trigger wheel. May need a mirror when installed to set it up, but it will work.
Once set, the sensor should not need readjustment. If a fan belt needs to be changed, you simply loosen an allen bolt in the clamp body, slide the sensor back out of the way and change the belt. When the belt change is complete you use a feeler gauge to set the sensor to trigger wheel clearance before tightening the sensor clamp. Should be pretty reliable.
Speaking of reliability, we have already mounted the V drive on a running motor to check for vibrations, harmonic or otherwise and found none. Later this month Ralfy will have a test motor down in LA for dyno tuning of the crank fire set up. The motor is built on a 912 case with LN 90 mm P&C for 1883 cc displacement. Twin plugged with 10.0/1 compression. The owner wants to run 48 IDA Webbers on tall manifolds (which should look pretty good with the 4 cam shroud) so the dyno tests will focus on the advance curve, carb jetting/venturis, and cam advance/retard.
The next post should have some better photos of all the final components. Thanks for following along!