Yes, hopefully this year I will have my engine back in my 412 and be able to test run this.
It is actually a mechanical spring contact switch just like the stock one...but is much more reliable. Here is what it entails:
(1) trigger point arms cut from small (3/16") square section torlon stock. Small light and stiff. Each trigger arm is .75" long with a fulcrum point in the dead center on a 1/16" steel pin.
The cam follower for each trigger arm is a torlon roller cut from rod stock. There is a strip of chromolly up the back and front of each (u-shaped) as a stiffener and the springs bear upon it.
(3) The fixed contact points are made of a slice of the same chromolly and anchored by a 1/16th pin
(4) The contacts themselves are made of gold plated silver rod (had a friend of mine make me about 20 of them. They are 1/8" in diameter
(5) The signal is carried by high temp silver plated copper wire...soldered to each contact and running down the back of each trigger arm. Very clean. I ahven't figured a way to crimp these on yet instead of soldering but I will.
(6) There are eight trigger arms in all. Four actual trigger arms and four interupter arms. You find two arms at approximately every 90 point...although there are still only two actual triggering cam points 180 degrees apart.
(7) each pair of triggers has a "hood" that stretches over them made of pourable cast silicone...that is high temp and super pliable. It effectively keeps all oil and grease from the contacts.
(8) The springs are made of simple bent spring steel. (bought it at Elliots hardware in Dallas a couple of years ago $6
). They have a single bend and are mounted on teh plate between two pins and go into a stot cut in each arm. They are slightly stiffer than the stock triggers
This plate must be installed from the top of the distributor because it wraps all around the cam and shaft...but its position can be adjusted through the original side plate opening....even while running.
The whole mess is roughly 17-19 mm thick. Just fits in the D-jet dizzy.
It uses essentially eight cams that are very flat and thin made of teflon or Peek 1/16th" plate. I originally thought that torlon would be killer...but at about $900 for a 6" x 6' x 1/4" thick plate....
...maybe too killer. I made four plates of each (PEEK and teflon)..just to see. It would be roughly $100 worth of PEEK for all four cams ...or $20 worth of teflon for all four cams. The PEK and Torlon are much stiffer, but all are so low in friction and so high in temp range....that no lube in this system will be reuired especially with a torlon cam folower on a teflon or PEEK cam.
A refresher: D-jet has only two injection driver channels. In order to energise one...the field from the other has have built and then collapsed. So...if one trigger is malfuntioning, you get no injections at all....as the other trigger will not enable until its opposite has cycled.
In operation.....each D-jet channel has a window of injection opportunity. As far as the ECU is concerned...this is not degree related...it is time related. If you look at the cam in the dizzy...it opens each set of points and keeps them open for very close to 180* of trigger cam/dizzy shaft rotation.
The most important part about that...is what the actual surface length is of that cam lobe. So...the trigger point cam follower/rubbing block...travels a specific length or circumference of that cam lobe.
That length of lobe relates to length of time....as multiplied by the speed of rotation......with me so far?
So...what I have done is using the same two injection channels I am firing all four injectors at one time at each of the two injection points....instead of in pairs.
Reminder.....it takes two complete 360 degree crank revolutions to bring all four cylinders through all four strokes. During that...being that the dizzy runs at 1/2 speed....it takes a full 360* turn to hit four firing points now (instead of two)
But....each injector has an interuptor cam (its actually distributed between the four interuptor cams at multiple points)...that only lets each injector fire at a specific 90* point.
This Stack of cams is mounted essentially a modified steel shaft collar split clamp on the dizzy shaft. In this way I can set up the start point of #1 injector to fire at the instant the intake valve on #1 begins to lift. With proper spacing...the other three fire at essentially 90* spacing (but 180 degree time intervals).
The eight cams were indexed together, properly spaced and pinned together.
The 8 cams are a total of .75" thick with 1/32" spacers between each.\
The whole gist is that the interupptor cams work by breaking the injector ground when they are not allowed to fire
What used to be pairs of injector grounds grounding at the block centerline was broken into four seperate injector grounds and pigtailed to the dizzy.
I noted the time factor and cam lobe length earlier. These cams are larger in diameter...so in effect....with the lobe face father from the vertex point....each degree of arc/rotation...happens in a slower time frame. This is how I was able to get two channels to effectively act like four.
The system still thinks its firing the same two channels (and it is)...at the same approximate injection window length. Its just that its been spread out and by interuption......its really only firing one injector at a time.
The risk is this.....In reality.....I am using roughly half of each original injection window of two channels...splitting it into four.
The same two injection channels are firing one after another. The worry is that they will have to cycle slightly faster...which may cut off some of teh potential open window time.
If teh ECU can then not cycle fast enough...I will make up teh difference in percentage of fuel lost (whcih will be linear across any rpm range)...with higher fuel pressure.
It works. I just need to see if its tunable.
I have not yet finished the centrifugal advance mechanism that would advance the injection point by twisting the trigger plate (just like points)...to advance the point of injection ..starting at about 1200-1500 rpm and ending at about 2200-2500 (specualtion at this point)....because after that it may not matter.
It really is very simple...its just hard to explain. Ray
