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 Posted: Sat Apr 14, 2012 10:06 am Post subject: Notes on installing the Direct Fire Ignition |
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First, I've always been a fan of electronic ignitions. I looked into DIS a LOOOOONG time ago. So, when the time came to install not one, but two, DIS systems, I was kind of anxious to get started. Especially since one was a Real Tiger and the other was an AG Tiger.
How long does it take: Realistically, 16-20 hours.
Why? you ask? I probably spent at least 4 hours on each plane just looking for a place to put all the pieces and trial fitting everything before I drilled any holes.
1) Magneto Timing Housing: It replaces the right mag. That part was pretty easy.
However . . . The lead (wire connection) on the MTH is about a mile long (18 inches?) and I needed to find a place
somewhere above the accumulation of oil and dirt to mount it.
Then, of course, the wiring harness from the Controller is really long for a Grumman and I wanted it
to be where someone could R&R the MTH if necessary. So the connector had to be accessible.
Note: Best Case. It would be a whole lot better to have the connector right on the MTH housing.
Worst Case. Limit length of the lead on the MTH to less than 6 inches.
2) Coil: Where to put the coil? Here, there is a difference between the two planes.
AA5B: On the AA5B, the coil can go to the left of center on the firewall near the top.
I put it so that the #1 and #3 coil towers straddled the Carb heat cable.
AG5B: There are a lot of wires in the middle on the AG.
I put the coil under the wires toward the right side of the panel.
3) Controller: The installation of the controller and the MAP sensor are also different
AA5B: On the AA5B, the controller can go above the copilots right peddle on the firewall near the top and just under the "U" channel.
I used sheet metal screws into the firewall. The unit is light and the screws worked great.
AG5B: There are a lot of wires all over the back of the firewall on the AG.
There is literally no free space without moving something.
I moved the brake line on the left of center just above the cabin heat box.
I had to trim off the bottom edge to keep the controller low enough to stay away from the controls.
3) MAP sensor: The installation of the controller and the MAP sensor are also different
AA5B: On the AA5B, the MAP sensor can go adjacent to the controller (to the inside) above the copilots right
peddle on the firewall near the top and just under the "U" channel.
I used sheet metal screws into the firewall. The unit is light and the screws worked great.
AG5B: Same problem here. Too many wires everywhere.
I installed the MAP sensor about 6 inches to the right of the controller above the cabin heat box.
Note: The MAP sensor had a rubber hose coming out of it.
Weird if you ask me. A metal hose fitting would eliminate one potential leak.
4) Harness: The harness is just a bunch of loose wires. There is nothing professional looking about it.
On the AG, I was able to use 1/2 inch expando sleeve and get it over the VERY LARGE connectors.
Having the wires in a flexible sleeve help during the installation.
Note (1): The B+ lead from the coil goes from the coil to the 10 amp breaker. SO, it needs to be tied so it stays with the
main harness on the inside of the plane. This B+ lead is about a foot too short so make plans ahead of time.
Note (2): The P-Lead connection to the Magneto switch is also about a foot too short. Make plans for it.
Note (3): The tach lead, as far as I can tell, is useless. They provide a signal out but there is no signal processor to
make it work with digital tachs.
Note (4): There is a secondary lead on the harness section to the MAP sensor. SOOOO. You need to make sure the
MAP sensor is on airframe ground.
5) Installation instructions: Pretty much substitute the word "than" for the word "then." Don't know about you but I find that . . . .
Note (1): There is a note that says "• Built-in timing monitor" but I can't find where it is.
Note (2): They recommend NOT using a Breaker Switch for the 2-amp circuit. They want you to install a separate switch. That makes no sense to me.
Note (3): The instructions describe where to install another switch to turn the MAP on and off but the wiring diagram shows nothing about it.
Note (4): Wiring diagram shows an LED line but it was marked "optional." I had to determine if it was really wired for it or not. NOT.
6) Plug wires: They are cut to fit. You'll need to install the nuts on the cut ends.
HOWEVER, the nut is so tight that it is almost impossible to get it on.
PLUS, the rubber seal looks like it was cut out by hand and the hole in the middle is NOT IN THE MIDDLE. Very bad.
This makes the nut which you use to tighten onto the plug VERY DIFFICULT TO TURN.
7) Wants: a) Shorter wire from the MTH or plug directly into the MTH
b) If there is no way to shorten the cables, at least put them in expando sleeve
c) Longer B+ lead
d) Longer P-Lead
e) Combine the controller and MAP sensor into one unit.
f) Better rubber washers for the plugs.
That's it for now.
Gary
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