DUAL IGNITIONS FOR TRAIL REDUNDANCY
Page 2, thanks for following along...
Here is a shot of the Delco Distributor with dual Chrysler triggers.
Here is the Phased rotor base installed along with the MSD Cap-A-Dapt adaptor.
Although a stock cap and rotor will still work, I'm not one to leave things alone.
This cap and cap/wire tie down are from MSD. 
Click for larger image.
Mounted 180 degrees apart they trigger at exactly the same time.
Notice there is plenty of room for dual triggers in the small Delco distributor.
Click for larger image.
Now I can run the larger Ford Style distributor cap with all of it's advantages.
If this were a Chevy engine, this arrangment would fit between engine and firewall where a GM
HEI distributor would not fit.
A real sloution for tight fire wall clearances.
Click for larger image.
This is a 'Phased Rotor' from MSD, and it allows me to phase in the rotor to the center of the
terminals when that terminal is being fired.
Notice the slots on the top half of the rotor? These let me move just the rotor nose where I
want it.
Click for larger image.
MSD currently has an even more cool tie down that will work on this arrangment, or stock V-8
engines running my large cap upgrade.
Click for larger image.
This is how I supply air from my On Board Air system (OBA) to keep the distributor
pressureized.
Positive pressure keeps any water or debris from entering the distributor.
If you don't have an OBA system, you can easily use a 'Bait Pump', an air pump that is battery
powered, ment to keep bait fish alive.
Just a few bucks at the local discount store...
Click for larger image.
Here is the coil set for the dual ignitions.
Dual coils are required for this particular set up, and I've chosen the Ford style E-core coils.
Notice the 10 gauge wire both into and out of the coil connectors.
Click for larger image.
Here are the dual modules, one Ford style, One HEI style.
Pardon the rats nest of wiring! This is what it looks like when I'm devloping this stuff and
collecting data.
I promise (when time allows) to update the wiring and post new pics if it.
Here is the diagram of how to wire the switch between the ignitions...
I've been collecting data from the separate ignitions for 4-1/2 months now, and I have a pretty good sampling for comparison.
Keep in mind that I'm using twin triggers exactly 180° degrees apart so distributor timing doesn't vary for each ignition.
Each ignition is using exactly the same kind of plug wires, coil wires, cap, rotor & plugs.
After about 8 weeks I switch the mag trigger feeds just to make sure the samples I was getting were on a level playing field.
Although both were fed by 10 Ga. wires through 30 amp relays, the amperage to the DuraSpark module was limited by the
wiring incorporated into the module that couldn't be changed...
I'm sure this affected performance quite a bit.
The HEI module in a GM vehicle suffers from undersize wiring feeds and too many connections on the way to the coil
I corrected this by using 10 Ga. wire for both the feed and ground.
The undersize wire on the GM HEI coil it's self is a problem.
GM usually uses 10 or 12 Ga. wire to deliver, but uses very small wiring internally to the coil.
This problem was corrected by dropping the HEI style coil in favor of using a Ford style E-core coil.
The Ford style E-core has many advantages besides the ability to use heavy power delivery wires, so Ford E-core was in fact
the easiest way to make serious ignition power.
Faster & Easier starts belong to DuraSpark.
DuraSpark modules have a cranking retard circuit that does it's job really well.
Quick starts even when the engine was flooded or extremely cold or hot.
(HEI doesn't want to start when flooded)
Cold start idle.
This one surprised me, I expected DuraSpark, but the HEI module did the cold start idle better.
Stop & Go town driving,
DuraSpark all the way. 7% better fuel mileage than HEI.
Town milage sucked either way, so this isn't what I'd call 'Definitive'...
Rural & Highway driving.
HEI by 6%. Rural and Highway is mostly what we have around here, so I got plenty of good samples...
Highway acceleration belongs to HEI by 5.4%.
Standing start acceleration belongs to HEI by less than 1%.
I don't have enough clutch for standing 1/8 or 1/4 mile times, and besides, a CJ-5 would look pretty silly doing timed passes
through the lights!
On 09-July-06 the little Junk Yard Jeep did it's first serious off road pass at Red Bird state ORV park.
Some of the mud holes can only be described as 'Bottomless Pits'!
I'm talking 37" boggers on another guys Jeep disappeared, so I didn't stand a chance!
I coated everything under the hood with a thick coat of sloppy mud and water and the unprotected contacts shorted out on the
HEI ignition module, in the middle of an Indiana 'Sippie Hole'...
Things looked grim as the engine refused to fire up again...
Not being too bright sometimes, it took me a minute to realize I had a back-up ignition,
So with the flip of a switch went to the DuraSpark ignition without ever having to get out in the mud and off we went!
Since I'd already nearly been knee deep while trying to strap up when I bottomed out in a hole, I was REAL GLAD I didn't
have to wade around in the mud again!
The epilog to this is more than one person in the group commented on the different sound when I switched over from one ignition
to another!
Why it would sound different, I have no idea!
Combustion should be combustion, but four people familiar with Jeeps commented on the change so I'm sure there is something
to it!
Just an oddity I though I'd share...
I'll post more when I get time...