This is an adapter unit that puts a GM HEI control onto the Ford trigger unit. The Ford trigger units are so bulletproof it hard to find a dead one (that hasn't been phyically injured). The one in my bird got about 145,000 miles in a pickup before I became the "new" owner. The Ford style controller units don't like a low resistance coil or no ballast resistance - they overheat. 

This will work with a low resistance coil and no ballast resistor. It has a "smarter chip" than the Ford boxes and uses dwell time to control heating of the transistor. This is what it looks like built onto an aluminum heat sink plate the same size as the Duraspark II controller.

I refitted my outfit with an MSD low resistance "TFI" coil and a lower ballast resistance so the total was about 1.8 ohms. The Ford type controller (a Wells unit) didn't like this much and imediately started heating up at low rpm. It did make a significant visual and audio difference when viewing an open plug firing out on the manifold. Nice blue sparks and "cracking" right along.

This new unit was installed with "jumpers" for a test. The ballast resistance was then removed so it was firing a coil with only .9 OHMs internal resistance. It looks (and sounds) like a little arc welder - and the module doesn't heat up like the Ford units do. You must have a #12 or larger hot wire to the coil + - and it needs to come from a power relay not some old dash switch. This thing has a considerable thirst for AMPs and Volts. The idle actually improved a bit - I'm pretty sure it lights the fire no matter what.

New HEI module (standard 4 pin type) is dirt cheap - I got this "hot" one off ebay for less than $20 - the regular type HEI's are available at virtually every auto parts outlet. Spare fits in the ashtray and can be changed in minutes with no burned fingers. The Duraspark style system with divorced trigger and controller is far superior to the Pertronix in terms of troublehooting and repair (changing parts). The hot chips like the one shown here have a higher capacity for heat and an even smarter dwell computer - pushes the effective rpm up over 6000 revs (not for me).

This is old news to some - I've just been slow adapting it to my green machine. There are guys around who claim their hybrid set-ups have been running with this arrangement for years - I'm going to find out for myself.

These HEI controller conversions are all over the internet and I wanted to try one on for size. It appears to work just as advertised, and you can't beat the price. One atricle I read claimed that with the right four pin module (extended dwell set-up) it would out do any inductive system on the market - and from what I've seen so far they are correct. Only an MSD red CD box would be a better choice in my opinion (for pure spark power) but they don't get fixed this easy either.

I fitted the distributor with one of the "mustang" style HEI type caps to get a better high voltage isolation system - Ford thought it was a better idea so who am I to .....

disagree, right?

Holun put his Duraspark module under the dash inside - I'm sure there must be as many ideas as there are mechanics. I've been looking at an old emptied out "Motorcraft" module as a way to build a "Ford" cover for the gadget.
 

       Very interesting, You could sell a few of those, maybe scare Pertronics out of their lethargy. 

This system relies on use of the control module of the early HEI system dating back to about 1975. It is popularly called the "four pin module" - may have been used until the mid eighties(?) If you are confronted with a parts counter guy that has to have a "make, model, year, da da da" - tell them you want the module for a 75 Camaro, 350 cid. All of the four pin modules I've seen have the same 4 code letters over the connection tabs.

In the performance catalogs and at the speed shop, there are four pin modules sold as high performance replacements. The Accel module in the photo is just one of many that have the "extended dwell' timing chip. MSD and others sell a new version that supposedly will make sparks clear up to 9000 rpm - and have a built-in, adjustable rev limiter - but they are also $80 and not many Y's spend time doing that sort of crank speed. 

I think its best to use one of the "E-core" style epoxy coils, the Ford TFI type is my favorite because its cheap (and has the neat clip-on connector) - even the perfornance versions are not too pricey due to the popularity of the 80's Mustang 302's. Pay attention to the grounding - the black wire on the module diagram usually goes clear back to the distributor in the Ford wiring scheme - and I add a jumper lead that positively grounds to the intake manifold.

You retain the Y mainshaft and gear, the advance mechanism - and swap in the upper rotor shaft that is turned down to fit the reluctor (no point cam). Have to use the later style vacuum can with the dogleg. Look for an upper rotor shaft that has one of its slots labeled "13L" - and use it for the mechanical advance limit

There is an earlier Y distributor - but also post '57 - that uses a different style of upper rotor shaft and centrifugal advance mechanism. These have to visit a machinist to get the cam cut off and the proper fit turned on them for the reluctor. I have a print (PDF file) I can send you with the spec's for this older type unit if you send me a PM with an email address. Once you have this part everything else from the later donor distributor will work OK.

This one has had its slot altered to get a little less total mechanical advance (so you can run more initial advance without "over-advancing" at full travel).

http://pages.sbcglobal.net/mshum/HoLun/WIRINGSCHEMATICT-BIRD1.jpg

Steve, does the reluctor come off and go on easily once the roll pin is driven out?  It all seems to be stuck together as a unit until the reluctor is removed.  I had to destroy some advance springs at the junkyard in order to get one of them out of the distributor.  I managed to get the springs off of the other with a screwdriver through the hole in the plate.  It seems like it could be a bit of a chore to swap advance springs.

I've built four of these distributors now and had to polish the upper shafts a bit to get the parts to slide together with a snug fit. I put a new reluctor and roll pin in all four of them.

Step one is to remove the vacuum can  - then pull or pry the reluctor (armature?) up off  the shaft. The stator coil with base plate and pivot mechanism is next. This photo also shows the "color" code Ford used for the various wire leads. Violet and Orange on the stator coil - Black is the ground to the distributor body coming back from the controller. Just barely visible is the loose end of the Green wire that goes over to the (-) side of the coil.

The Stator/baseplate/pivot needs to be in good shape - it can be disassembled at the pivot - but be very carefull of the lock ring. When I've got them all cleaned up and ready to go - I lube these joints with Motorcraft caliper grease - something that can take the temperature.

There were some things I noticed - I've never seen a reluctor that didn't just have the two roll pin slots 180° apart. If they did have some leeway to "advance" or "retard" the trigger it would be useful when checking the "phasing" the distributor cap. I thought about filing a new slot in one a time or two - but didn't try it yet. 

The stop pin that engages the advance limit slots - on all of the undisturbed distributors I've dismantled, it had a little plastic tubing jacket. Removing this cover would change the total travel in the slot by a bit - but I don't remember a "13L" or "10L" slot that didn't net the correct degrees at the crank when I left the tubing in place(?).

After all of the explanation they did - why no discussion of initial, centrifugal, and vacuum advance? Must be for "advanced" hobbyists.......!