It appears to have a Duraspark system of some kind. I think D4AZ-12A199-C (BLACK)? I have always assumed it was the factory motor but I am not sure.
Could easily be the original motor still. And the distributor would be what is nowadays commonly called the Dura Spark, but in '74 (the first year that Broncos got it) they had not named it that yet. Other members know the sequence, but I think it was just termed "breakerless" (oops, there it is right in Viperwolf's diagram) before someone decided it had to have a catchy name to sell the new technology on the leery public. Leery of little "black boxes" under their hoods.
Yours would still have had the small distributor cap of old, but all the new electronic trigger mechanism and, in your case the Black module.
So that could all be correct so far.
The motor is a 74 casting but maybe an August 73 stamp?
The vehicle line confuses me, but maybe from the Mavrick line?
That's not out of line at all. An engine cast in August of '73 would almost certainly have gone into a '74 model year vehicle. Engines pre-date their vehicles anywhere from 3 weeks to 3 months. And August is the most common cutoff date between model years anyway.
What month was your Bronco built according to the certification label on the driver's B-pillar/striker post?
And engines put in trucks, especially Broncos, were not Bronco-specific engines. So the engineering number of a common Ford 302 would have been from a common lineup. Such as Maverick, or one of several other categories. So your part number searching is not steering you wrong. It's just that 302's were not truck-specific.
If I'm reading everything correctly from the glovebox and previous posts it is an August of 73 build date.
You talking about the Bronco now, or just the engine casting date still?
The warranty plate on the glovebox door would not indicate anything about the engine. Only the vehicle. The VIN gives you a known build sequence, but you'd probably have to get a Marti Report to know the exact day that your Bronco was produced. Some members have the info down to the day on some model years, but I don't think they have documented all of them.
The wires in the engine bay are mostly in pretty bad shape (mainly the connectors), but the wires under the dash are in really good shape. If the ignition system is factory I would prefer just go back with the same model unless Duraspark II is just vastly superior. I am hoping someone can help me determine exactly what I have so that I can go about fixing it because I am in a rut and having trouble finding diagrams that match what I have.
Which connections are bad? If the ignition wiring, you can easily swap out the old (I hate those) connectors for something easier to use like a Weatherpack or similar. But you'd have to also cut the connectors off of your two ignition modules if you wanted to keep them.
Or you can buy a pre-made Dura Spark II harness from several sources (Painless, or us for example), pick up a Blue module and just use that from now on.
I don't actually see anything wrong with keeping your current Black ignition modules if they work. It's just that the Blue ones were the last hurrah of the Dura Spark, and are usually the easiest to find and least expensive as well.
Your distributor would stay the same, unless it's worn out from age. Check it and see. But even a new replacement is going to be just like yours except for no guarantees it will have the same timing curve.
I would upgrade to the larger cap of the later Dura Spark systems though. At least when it comes time to replace the spark plug wires, go with a modern set and the larger, wider spaced cap with cap-adapter and use that instead. I prefer them with their male terminals even if the larger diameter was not an advantage.
You'll need the cap adapter, the new larger cap and new rotor. And the wires of course. And that's it. The distributor body was identical to older models, so the cap adapter snaps right on to your old distributor.
Replacing the connectors is not the "wrong" way to do this, but it would mean that from now on you'd always have to replace the connectors on any new modules you buy. Including one out in the middle of nowhere without your wiring tools.
So even though I prefer Weatherpacks WAY more than those dreaded Dura Spark connectors, there is a very good argument for getting the new harness and keeping that type of connector for future use.
Nobody (that I know of) is offering reproduction harnesses with the correct orientation for the eight or ten other Dura Spark models. Just the modules with the Blue strain relief.
Good luck.
Paul
