Bought this firetruck on a whim.
1978 W400 4wd. 360/NP445/NP230.
12,000 miles.
Going to yard all the firetruck shit off it and put a flatbed on it.
Part-time kit was already installed. Probably put a better ignition system in it and a 4bl manifold and carb.
Don't know shit about these things but it should be fun.
I'm super jealous.
I wouldn't ditch the factory ignition if it were mine. Factory Chrysler electronic ignition is dead reliable, the ONLY thing that you may need is a ballast resistor. If there's a black streak coming out behind the ignition module the epoxy is probably going to shit, cruise eBay for a NOS orange box (orange box give a slightly more aggressive advance curve IIRC, NOS only because I don't know how good the 'new supplier for MOPAR' boxes are) or a NOS Echlin NAPA ECM (the new parts store ones are shit regardless of the price). If it works fine now and the epoxy on the ignition module isn't cracked the ballast resistor is the only thing I'd toss in the glove box. Even then, it 25 years of owning 2 dozen or more 70s era Dodge trucks I've never had a ballast resistor go bad. The other thing you can do is get a resistor type coil and eliminate it (my brother's preferred way to fix the main known issue, I can get you a PN if you'd like but you can prolly find it yourself). If the wiring is sound the ignition system has never left me stranded. You could run a DUI ignition setup but things get tight to the firewall and I don't think they are as good as everyone thinks they are for longevity, at least the newer ones anyway. I've got a few friends that have had shit luck with them. If you go that route make sure you get one either set up with the proper vacuum advance or one that's adjustable. Factory full advance timing (mech and vacuum) on Chryslers of the era were only around 28-32deg compared to chebby and their 34-36deg. You'll hate life if you don't get it and the factory open chambered heads and cast pistons will hate life if you crank in a bunch of initial advance to make up for lack of vacuum advance.
The other option is a new replacement points distributor with a Pertronics kit, my brother has done that as well on his plow truck (wiring is minimal is why he went this route, less wires to corrode), works fine, but I can honestly say the factory electronic ignition is just fine.
Factory spread bore cast manifold and a tight pre-emissions Q-Jet (bolts right on, was the factory carb in the 80s) and you'll be set. You could run a Holley, Eddy, or Demon but I really like how my Q-Jet '79 runs with this exact setup after a rebuild (my Q-Jet was off a 1986 9000?gvw W250).
If you're gonna have the intake off, you might as well stab a cam in it. Factory specs were smog-era typical (garbage), made torque but if you want a 4bbl you may as well get some real extra performance. Whatever your preferred cam supplier's "torque or RV" cam will make a big difference (most of the specs for those are .440 lift, factory barely cracked .4). Dual pattern more better, especially if you can get some more lift on the exhaust side (for what you're doing that's really where the cork is). Intake side on those flow fine for stock compression truck motor. That thing may have the HD timing set from the factory, with 12k I'd reuse it.
The part time kit might have been factory (or dealer) installed from day 1. I have a 76 W300 setup like yours (was never a fire truck though) and I bought it from the original owners' son. He says they took delivery of it with the lockouts and part time from the dealer.
What axle gears you have? My W300 has 4.56s in the D60/D70 axles.
One thing I would do is bypass the ammeter in the dash. You probably have the higher output alternator. If it wasn't factory shunted (some were) I'd get rid of that IMMEDIATELY. Lost a 76 to fire 10 years ago after tossing a 10si on it (actually my brother did, I bought the truck off him). Really, with 50yo wiring the way Dodge wired the ammeter was dumb for anything other than the 35-40amp output alternators. You will probably see evidence of heat around the bulkhead connector where that wire passes through the firewall. That connection gets corroded, and the wiring was juuusst good enough when it was new. Then full charging current goes through the ammeter like it should for accurate reading (they do go bad) then out to the battery and ignition. Yes, that's how it has to be wired to read correctly, but ammeters became dangerous once charging current got above 30amps IMO. Bypass it before bad juju happens, preferably with a dedicated charge wire to the battery with a breaker or 30a fuse running through the firewall.
If you break a motor mount (they are not the safety type) mounts for an 80s LA truck will swap right in and give you that added protection. Don't buy the cheapest RA/ebay/amazon version, they are shit (I've done it, learn from my mistakes
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