So at this point, I have done it all.
TFI:
The TFI is a good upgrade for your Duraspark ignition system. Start with a quality cap, rotor, and adapter. Then make sure you get the best set of wires you can find, because good wires are very important to a quality ignition. I'd recommend a make-your-own set of MSD Street Fire wires. They are simple to make as long as you have a vice handy (I actually crimped mine with a bottle jack and the subframe of my car while I was at school).
For the coil, either buy a 1.5 Ohm canister coil OR buy a 3.0 Ohm canister coil and bypass the stock resistor wire in your harness. I used the 3.0 Ohm coil/bypassed resistor for a couple years somewhat reliably.
As far as I know, most of the TFI style "E-core" coils have very low resistance and would probably need a resistor added to them. These work better if you're installing a "Stealth HEI Module" in place of the Duraspark ignition module. Otherwise, you will probably have some kind of failure, be it coil or module. Keep in mind, absolutely NONE of the replacement/aftermarket Duraspark modules are made in the US, and many have reported problems with replacements. I used a 4-pin HEI module wired with stock connectors for a couple months and the car ran great, but unfortunately I believe it got a little water on it and shorted the module.
HEI/Skip White Distributor:
The HEI distributor can be convenient, if you do your research. Skip White sells one that drops right into the 258 for ~$60, and all that is required to hook it up is a single 20amp fused wire. However, the gear it comes with is reportedly hardened steel, and it could potentially eat the gear on your camshaft within a year costing you a fortune in repairs. In this case, you would need to buy an AMC V8 distributor gear (~$30), and a couple thrust washers to shim the HEI shaft to something like .030" end play. In addition, you'll probably have to adjust the mechanical curve with new advance springs, and you might need to get an adjustable vacuum advance canister. I ran an HEI like this in my 4.0 for a few months, and while it was reasonably reliable, I struggled with spark knock and finding the right timing advance. It never ran quite right. Furthermore, there is no provision for timing retard while you are starting the car, so the starter really drags until you get it going.
CDI:
I know, these are expensive and can't be trusted as a stand alone ignition. Hear me out.
I installed an MSD Street Fire 5520 CDI box with MSD Blaster TFI "E-Core" coil on my Eagle last night. Though of course I can't yet say anything on reliability, the car has never ran better! These are hooked up with my TFI cap set, all waterproofed heatshrink connections tucked away with wire wrap, and it idles stumble free at 600 rpm in drive. It even got down to 450 rpm due to my carb adjustment and wouldn't stumble like it was dying! It even has a rev limiter, though I doubt my auto trans would ever need it, and it couldn't have been easier to install.
This setup cost me right around $200 with the wiring harness to plug right into the Duraspark distributor, plus I get a $25 rebate through Summit. The best part is, I left the Pertronix coil and Duraspark module alone so my ENTIRE IGNITION can be swapped by quickly unplugging and plugging in 3 wire connectors. That's right, a redundant ignition! I'm a hair away from being able to flip a switch
If you can afford it, I would strongly recommend this route for reliability and even safety sake. An ignition is not something that should be failing, take for instance GM's $1.3 billion recall because of faulty ignitions
Topic: Best TFI/Big Cap Upgrade Best Practices? (Read 14939 times)