And both of ya are correctamundo! But the "hot wires" title got me going! We're working with another member of the fwb mafia down in medford that is running a dui distributor with the "hot wires" setup!
Brett... Trever has been going through nearly the same ignition stuff for the last few weeks as you, but his issue was related to installing the wrong ignition coil...and he was trying to work out some detailed carb tweeking issues when the real problem was ignition. Well not quite...his first carb rebuild was a real learning experience compounded by the ignition issues!
The resistance wire originates at the ignition switch "on" position. Total oem length of that wire run is 58" which provides 1.8ohms resistance (nominal) at 70*f, that is a stranded "ni-chrome" type wire with a fiberglas overbraid for heat protection. It does get very hot when the engine is running, it has to!! In fact, due to the really crappy way IH incorporated that wire run into the loom, it is very common that it actually burns in two, and takes out adjacent wire runs in the bundle also! That wire should have never been put up into a loom/bundle!
To make it worse, the wire is doubled back on itself, sometimes twice in the harness. The point where it's folded back results inna tight crimp which breaks through the insulation resulting in an extreme concentration of heat.
Add in that design deficiency, along with the absolute worst type/quality of oem bulkhead connectors known to the industry, ya got electrical issues that came right from the factory as standard equipment!
The 1.8ohm "run" feed to the coil, plus an internal primary resistance in the coil itself, provides a "saturation" current of a nominal 3.2amps at idle on the breaker point ignition. That current factor is also dependent upon the distributor dwell setting. This current factor is intermittently switched of course by the breaker points, or in the case of trever's distributor setup (delco) by the crane xr-I replacement module. Same thing holds true for a pertronix conversion (a pertronix II module is a slightly different animal).
The key factor here is the use of a coil with a primary resistance of between 1.4 ohms and 1.8 ohms for the sv (eight cylinder) ignition system. In other words, a coil with a "stock" specification on the primary circuit winding.
This whole issue of "coil resistance", ballast resistor, etc. Is grossly misunderstood and that kinda bsstuff is then compounded by regurgitation by folks who don't have a clue as to how this stuff works! And then the marketing bullshit form the ignition component manufacturers/suppliers takes over which really confuses things! We'll deal with this whole subject in another thread so it can be addressed separately!
Trever saw some of this type "info" demonstrated at the Binder Bee on various rigs we ran on the engine analyzer, nearly every vehicle had some kinda "dwell" issue, even the one's using a pertronix!
Inna re-wire operation, the resistor wire can/should be eliminated, unless we're talking a total restoration where originality is important. Simply substitute an external-mount ballast resistor of the proper value...1.4>1.8 ohms! And this holds true only if the entire ignition system being used calls for a "ballasted" feed to the coil on the run circuit. Many of the electronic conversions do not use a ballasted feed, so there is no general rule of thumb about this, each system needs to be looked at as a complete system, not just a component swap. Many of the "upgrade" components are not compatible with each other, contrary to what the various manufacturers May claim or allude to!
And I'm not talking about ignition systems which communicate bi-directionally with an ecu as used in some efi/electric carburetor apps. Those are a complete separate issue!
All the above is based upon an sv application, the exact same principles apply for any 6 cylinder or 4 cylinder system. However, the resistance wire May be supplemented by inclusion of an additional ballast resistor and a coil with a different primary winding resistance factor, along with a different dwell factor...all of which determines coil saturation and primary circuit current draw for the individual system being serviced. There is no single wiring/resistance setup that is correct for all inductive/kettering ignition systems!
As for the bulkhead connector re-work...I personally do not like or use 'em! A terminal strip/barrier strip of the proper quality and ampacity is a far superior! Bulkhead connectors are/were only designed for an assembly line process. Mil-spec, secure gang connectors are certainly nice, but can be a pita to install if the existing wire runs are cramped for length/space.
If your bulkhead connectors dont' simply pull out, then that is because the male/female contacts inside the connectors have fused/deteriorated due to the fact they are not of the correct ampacity value for the circuit!! The poor connection intro'd voltage drop and extreme heat buildup resulted over time. I'm sure you will find 'em badly damaged! That 10 gauge wire run with the "screw-on" terminals is the main feed through the ammeter, which then supplies the fuse distribution system and is the charging feed to the battery (ultimately). The ammeter "feed" is a great design, but was simply poorly integrated by ihc electrical system non-engineering! I would never eliminate that system, but simply upgrade it to high quality componentry. And add a voltmeter to the system at the same time for total charging system monitoring.
Attached is a pic of an early sii with possibly the worst botchjob on one of the bulkhead connectors that I've delt with in recent history!!! A large portion of the resistor wire had been taken out and a piece of 20 gauge (!!!!) spliced in with scotchloks! And ya can see the 10 gauge main feed has been butchered too! This one had a resistor wire circuit meltdown right in my parking lot and actually caught fire while we were bs'n over the open hood!
All of this was delt with in a very "poorboy" (but safe) manner so that the owner could make it home. I simply installed a proper "used" resistor wire I had on hand stripped out of a melted wiring harness (I don't throw anything away!), and re-worked all the real trashy splices that had been done over the years. You can see that many po's had tried to bypass the bulkhead connector over time. This one is a prime candidate for a total re-wire! Ya should see the reat of the story!
