1KULC7

NCRS folks on their forum are familiar with this topic, but I thought I would through this out to this forum for discussion. Since something very interesting happened to me this week end regarding these resistor and ignition system on the 63.

My 63 is finished and I have the L76 Engine (340 HP). It has been restored back to factory speciciations so I have solid lifters, etc. The only difference is I have a larger volume vacuum can (really has nothing to do with were I am going with this). In the past I have had nagging problems with cold starts, and when I am driving the engine (it Boggs out) hesitates, like its going to stall from a stop in first gear, and then catches again. I also have gone through two sets of points, burned them out...with hardly no drive time, maybe about 150 miles combined.

Because of NCRS, I started to read some old TSBs from the 63 era, and found that by the end of the 63 production year, the 63 using the 091 coil went from the .03 Ohm ballest resistor to the 1.8 Ohm best resistor. It appeared there was a problem with points burning out prematurely using the .03 Ohm resistor. If I read one of the TSB correctly they said for the Fuelie cars they recommended one resistor for summer and one for winter???? Although the TSB's were not very clear of what to really do, I did what I think they recommended, use the 1.8 Ohm instead of the .03 ohm.

So I checked mine and I did have a .03Ohm, I changed it to a 1.8 Ohm and almost immediately the car did not have cold start problems, it the hesitation disappeared. I cannot argue with what I am experiencing, but I have to ask, does this single component make such a big difference. John Wiz or Duke can you enlighten me on this subject matter. I did nothing else accept change the ballest resistor from a .03 to a 1.8 ohm, and car works much much better

Comments:

magicv8

Here is more than you want and most of the opinions on what rpm gets improved by low/no resistance is contradicted:

Ballast Resistor removal: The result is great sparks at low rpm because of the time allowed for build-up of coil current to saturation levels. As rpm increases, this time becomes shorter and saturation currents are never reached. Weaker sparks are the result. In the old days, engineers circumvented this problem by introducing a current regulator to adjust maximum currents higher with increasing rpm. This regulator is a ballast resistor. Its resistance is dependent on TEMPERATURE, which is again dependent on average current through it. The device is embedded in highly radiant porcelain which liberates the heat generated in the device. This system is a crude analog computer or servomechanism in the most liberal senses of the words. The total performance of the ignition system is improved by its use. Voltage is insignificant. Because of the internal resistance of the battery, significant potential energy is lost during starting. For this reason the ballast is bypassed during starting such that full potential energy may be delivered to the ignition system.

Ballast resistor judging: from Jack Humphrey: There is a 'malady' situation for judging where there are rather lengthy periods where we need to have electrical power active without the engine running. TI equipped cars and later (post mid-year) designs saved money by using controlled wire gauge runs inside the engine electrical harness to simulate the effects of a modest series resistor in line with points and coil primary. Original ballast resistors essentially came in two styles. The high performance ballast was a rather low resistance value (around 0.4 ohms) and was used on high end engines where high rev profile demanded lower 'ballast' (energy discard) on the coil primary. These are identified by a characteristic 'black dot' on the mounting band, AND if you snake an inspector's mirror around the back side of the resistor's ceramic case you'll find a small ceramic cover mounted over the resistor's wire windings (presumably to thwart accidental metallic contact of the wire winding to the mounting band -- short circuit the ignition primary!). The low performance ballast was identified by a blue band across the upper mounting lug (blue ink crossing the white ceramic). Typical ballast resistance was 1.8 ohms for this assy. Some judges look for originality by inspecting the metal mounting band for the script Delco Remy logo that was embossed. Also, some judges look for originality in terms of finding a modest 'squared tab' end adjacent to the resistor's mounting hole in the band. In my personal opinion, I don't believe the squared tab end = correct/original.... Why? Well, if you pull the original D-R drawing for this part and inspect closely you'll see it was a PURCHASED ITEM! Despite the fact known originals have the D-R scrip logo embossed, these were apparently bought rather than made by GM. In my humble opinion, GM almost NEVER granted sole source status to a purchased part (if vendor goes on strike, GM shuts down!). Plus, I've walked many a scrap yard and pulled 'untouched' original ballast resistors off cars (some high performance, most low performance) and have seen quite a few with the D-R script logo deboss AND without the tiny squared off end. In my opinion there were multiple vendors then and it's possible for a correct original ballast to NOT have the squared end. But, that's just one man's opinion. Currently, what comes from Chevy and/or parts catalog houses does NOT have the tab on the end of the mounting tab.... Last, in the pre-57 era the ceramic was quite different (geometry and form) as well as the mounting band itself. So, the part changed over time in terms of assy cosmetics and the early ballasts are visibly different from today's service replacements. Also: C1 ballast resistor: There were several versions of ballast resistors in the years 1956 to 1962. A 1956 passenger car has 1.6 or so ohms resistance, no dot, a straight porcelain platform under the terminals and a "tab" on the mounting band. No dot or stripe. The dot-stripe thing started in C3 production. 1956 to 1959 resistors for Corvettes were 0.3 ohms (at 75 degrees), no dot, a tab on the band and a straight platform under the terminals. Late 1959 through 1962 had a tab, were 0.3 ohms, and were notched under the terminals with NO dot. All these were trade-marked Delco. An identical to 1956 passenger car resistor existed without the tab Also 0.3 ohms. The radius of the top of the mounting band varied and was not very pronounced in a 1.7 ohm non-Corvette version. Lastly - from Duke: my records show that the black dot resistor was .3 ohms. these are hand written notes. .45 ohms for transistor ignition. std ignition was 1.4 ohms. I most likely checked them with an ohm meter. '63 (spec's pages, at end of book) coil "091", ignition resistor "ballast", ignition resistance 1.4 to 1.62 ohms. [no part # given for ignition resistor]. '65 shop manual / spec's pages, at end of book: coil "202", Ignition resistor "fixed in wiring" [this must be an error], Resistance 1.8 ohms. [no part # given for ignition resistor]. For the "207" TI coil ('65 shop manual) they show: Ignition resistor "fixed in wiring" [correct this time], Resistance 0.43 to 0.68 ohms.

1KULC7

Great background information...Thanks

SWCDuke

First, the two ballast values are 0.3 and 1.8 ohm. The parts books says .03, but that is a misprint.

All early '63 Corvette engines used the 0.3 ohm ballast and 091 coil, but a running change was implemented to use the 087 coil and 1.8 ohm ballast on 250 and 300 HP engines, while SHP/FI continued to use the 091 coil/0.3 ohm ballast. This is documented in both the AIM sheet change record and the TSB.

The NCRS JG does not reflect this utilization and efforts are in progress to get the JG corrected.

The 0.3 ohm ballast yields higher primary ignition current for more spark energy, but was tough on points, especially in cold weather because the resistance decreases with decreasing temperature. Conversely, the resistance increases with higher temperature, which helps keep the coil from burning up if the ignition switch is left on and the points are closed.

I have no idea how your problem was solved by installing a 1.8 ohm ballast. The ballast is bypassed during cranking, so starting should not be affected by installed ballast.

I also have absolutely no idea what you mean by "larger volume vacuum can", so I have to cast a jaundiced eye at your entire discussion.

Suggest you remeasure the original ballast with a sensitive digital ohmmeter, and what coil is installed.

Duke

MasterDave

You want to pay ohmage to your ballast resistor? Ha, I kill me!!