I've done alot of reading in the process of building my car but sometimes......o.k., all the time - you just can't beat good old fashioned experience. I'm about to start my SBC engine for the first time in about a week from now. Today, I installed the battery and turned the key to the "on" position to check some of the electrical system out. I'm running a stock 1970 GM small cap distributor and the points have been replaced by a Pertronix unit. In my reading, and after checking the ohms of my coil and blah, blah, blah, I decided to run a ballast resistor. I purchased it from Summit and it's mounted in a ceramic chunk / metal bracket. It only has one mounting hole, so I bolted it to the firewall, with the spiral of wire near the paint. I can't see any other way of mounting it, except maybe using some spacers to move it out/away a bit. Anyways, that ****er got glowing red hot (now I know why it's ceramic) after maybe 1 minute of the key in the on position - I never started the engine. My questions are these: 1.) is that normal? 2.) if I had started the car, would that thing cool down because the "juice" then has somewhere to go? 3.) should I spacer it out - is it gonna cook the paint? / where did GM mount them hot ****ers in the first place? Thanks for p***ing the torch of knowledge! Oh yeah, the back gasketed cover of my new $65 Speedway brand aluminum water pump leaks. I love Speedway!
I've never had a ballast resister get that hot. What kind of petronics system do you have? Some of the older versions need one but some don't. I remember chryco used to mount them on the firewall.
Are you certain you got a ballast resistor ? It all most sounds like you got one of the little ceramic voltage drops for dropping volts to a gauge . They are a spiral shape coil, ballast resister is generally a straight coil in a long rectangular ceramic block . .
Based on the info from the Pertronix website I would prefer a coil with 1.5 Ohms resistance. That way you can run your ignition wire directly to the coil without the worries the ballast resistor is causing you. This is from their website : What type of coil can I use with the Ignitor™? How do I check my coils resistance? (12V negative ground only) To determine if your systems coil is compatible with the Ignitor, some measurements should be taken prior to installation of the Ignitor. Caution… While performing this test, never leave the ignition switch on for more than 30 seconds at a time. Set your voltmeter to a 15 or 20-volt scale. Attach an 18 or 20 AWG jumper wire from the negative coil terminal to an engine ground. Attach positive (red) lead of your voltmeter to the positive side of the coil, and the negative (black) lead to an engine ground. Turn the ignition switch to the run position. Now read the voltage at the positive coil terminal. Turn the ignition switch off. If the voltage measured is approximately 12 volts, no resistance wire is present. A typical resistance wire will provide 9 - 6 volts. The next step is to determine the resistance in the primary ignition. Label the wires attached to the coil terminals and note their appropriate location. Make sure that the ignition switch is off and disconnect all wires from the coil. Adjust your meter to the lowest ohm scale. If you are using an ****og style meter make sure to zero the needle. Measure from the negative terminal to the positive terminal. Write your measurement down. Now the maximum system amperage can be determined, divide your voltage measurement by your coil resistance measurement. This will give you the system current or amperage. Four and six cylinder engines should not exceed 4 amps. Eight cylinder engines should not exceed 8 amps. If the total amperage in your system is higher than the amount recommended for your application, you should install a ballast resistor. Example Voltage 12 Resistance 1.5 12 / 1.5 = 8 Total amperage
yes, they do get hot...i always mount them away from anything heat will damage just so you know , the Petronix Ignitor doesn't like having the key on and not running. you can get away with that on the Ignitor II also....they also use different ohm coils
My Pertronix kit said specifically NOT to run a ballast resistor ahead of the coil! They need a full 12v. signal to work. I don't have a ballast resistor on either of my cars with Pertornix kits. I understand the newer kits say to use the ballast resistor if you don't have the correct ohm coil. If your coil is 1.5 to 4.5 ohms you don't need it.
Vall, since I know you are an electrician......when I touch the leads together on my Fluke model 77 on the ohms setting I get a reading........When mearsureing ohms on a individual component, don't you have to remove that initial reading from the meter it's self? Kind of like tare weight on a scale?
Plumbid The digital meter (Fluke 77) should go to zero ohms when you touch the leads together, but you don't have to "zero" the meter as was done in the good ole days with battery operated meters such as the Triplett. You touched the leads together then turned a pot to "zero" the needle on whatever scale you were on.
This is how it was done in 1964. It was common practice to have one mounted on the fire wall. I mount mine out in the open because it was the traditional way to do it. Yes they get hot that is where the voltage goes. When the billet craze hit we started to hide them but to me a ballast on the firewall just screams hotrod. Hiding the resistor and wiring is not a traditional practice. It's part of what makes the car run...celebrate it. My 56 Ford is running a reproduction 57 Ford ballast resistor which is quite distinctive and mounted on the intake manifold. I love it because it's different. Yes I use it on my Chrysler electronic ignition.
Always ran a ballast resistor mounted on the fire wall, never paid any attention to it as far as heat goes.
I touched one for the first time in 1965. It was some kind of hot. Never touched another when the key was.
Yes, you have to subtract your lead resistance from the measured value to get your true reading. Your lead resistance will be made up of your actual wire resistance, and socket/plug resistance. Always do this when taking a reading on on a low ohms scale.(less than 200 ohms).
I'd be shocked if a Fluke's leads gave more than a tenth or two resistance. Not enough to even consider in the larger resistance of a coil. If your initial reading doesn't clear or disappear when the leads are separated, then the "hold" ****on might have been bumped and it's holding the reading. It should read "OL" when the leads are separated, and then display the coil resistance when you check it.
All this started when I read this thread: http://www.jalopyjournal.com/forum/showthread.php?t=745938 I think the thread is great and it taught me stuff. I not only like building hot rods, I like to fully understand what I am doing. I looked at plenty of "early" stock wiring diagrams because I had to build the harness into my Plymouth, but more along the lines of an old GM product. The only reason I removed the points was maintenance reasons. There's always stuff to do on old cars and to be able to erase just one thing allows me to do something else. There's never enough time. My Fluke had an issue. The leads are "sprung" where they plug into the meter itself. Well, mine are old (1992) and they had lost their tight fit. I was able to spread the connection point inside the leads and viola! .1 ohms - it was much higher before. The reading on the coil before was "corrected" by myself, so I got the same overall result today - 1 Ohm on the coil. I am running a Pro-Products coil, but I removed their sticker. I bought their coil because it was one of the cheapest coils that came with a mounting bracket. According to Pertronix (and has been mentioned here) they want a coil with 1.5 Ohms or more. I'm quite sure I've got the right part combination - I've just never dealt with a ballast resistor and was kind of surprised by how hot it got. Tommy - that photo is AWESOME, I spotted the resistor in about 2 seconds! Your post made me feel tons better, my install is very close to what is shown in your photo. I won't leave the key "on" ever again, which is the norm for any old car. I'm ***uming when the car is running that the resistor won't be as hot. Now I've got to rip my cooling system apart to fix that effin' water pump! Please excuse the booger welds on the firewall, I run full sheet metal!
this was done in 97 and not 64 but it is a Chrysler electronic ignition done up like we did it in 64 for points. Can you tell?
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