The Stovebolt Site Forums The Shop Area Engine Shop Do I need a starter switch with a side terminal?

Well I test started my 235 engine for the first time today. It sounded good but I am wondering if I need a different starter switch with a side terminal. My old starter had the side terminal but my new starter does not. I am thinking I do not need the side terminal because I am running a Flame thrower coil that specifically says use without a ballast resistor. My understanding of the side terminal is it is used to put direct power to the coil while cranking for a stronger spark and sort of bypass the ballast resistor. So in my case the side terminal is not necessary, is that correct?

Thanks

that's what the side terminal does, so if your ignition setup doesn't need the full voltage bypass function, then you don't need that terminal.

Stock up on points- - - -you'll be changing them about once a month with that setup.
Jerry

There is 2 models of coils sold by Pertronix. One says requires the resister, one says to remove or bypass it. I have the coil that says bypass it. They wouldn't have you bypass something that is going to in turn damage your point would they? I was a electrician for 3 years but I really never dealt much with ohms and resistance or DC power so I don't understand it very well. If It would do me some good I don't mind installing a resistor.

Are you still using points? The Pertronix coils are for their electronic trigger systems- - - -absolutely not for one that's still using points to trigger the coil. "Flamethrower" is a pretty accurate description of what you'd see arcing across the points if you could see inside the distributor with the engine running. All those fancy names mean is "Here's somebody we can impress with a catch phrase- - - -let's take all of his hard-earned money we can!" People who sell those items don't really care whether it works for your application or not- - - -they're just greedy enough to take your money and invoke the "no returns on electrical parts" policy.

You really need to go back to a stock coil with "12 V Delco" embossed on the side, and a ballast resistor. It's hard to beat what GM spent untold years of research and many thousands of dollars designing to work with the system you have. Ohm's Law isn't hard to understand, and it's absolutely essential that you have a working knowledge of its application if you're going to work on these old rigs.
Jerry

Yeah I may just go ahead and do that. I originally I bought the pertronics coil and photo cell unit but I decided to return the photo cell and go back to the original points. I needed a new coil so kept the flame thrower coil thinking it was similar to the stock coil. I did notice in the directions as you stated it is to be used with the photocell unit only. So looks like I will be ordering a starter switch with a side terminal, a stock coil, and a ballast resistor and I will be a good shape. Thanks for the help everybody

The whole point of the primary (low voltage) circuit in a coil is to flow enough current to build up a magnetic field around the secondary (high voltage) winding. When the primary current flow is interrupted by either opening the points or turning off a power transistor or two, the field collapses and induces voltage into the secondary winding. The stronger the magnetic field is, the higher the secondary voltage will be. Coil magnetic induction is measured by a term called "ampere-turns". The magnetic field gets stronger (hotter spark) by either increasing the number of turns of wire in the primary winding, and/or increasing the current flow (amperes).

Conventional points have an upper current limit of about 5 amps. Solid state trigger units like the GM HEI or the Pertronix can carry much higher current because there's no mechanical switch (points) to arc and burn. Combining a low resistance/high current coil with mechanical points is inviting disaster. The ballast resistor protects the points by limiting the primary current during normal driving to a level the points can handle, while still allowing for a hotter spark during cranking by bypassing the resistor when the battery voltage drops due to the load of the starter. Using a coil with a built-in resistor results in a weak spark when you need a hot one- - - -during starter operation in very cold or very hot conditions. The Delco research engineers figured all this out way back in the mid-1950's when they designed the 12 volt ignition system.
Jerry

Thank you Jerry very informative. I pretty much figured a coil was a coil and a high voltage flame thrower could only be better. I had no idea it may damage the points.