I’m starting to wire my car from scratch and a friend suggested that instead of wiring 12V from the ignition switch directly to the coil + terminal, to route the wire from the ignition switch through a toggle switch and then to the coil + post. The purpose being, to allow the engine to turn over, before, providing power to the coil, for faster starts. He does this on his drag car and says it starts much faster & easier on the starter with that configuration. I’ve never heard of that before and was wondering if that’s common practice and what the pros & cons would be, if it’s done. Also, please be advised I haven't wired a complete car in 40+ years or so and any & all suggestions are appreciated - I'm 80 years old and am not nearly as sharp as I used to think I was! Thanks -Bob
I don't know about race cars or anything for that matter, but it seems you'll still be cranking the same amount with or without the ignition on. The only way to a faster start from a carbed car that's been sitting for a few days (drain back inside carb) is an electric fuel pump and a working choke. My panel has a stomp starter button, kind of the same idea as I can crank it with the ignition off (which sometimes happens by accident).
It seems like wiring in a ford starter relay would cover all your bases for both starter and ignition. Are you now using a ballast resistor ?
I remember back in the Ole days guys around here doing it on race cars, never seen it on street cars. Theory is it allowed the engine to come to unloaded "cranking speed" then setting the fire to it. Don't know if that backyard Theory had any real strength behind it. I do understand the thinking behind it though. Getting the mass spinning before putting starting load (ignition) against it, a mass in motion kind of thinking. ...
It helps with high compression ratios and engines that have a lot of advance a starting rpm Usually a locked distributor at say 34 degrees. Allows bypassing the spark until the engine is at a good starting rpm. I think I was as clear as mud. Dan
I'm a firm believer in less is more. Nothing less than 12 ga. wire anywhere in the stock circuit, solid terminal connections (good solder joints if you know how) and use a mini starter instead of the big stock type. However, none of this will help if you leave the machine sitting for a long time and the fuel drains back---then go with the electric booster pump to assure fuel to the stock pump or whatever. Mine sits, fuel drains back, no electric pump, just some starting fluid sprayed in the carb--the little start that gives is all it needs to run.
that is the way to start a car with a magneto you need around 250 rpms to get enough spark or any spark from a magneto it probaly will work on a battery style ignition if it had start issues
We do this on Top Dragster that I crew on, since the timing is locked. If it kicks back while trying to start, it will knock out the flex plate ring gear. I see no need on a street car unless you're running crazy timing with no advance built into the distributor.
Are you building a race car? I didn't think so. A practical, street driven rod does not need this ignition trick to start easily.
We would start our old dirt track cars by spinning the motor, then turning on the ignition, but we had full locked timing advance. All of my street cars have had electronic electric fuel pumps for years, even back when I ran carbs. I nearly always turned on the ignition to run the pump about 20 seconds, before I cranked the motor. With a properly set choke, the motor usually fired on about the 2nd or 3rd cylinder firing, once the motor cranked. With the EFI stuff, its turn the key and crank the motor at the same time, any other process increases the cranking time.
While hotrods are street driven , I doubt most anyone ever viewed them as practical , that's what hondas & Toyota are for ..
On a couple of mine, if they sit for extended periods then they lose their prime and have to pump some fuel. Once I've started them once it's not an issue. What I'm saying is unless you have a problem starting when you're making stops along your journey that day, why bother any extra complications? Mechanical fuel pumps, carburetors, and cranking with the ignition on work fine for me with relatively moderate compression street driven vehicles.
OK, thanks for the input. I got the answers I was looking for, which were "why" & the pros & cons of doing it. Never said I will wire it that way, just wanted to learn.
I don't see anyone mention the detail that when you control ignition separately you can wait to activate it until you see you have oil pressure - simply not to put a high load on any engine parts before you know they've got oil. Can be a good idea on a very expensive, very high performance engine.
Correct. An engine with locked timing will fire well before TDC, so the starter can be fighting firing pressure. A proper distributor with functioning advance doesn’t have the same issues.
As others have said, it does help a lot if you have high compression, and advanced/locked timing. It has nothing to do with a carburetor that is low on fuel.
On SBC & BBC & other engines Usually you do this when your Initial timing is around 18 deg befor TDC & higher or High Compression , & some engines when Hot hard start , small or low cranking amps or low charge . My self pretty much all my engines are wired with a separate Ignition On /Off Including my lawnmower tractor !! But that's me.
Henry Ford wired his cars as described by the OP between 32 and 48. The starter button controlled the starter and the toggle switch on the steering column controlled the ignition. Being able to spin the starter without ignition allows the engine to build oil pressure before firing as well as allowing rotation of the engine for maintenance procedures. In todays world it can also act as a theft deterrent.
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