Not really , the twin eight distributor uses two coils and often both fire at the same time. The biggest use today is on the dual plug flathead,and they fire at the same time. However they could be adjusted to unsync and fire at different times..
Why does my customer's GM crate FB385 call for marine spark plugs? If I understand it right marine plugs have more resistance at the plug? What exactly is taking place there? Loving this thread, hope it continues on.
Great read Bubba! Ford model A ignition system. Would you still use a stock system? I have a stock system on my flathead banger, like the way it looks and would like to keep it while hopping up the engine. Nothing crazy, under 5000rpm and under 100hp. Btw I like the manual adjusting. Starts easy, doesn't miss a beat, can rev without misfires. Keep it or loose it?
On the Model A our Mallory unit is made up out of new industrial unit . We tear down , machine and readjust for 30 degrees of spark advance at 2500 rpm. These really wake up the Model A engine..... $250 and comes with cap, rotor and ignition wire set.......
Yes it would help. Mallory made bracket with a switch and a blue light in the 60s. It mounted under the dash and said street and race on the front. When the switch was ran thru the ballast it was in the street position and when it was switched direct with no ballast it lit the blue light and said race. I have one at the shop , will post a picture today sometime...
Pretty simple actually, just run a good wire from positive battery to good quality switch ( some are poor) to the positive side of ignition coil. That would bypass the ressitor by feeding direct battery to coil. I have a fond memory of riding in a 63 Ford four speed car with medium riser 427 dual quad engine with this switch under the dash. Left from a red light wide open , what a ride ! I always thought it had something to do with that blue light under the dash !!!!!!
That doesn't sound quite right, does it? I guess it could be an issue if you actually had a TH400 and were using the same kickdown switch for both functions. Then a diode might work to stop a backfeed. But if you don't have a TH400 you could just add a kickdown switch and use it only for a 12v feed to the coil at full throttle. You might try GM switch #1242101. It attaches to the accelerator linkage under the dash but I don't know how adaptable it might be for a vehicle not originally offered with a TH400.
You guys are over engineering the wheel!! Do it just like Mallory did it , add the cool little bracket with the blue light to show when switched on, then tell your pals "watch this" the glow from the blue light alone will add 30 horse power !!! Kinda like when i was a kid at the gas station. People would come in to have their carbs adjusted. I noticed the ace mechanic would turn the air screw in one turn and then back out one turn, and say try that. Often the cars owner would come back and slip him a buck or two saying that fixed it..............oh well????????
Thanks a lot for this great thread! You´ve answered more questions here than I ever thought I would have before I started reading, haha... It ´ll still take me some time to understand all of this. Well, I´m just trying to figure out my own ignition flaws. I have a 355 SBC, 10.5:1 cr,234/244 @.050 lift, T350 with 2400 stall converter,3.36 rearend, AC Delco points distributor with pertronix kit and a Mallory coil. Cruising around town at low rpm the engine has a bog and a mis before it takes up speed if there´s a slight hill or under very light acceleration. This only happens when I depress the throttle very little under very light acceleration. When I give it a little more throttle slowly the bog gets worse until the engine roars to life and scares the the hell out of the passengers,hahaha... I´ve tried different carbs and calibrations, leaner richer... it stays the same. It obviously has something to do with the transition between idle and part throttle... Now I tried limiting the vacuum advance to 10° and mechanical to about 20. Intial or static timing is 12°BTC right now. Feels like it helped a bit, but I haven´t touched the mechanical advance springs yet. I also have an MSD distributor on the shelf I could use, but I prefer the looks of an old AC Delco in an open hood Hot Rod.
Bubba, You are the man in my opinion .What a great thread to share all that info with us. Thank you...
Mags are used in aircraft so they don't have to rely on aircraft electrical systems for spark. If you're flying along and your alt or gen craps out, you don't want to have to hope the aircraft battery will power radio,lights, etc. AND ignition till you can get it on the ground.
Sub'd With all the various options out there for plugs, wires, etc it can get confusing on what works well with what, thank you for straightening it all out for us. Kipp
What a wonderful and informative thread! Here's a question which I hope GMC BUBBA may address. I have just acquired a spare engine for my 4 cyl Formula Ford open wheeler race car. It has a Unilite distributor and I am confused about what coil to run with it. I would prefer to run a resin filled coil, because of vibrations, and without a separate ballast resistor. I have spent much of the day searching on the net and have generally come up with the info (probably mainly targeted to V8s), that I need a minimum 1.5 ohm coil. However on reading coil requirements for Hot Spark Ignition (which is magnetic trigger, not optical) they state 1.5 ohm for 8cyl but 3 ohm for 4 cyl. Does the same apply for the optical Unilite? Should I run 3 ohm because it's a 4 cyl? Thanks in anticipation. Russ
OK. I've sussed out the answer. 3 ohms because with 4 cyl the coil is energised for much longer. Simple really......
yep and the best 3 ohm out there is the "Bosch Blue" off ( or made for a VW beetle) jump on ebay and look for a bosch blue coil for part number...
Subscribed. I thought I knew a little about ignition systems until I read this thread. Now I know how little I actually know about them. But I'm learning. Who says you can't teach an old dog new tricks?
Jim, are you still doing ignition repairs etc? Been trying to reach you via tel, email and PM. Got a ZB250 that needs help.
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