308 GTB COIL WIRING, IS THIS CORRECT

Stock there are no amplifiers per se. The Yellows from the + on the coils end up on the left fuse block fuses 1-2-3 which is the ignition switch 'Run'. As long your red wires (black on the drawing) go to the distributor points , it looks ok to me. The brown feeds the tachometer and the 'Electrovalve Electronic Speed Switch. Is that what you refer to as amplifiers? I wish you had the full diagram...there is also a Fuel Vapor Fan Timer with the EESS with the cat temperature control circuits. Frankly, I get lost in your sentence which begins "Lastly," but perhaps this diagram will help you.

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If by "amplifiers" you mean the ballast resistors (mounted under the coils), what you have will sort of work OK, but, as you noted, the two banks are not the same. The "stock" set-up is per your rear bank (1-4) coil -- the red wire is connected between the "-" terminal of the coil and one side of the the ballast resistor; the black wire (going to the points) is connected to the other side of the ballast resistor. What the shop has done is connect the black wire directly to the "-" terminal of the front bank (5-8) coil bypassing the ballast resistor (and they must have moved the brown/black wire to the same terminal on the ballast resistor as the red wire if your tach is still working because the brown/black wire must be electrically connected to the black wire for the tach to work). This sort of works, but it will stress things (the coil, the points) more since there is no current limiting without the ballast resistor in place. Many people here have replaced their stock ignition systems with an aftermarket system -- I'd be very surprised if you couldn't get a free replacement ballast resistor from someone if you asked.

The schematic section that Paul posted might be from a different year as it shows the ballast resistor in an electrically-equivalent, but physically-different, place -- see the wiring diagram in section 5 and the ignition system figure 66 in section 3 on page 74 of the 150/78 OM (although figure 66 has a wiring error too ).

 

Good catch Steve. How many time have I said Ferrari never made two cars alike.
Below are 4 models and 4 variations on the wiring. Sometimes Ferrari has made obvious mistakes in the wiring diagram and carried it over to other cars, so I double checked...but here 4 ways of doing the same thing except for the 1975 308.

Ballast resistors are used to drop the voltage to the coil during normal run conditions to about 9-10v . They do this so they can boost to full battery voltage when the starter cranks because the starter can suck the battery down to 9-10v and otherwise reducing spark output. Bypassing the ballast gives relatively constant spark whether in run or in start and often a bit enhanced during start.

You may note the 1975 OM drawing omits the boost during start which is likely an error of omission because this circuitry was common even on lowly 50's-60's American cars.

So as long as the circuitry performs this basic function, all is good. There is NO stress or current limiting function or circuit preference to worry about as long as the ballast is in the circuit during run condition and bypassed during start.

Bottom snips taken from OM year indicated

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Hi , trying to keep to the thread topic rather than starting a new thread --- I need a diagram or pic of the correct wiring for the twin coils on the 1983 308QV USA. I replaced the OEM coils with he marelli ones with the HT wire a little offset -- but now there is no spark from the coils.... I need to double check my wire connections ( +/-) at the coils --- one coil - front bank - has all yellow wires -- the other coil - rear bank - has one green and one yellow coil on the + terminal -- I was careful to move them over correctly but now w/o spark - I am not so sure... A pic or diagram -- or even a description would be great and definitely save me trouble shooting time.

 

See the ignition system schematic on page 71 of your 260/83 OM or the complete schematic in Section 5 of your 260/83 OM.

The "+" terminal (terminal 15) on each coil should have G (yellow) wires. (These should be +12V whenever the key is "on".)

The "-" terminal (terminal 1) on one coil has GN (yellow-black) wires.

The "-" terminal (terminal 1) on the other coil has V (green) wires.

The schematic indicates that it's the 1-4 coil that the gets the V (green) wires and the 5-8 coil gets the GN (yellow-black) wires, but sometimes they get things swapped on the schematic versus reality.

 

Thanks Steve for the quick response... this is exactly what I was looking for. the schematics on line were too difficult to read , even enlarged, for precision.
The key on +12v was something I was especially needing to know... that is yet another trouble shooting test for me on this issue.
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