What did you do to your 365 GT4 2+2/400/412 today?

I too faced the question of how I would (working alone) check the timing on my car. However I was part of the way to a solution because I had built a bench tester for checking my distributor timing after overhaul and reassembly. (I would have preferred to acquire a second hand distributor tester as suggested by Raemin in another thread on this forum, but none was available at the time).
The tester I built used two timing discs with opto switches, one on the distributor input shaft with a single slot, and the second on the output shaft with slots at 10 degree intervals BTDC. I made up two simple optical switches using opto couplers with basic circuitry and fed the signals to my (vintage!) oscilloscope. The tester was driven by my small milling machine which has a variable speed inverter drive. The results were very satisfactory and I was able to prove the distributor advance curve was to specification after I had completely overhaused the distributor.
Anyway, having satisfied myself that the distributor was working properly I then had to work out how to set the timing on the car. So I used one of the two opto switches and potted it in epoxy. I made up a new timing disc which I mounted on the harmonic damper on the crankshaft nose, and made up a bracket from the bottom of the A/C compressor to hold the potted optoswitch. The position of the timing disc relative to the optoswitch was "calibrated" against the flywheel timing marks to give me the correct TDC signal, and I also had the further signals at 10, 20 and 30 degrees BTDC. For the ignition signal, I used an old clamp-on pickup from a Sun engine tester.
The pics below show the setup. Pic 1 is the distributor test rig mounted on the table of the milling machine. You can clearly see one of the two circuit boards on which the first opto switch is mounted. The second circuit board can just about be seen at the bottom left of the picture. Pic 2 shows the upper timing disc with timing slots, and Pic 3 shows the lower disk which has just one timing slot. Pic 3 taken from underneath the car shows the third timing disk mounted on the crankshaft damper, and Pic 4 shows the potted circuit board mounted on a 25mm X 3mm bracket which in torn is bolted to the bottom of the A/C compressor. Pic 5 shows the oscilloscope trace from the bench test rig (upper pulse is the "TDC" reference mark, while the multiple pulses are from the 10 deg slots on the second disc). And finally Pic 6 shows the oscilloscope traces from the running engine, with the upper trace showing the clean pulses from the opto switch, and the lower much noisier trace from the sensor on the plug lead.
I'm not saying that this is an easy way to get the job done, but it worked! And the whole process of timing the ignition could be carried out in comfort without carrying out any acrobatics beneath a running V12.

Image Unavailable, Please Login


Image Unavailable, Please Login Image Unavailable, Please Login




Image Unavailable, Please Login




Image Unavailable, Please Login



Image Unavailable, Please Login




Image Unavailable, Please Login




Image Unavailable, Please Login

 

Highly impressive work!
I've also been looking for a distributor tester here in Germany, but I haven't found any so far...

I'll put some markings on the harmonic balancer to be able to check the basic timing, but in the long run, I'd like to fully digitalize the ignition similar to Peter in this thread:
512 BBi tdc sensor | FerrariChat

Cheers

Esben

 

Very…very…clever! Necessity is the mother of all invention! Kudos to you.
Karina (my 400) is currently getting an engine overhaul during which time the ignition, distributors and timing were restored. I love to learn how to tune these carbureted engines…. But I think I’ll start with a single carb small block Chevy!
Cheers and happy new year

 

Wow... rebuilding my whole distributor tester seems like a piece of cake compared to this "side project"

 

Had To buy three 42mm refurbishing kits in order to identify a proper substitute! At least these were cheap, but I only used the dust shield (spring is hard and has sharp edges, the inner seal is thicker than the one from frenkit).

At the end of the day the ate greases did cost more than the rubber bits. The piston grease is expensive for what it is: looks similar tonthe food compliant grease I am using in the kenwood major (at a cheaper price). I presume the old formula (with blue cap) was more specific.

Image Unavailable, Please Login