V12 Running on 9

Is the cap loose?

 

Is it a dual point distributor?

If it is it is likely that one point set has failed. Perhaps just closed up.

On a lot of these Marelli distributors each point set fires 3 cylinders.

They need to be set up "off the car" on a distributor machine to synchronize both sets of points so they fire all cylinders at the right times.

You might be able to just reset it "quick & dirty" for the weekend if you're lucky.

 

As others have said, one set of point is for cyls 1,2,3 the other is for cyls 4,5,6. The point have not closed up, otherwise you would have no spark on cyls 1,2,3. Most likely a piece of dirt is in between the contacts. You don't need a distributor machine to set the points. Check the dwell, it should be 50 degrees. If only one set is working it will be 25 degrees. The point gap should be .014"

Once you have both points working, and the dwell is close to 50 degrees, you can sync the points with a timing light. Check the timing on Cyl#1, if should be on the AF10 mark at idle and should advance to AM42 when the engine is revved to 5000RPM or so. Rotate the distributor body to set the timing. Now check the timing on cyl#6 it should be the same as cyl#1. If it is not within a couple of degrees, you can move the points inside the distributor set for cyls 4,5,6 so the AF10 mark comes up at idle.

 

Interesting, my car has two distributors with single points. And Lucas.

 

Maybe its one of those obscure Ferrari V-3-6-9-12 engines.

Seriously, I am having some difficulty visualising how a dual point ignition could skip cylinder firings. Does it have two seperate 3 lobe cams with one set of points for each cam with one condensor? One distributor and coil per bank?

 

Somewhere I have a picture, It's pretty simple actually. The points are across from each other (180 degrees apart) the same cam works them both alternately. Both sets trigger the same coil.

I suppose it is possible to set them in the car with a timing light if you have a helper and really need to do it the hard way.

The tricky one is the 12 cylinder distributor with 4 sets of points.

 

File, dont sand. Sand paper and emery cloth can leave conductive deposits. Pick up a point file, its really the proper tool. But so often the points do not align thier faces squarely, but are almost always in some manner of misalignment. It can be beneficial to carefully bend them so as they come squarely together on thier face. Leaving the ignition on will burn the points up, and can even overheat and pop the coil. Just depends if any points are closed. With 12 cylinders and four points sets its pretty near impossible for one set not to be closed somewhere.

 

Ferrari used both Lucas and Bosch distributors on a few cars. The Lucas distributor is very similar to those used on Jaguar D-types and Aston Martin race cars.
Be very careful with your distributor caps and rotors as they are made of unobtainium.