1972 Fiat 850, new distributor, won't start

H

Hallbuzz

Low Mileage
I have a 1972 Fiat 850 Spider that is new to me, and running poorly. The spark didn't seem to advance so I bought a brand new, but slightly different. With new:, cap, rotor, points, condenser, mech advance, it seemed like it would remove a lot of potential problems. It was only $90 plus shipping from Slovenia. It arrived today.

I positioned the motor with #1 cylinder at TDC, noted the position of the rotor and removed it.
I inserted the new distributor (with good preset point gap) at what I thought was the same rotor alignment.
The cap, however, points the opposite direction. So I spun it about 180, but that required a few longer wires.
It wouldn't start in various positions.
I then pulled all of the plugs, cleaned and regapped them. Each plug produces a a spark on each wire.

So, all I can think of is I'm off a spline or 2? Does that even matter if the entire distributor can spin to any position (other than lining up the timing mark on the pully and case.)

Pics:
old:
dist_1_old.jpg


dist_2_old.jpg


New:
dist_3_new.jpg


dist_4_new.jpg
 
Unless I'm mistaken weren't the Yugoslav versions of the rear engine fiats all clockwise motors not counter clockwise like the 850
 
I replaced the distrbutor with a known good one in this photo. You need to get the proper Abarth oil cap ;)
20210516_103147.jpg
 
Hallbuzz said:
I have a 1972 Fiat 850 Spider that is new to me, and running poorly. The spark didn't seem to advance so I bought a brand new, but slightly different. With new:, cap, rotor, points, condenser, mech advance, it seemed like it would remove a lot of potential problems. It was only $90 plus shipping from Slovenia. It arrived today.

I positioned the motor with #1 cylinder at TDC, noted the position of the rotor and removed it.
I inserted the new distributor (with good preset point gap) at what I thought was the same rotor alignment.
The cap, however, points the opposite direction. So I spun it about 180, but that required a few longer wires.
It wouldn't start in various positions.
I then pulled all of the plugs, cleaned and regapped them. Each plug produces a a spark on each wire.

So, all I can think of is I'm off a spline or 2? Does that even matter if the entire distributor can spin to any position (other than lining up the timing mark on the pully and case.)

Pics:
old:
dist_1_old.jpg


dist_2_old.jpg


New:
dist_3_new.jpg


dist_4_new.jpg
Click to expand...
It looks like you set the rotor on the new distributor to point in the same direction as the old rotor with respect to the engine instead of with respect to the distributor cap. With the distributor cap on the new distributor being oriented very differently, your timing will be way off. Remove the distributor and rotate the body of the distributor so the cap will be oriented as with the old one, and spin she shaft so the rotor points the way the old one did. Reinstall the distributor in this orientation, and you should be close.
 
Last edited:
ng_randolph said:
It looks like you set the rotor on the new distributor to point in the same direction as the old rotor with respect to the engine instead of with respect to the distributor cap. With the distributor cap on the new distributor being oriented very differently, your timing will be way off. Remove the distributor and rotate the body of the distributor so the cap will be oriented as with the old one, and spin she shaft so the rotor points the way the old one did. Reinstall the distributor in this orientation, and you should be close.
Click to expand...
I tried that initially, but it the cap wouldn't go on without spinning it 180. But I'll try it again.
 
OK, I rotated the dist about 90 degrees instead of 180, and got it running. However, it not great; I still wonder if I am off by a spline.
Now it seems like it's running on 3 cylinders... and the battery is dead (and charging).
 
Hallbuzz said:
OK, I rotated the dist about 90 degrees instead of 180, and got it running. However, it not great; I still wonder if I am off by a spline.
Now it seems like it's running on 3 cylinders... and the battery is dead (and charging).
Click to expand...
There is no such thing as being off by a spline when it comes to ignition timing; the orientation of the rotor with respect to the engine is unimportant. What matters is the orientation of the distributor body with respect to the distributor shaft and rotor. If timing needs to be adjusted, loosen the clamp at the foot of the distributor slightly and rotate the distributor housing with everything in place. Rotate clockwise to retard timing, counterclockwise to advance. If the distributor cap ends up in an awkward orientation when ignition timing is properly set, you may need to remove the distributor, rotate it (without touching the shaft) and reinstall it in a more convenient orientation.

After you get it all running, you need to set ignition timing with a timing light.

One of the gotchas on the SOHC engine is that ignition timing is set using the #4 cylinder rather than #1, but I do not know if this also applies to the 850 engine (100 series?).
 
There is a difference between cam timing and ignition timing.

Cam is typically (using the factory pointers/marks) set on the #4 cylinder.

Ignition timing can be set using either #1 or #4 cylinder. You just have to attach your timing light to one of those ignition wires.

Think about it...
 
Last edited:
ng_randolph said:
There is no such thing as being off by a spline when it comes to ignition timing; the orientation of the rotor with respect to the engine is unimportant. What matters is the orientation of the distributor body with respect to the distributor shaft and rotor. If timing needs to be adjusted, loosen the clamp at the foot of the distributor slightly and rotate the distributor housing with everything in place. Rotate clockwise to retard timing, counterclockwise to advance. If the distributor cap ends up in an awkward orientation when ignition timing is properly set, you may need to remove the distributor, rotate it (without touching the shaft) and reinstall it in a more convenient orientation.

After you get it all running, you need to set ignition timing with a timing light.

One of the gotchas on the SOHC engine is that ignition timing is set using the #4 cylinder rather than #1, but I do not know if this also applies to the 850 engine (100 series?).
Click to expand...
Thank you! The as I thought about it I came to the same conclusion, but it's good to be reassured.
 
MikeHynes said:
There is a difference between cam timing and ignition timing.

Cam is typically (using the factory pointers/marks) set on the #4 cylinder.

Ignition timing can be set using either #1 or #4 cylinder. You just have to attach your timing light to one of those ignition wires.

Think about it...
Click to expand...
When you set the ignition timing with a timing light it does not matter if you clip to the #1 or the #4 spark plug wire. When you are installing a distributor, you don't have that choice; With cam and crank timing marks lined up, the rotor must point to the distributor cap contact for the #4 cylinder for the SOHC engines. I don't know if it is #4 or #1 for the 850 engine.
 
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ng_randolph said:
When you set the ignition timing with a timing light it does not matter if you clip to the #1 or the #4 spark plug wire. When you are installing a distributor, you don't have that choice; With cam and crank timing marks lined up, the rotor must point to the distributor cap contact for the #4 cylinder for the SOHC engines. I don't know if it is #4 or #1 for the 850 engine.
Click to expand...
You do have a choice. You just have to point the rotor to the contact on the cap that corresponds to the cylinder that's just about ready to fire. It doesn't matter which one you choose.
If you line up the marks (TDC and cam pointer), the #4 cylinder is ready to fire.
 
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