Technical Fiat 600 distributor issue

[skateman]

Just finishing up restoring my 1960 Fiat 600 and encountered an issue with the ignition timing. Set cylinder # 1 at TDC at the end of the compression stroke then set the distributor rotor pointing at cylinder # 1 and clamped the distributor support after engaging the shaft gear. Now, at that configuration, the points are touching the flat area of the cam on the shaft and even with the play you have with the vacuum advance plate hole it would be outside the range to get to the points just opening (touching the heel of one of the four loves) where you need to be at that stage.
Is there any way to change further the relative location of the shaft body and points?
One way would be, for instance, to rotate the top part of the shaft (which encapsulates the felt piece) relative to the shaft if possible at all.
Any inputs are appreciated!

 

[bugsymike]

Just finishing up restoring my 1960 Fiat 600 and encountered an issue with the ignition timing. Set cylinder # 1 at TDC at the end of the compression stroke then set the distributor rotor pointing at cylinder # 1 and clamped the distributor support after engaging the shaft gear. Now, at that configuration, the points are touching the flat area of the cam on the shaft and even with the play you have with the vacuum advance plate hole it would be outside the range to get to the points just opening (touching the heel of one of the four loves) where you need to be at that stage.
Is there any way to change further the relative location of the shaft body and points?
One way would be, for instance, to rotate the top part of the shaft (which encapsulates the felt piece) relative to the shaft if possible at all.
Any inputs are appreciated!

Purely from a mechanical point of view and no recent specific Fiat 600 knowledge, as the last 600 I owned with suicide doors etc. was in 1972 approx.
Assuming it is all the original parts and distributor has an offset dog drive then I suspect when oil pump was out the gear drive was assembled out of line, so sump off and reposition oil pump for gear to match distributor correct alignment is required.
I am sure someone here on Forum will be able to guide you with exact method of alignment.

 

[skateman]

Purely from a mechanical point of view and no recent specific Fiat 600 knowledge, as the last 600 I owned with suicide doors etc. was in 1972 approx.
Assuming it is all the original parts and distributor has an offset dog drive then I suspect when oil pump was out the gear drive was assembled out of line, so sump off and reposition oil pump for gear to match distributor correct alignment is required.
I am sure someone here on Forum will be able to guide you with exact method of alignment.
View attachment 440293

GM and thanks for your response!
The issue I have has nothing to do with the adjustment of the distributor to the engine itself but the relative position of the distributor cam lobes relative to the location of the top part of the dis shaft which dictates the position of the rotor.

 

[bugsymike]

GM and thanks for your response!
The issue I have has nothing to do with the adjustment of the distributor to the engine itself but the relative position of the distributor cam lobes relative to the location of the top part of the dis shaft which dictates the position of the rotor.

Sorry, I thought you couldn't swing distributor around enough to get the points to be just opening on No 1. in which case moving the HT lead position in the cap for No 1 may have helped.
Do you mean when points just opening rotor doesn't sit by an HT point in cap ? That does sound strange, is the distributor original and was vehicle running prior to rebuild?
The balance weights under the contact points plate haven't been moved out of position?

 

[skateman]

Sorry, I thought you couldn't swing distributor around enough to get the points to be just opening on No 1. in which case moving the HT lead position in the cap for No 1 may have helped.
Do you mean when points just opening rotor doesn't sit by an HT point in cap ? That does sound strange, is the distributor original and was vehicle running prior to rebuild?
The balance weights under the contact points plate haven't been moved out of position?

Yes, yes and yes.
The weights were intact.
For clarity, I’m reattaching the picture showing the two parts that I wish I could rotate relative to each other to solve the issue. Thx!

 

[bugsymike]

Yes, yes and yes.
The weights were intact.
For clarity, I’m reattaching the picture showing the two parts that I wish I could rotate relative to each other to solve the issue. Thx!

Is there any chance the mechanical advance and retard side is stuck on the shaft, preventing it from moving freely.
Where the felt is on the end on the old Lucas distributors when servicing I always put a few drops of engine oil down there and worked the rotor to check the advance weights were moving correctly. On those there was a small screw which could be undone to release the mechanism.
By turning the rotor you could see the bob weights move allowing mechanical advance, if no movement it is probably seized.

 

[skateman]

Thanks my friend.
I was able to improve positioning by a little bit but it would run rough at the edge of the advance verge. I’ll try to get a new shaft/ distributor in the future.
Thx!

 

[bugsymike]

Thanks my friend.
I was able to improve positioning by a little bit but it would run rough at the edge of the advance verge. I’ll try to get a new shaft/ distributor in the future.
Thx!

If it is just seized, cleaning and oiling may be all it needs. You have to be careful of the little advance and retard springs on the bob weights.
Also some may look loose as in free play before they start to operate, but this is correct.
If yours is similar in design to this, undoing the screw in centre (usually under the oiling felt, then carefully unhooking the two bob weight springs, if not seized it should slide up and off the shaft. When refitting take care to locate the bobweights that control the advance(usually into little spigots). I tend to think if the original can be repaired , it will be better than a modern low quality pattern part personally.