Technical Marelli Distributor Shaft Play

[DanielReid]

How do all,

Hoping some of the experts here can help me out. I've been tinkering with an old 850 I bought for the past few months, just can't seem to get it running perfect. One think I noticed was a (very) excessive amount of up/down play in the distributor shaft when installed on the engine - nearly 1/4". Surely this can't be right. It's a Marelli S140 Distributor. Measuring with my vernier, the rotor seems to touch the centre of the electrodes in the cap when the shaft is pulled up toward the top of its travel, but of course it's natural tendency is to fall down below this position.

Any thoughts as to what might be wrong? I've taken apart the distributor, cleaned it up, serviced it, and assembled it. Found a few amateur mistakes from a previous owner, but nothing that would eliminate the up/down travel I've got, unless there are some shims missing (which there very well could be).

Any thoughts or suggestions are greatly appreciated!

 

[varesecrazy]

How do all,

Hoping some of the experts here can help me out. I've been tinkering with an old 850 I bought for the past few months, just can't seem to get it running perfect. One think I noticed was a (very) excessive amount of up/down play in the distributor shaft when installed on the engine - nearly 1/4". Surely this can't be right. It's a Marelli S140 Distributor. Measuring with my vernier, the rotor seems to touch the centre of the electrodes in the cap when the shaft is pulled up toward the top of its travel, but of course it's natural tendency is to fall down below this position.

Any thoughts as to what might be wrong? I've taken apart the distributor, cleaned it up, serviced it, and assembled it. Found a few amateur mistakes from a previous owner, but nothing that would eliminate the up/down travel I've got, unless there are some shims missing (which there very well could be).

Any thoughts or suggestions are greatly appreciated!

Hi,
it's a bit too old for my FIAT knowledge..

maybe SEARCH - or ask the question in the classic panda section - as they were still on similar kit..

my 1981 pandas dizzy had the lower part of the splines broken off / missing

it was driving on @2mm of it's original 20mm

Charlie

 

[Jayarr]

Hi,
The vertical play in the main shaft can usually be remedied using shims between the aluminium housing and the roll pin.

 

[F123C]

I can't visualize the 850 distributor right now but iirc many Fiat (Marelli) distributors of that era had a plastic/fibre oil slinger/deflector fitted to the shaft just below aluminum housing/body. Iirc the roll pin passed through this oil slinger to retain it in position and thus set the end-float (up and down) of the distributor shaft. So the order of assembly was al. body on top of shim washer on top of oil slinger/deflector with the roll pin holding everything in place. These oil slingers became very brittle with age and often broke off/crumbled when the distributor was handled when removed from the engine. The absence of the oil slinger iirc increase the end float of the shaft by about 6mm.

So, in brief, OP might usefully check if such an oil slinger disc is missing from his distributor, might explain the excessive distributor endfloat.
If so and this part can't be obtained, a few washers should work fine to correct the endfloat as 'Jayarr' has suggested above.
Hth,

Al.