123 Distributor
 

I posted this on the 140 group but haven't had any replies yet.
I have inherited a 123 distributor(switchable) on my 145 but have no experience of them before. On inspection it seems to have a lot of free rotational play, some between the rotor arm and shaft, and some between the aluminium disc that holds the magnets and the shaft. Combined I would say about 5 degrees or more, and not sprung so it's just 'slop'. The aluminium disc is a very loose and sloppy fit on the shaft and there seems no way of tightening it. So my question is, can anyone with experience of these distributors confirm if this 'normal' or not please.

I have one on my 140 and the alu' disc does seem "sloppy" As long as the "slop" is only rotational,that's the way it's meant to be, it should be OK what you don't want is too much "slop" at the shaft where it engages with the cam. Are the dogs worn? they are not central but slightly offset from the center line.Hold the top of the shaft,where the rotor arm fits and the bottom of the shaft where it engages the drive and wiggle it in the body to see if there is play.

Thanks for that input, 'dogs' seem fine. Not sure what you mean with regard to the cam, obviously no points so no cam lobes on the shaft. I would expect that much movement to oscillate under some conditions and have some effect on timing. There doesn't seem to be any reason why it needs to be designed to have so much free movement.

Are you talking about the resin rotor in the 'spark distributor' portion of the distributor? Normally that would be a very tight fit on the distributor shaft. Be aware that there have been problems with the Bosch and Behru rotors used in the 123 distributors. I don't know whether these problems are specific to the 123 distributors or common to all distributors using theses rotors.

Some (all?) of these rotors have a resistor embedded in the rotor connected between the center contact and the moving contact. The purpose or the resistor is to help suppress electromagnetic interference (EMI). There have been reports of this resistor failing in a catastrophic manner which in the best case just results in the engine stopping. Carefully examine your rotor for damage and try to determine why the rotor is a loose fit. My recollection of the original Bosch distributor on my B20 ewas that there was a spring clip inside the rotor that made it a pretty tight fit on the shaft. Definitely no play.

I think the slop that Arcturus is referring to is the clearance between the drive gear on the camshaft and the gear on the end of the distributor shaft.

Ask Rob? Presumably he fitted it?

More accurately, I should have said where the fixture on the end of the distributor shaft engages the offset slot on the oil pump drive gear.

142Guy; All the play I'm referring to was established with the distributor removed from the engine. It's a combination of play between the rotor arm and shaft, and between the aluminium disc and the shaft. There is no name on the rotor arm but the cap is a Berhu.
Morwenna240; I think this was fitted by the owner before Rob.

Umm. In that case i'd incline towards taking a little video of you waggling the shaft an send it to the 123 guys and ask their esteemed opinion.

I'd be interested to know about 123's longevity/quality control as am thinking of fitting one to my 145 an poss PV.

M240 yes I might do that but thought knowing how many people on here have fitted them I wanted to establish if these 'symptoms' are typical of these distributors even when new. But having said that it made me think, how many people consider them to be 'plug and play' or 'fit and forget'? Never bothering to look inside again.

I've had mine in and out dozens of times to change curves (it's an older model) but i can't answer your question re play as I have never looked for it. All I know is that my 123 has been 100% reliable since the day I fitted it over 8 years ago, and the car has been used every day since. It is a 5 minute job to put in/out, so maybe whack it in and see if it's working to your liking.