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MG MGA - Fitting a new distributor

I am in the process of fitting a new distributor, but have a couple of questions please.

Firstly, the connection to the vacuum control unit on the new unit is a simple push-fit, whereas the old one was a screw-on connector (see photo). Can I simply use a length of flexible hose to join the metal pipe to the new unit, or does it have to be something more substantial?

And secondly, the distributor cam on the old unit spins freely, whereas the new one requires a lot of effort to turn it. Does it need to be lubricated before I install it, or does it pick up its own lubrication from the engine when it's up and running?


Robert Sinclair

I recently fitted the 123 distributor with the push fit vacuum connection - I just used a rubber flexible to connect to the copper vac pipe.Even my new distributor was very easy to turn I dont recall it being stiff
P D Camp

Thanks Paul. It's good to know that a rubber sleeve will do the job, but I'm worried about fitting the new unit when the central cam isn't spinning freely. I've lightly greased it, and it's certainly better than it was, but it still needs firm pressure with two fingers to turn, whereas the old one spins like a top! Will it improve after use, in situ, or could it damage the drive spindle?
Robert Sinclair

Take care that your rubber sleeve is reasonably thick or it might collapse in the 'vacuum'. There is a special rubber connector in the Moss catalogue, I think, which is pretty thick.............Mike
m.j. moore

At least it makes for easy disconnection when doing dynamic timing. I just use a couple of inches of clear plastic piping from the local hardware shop. Been ok for the last 16 years.

Steve Gyles

Ok, maybe I went a bit over the top, but I cut a piece off a bolt (its a standard UNF thread 5/16" if I remember) after running a drill down the centre same diameter as the vac connector. I cut the vac connector down and bonded the threaded section over the top. Sounds like more work than it was, but I can use the standard pipe fitting and keep it looking original.

I used an electronic distributor available in a DM2 type body and moved the connection point so there is only one lead to the coil. So it all looks pretty standard.

The shaft was smooth and free to turn BTW.

Ooops! just realised from your picture you have a different vac type anyway, so my pedantic efforts would be a waste of time...
N McGurk

Difficulty turning the cam is a red flag. Something is binding. Who supplied the "new" distributor? I think I'd be talking with them.
Clear plastic tubing should be OK. As long as the copper vac pipe is reasonably secure from movement. If there's a lot of movement in the vac pipe after fitment (vibration, etc) you probably won't have a leak free connection for very long.
JM Morris

Moss Motors sells a simple little slip on adapter to connect the stock (threaded) vacuum line to the dist. the part number is 153-840.
Keith Lowman

This thread was discussed between 24/10/2012 and 25/10/2012

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