Morris Minor Owners Club

Hello again. I am putting a mk3 1967 1275 MG Midget engine into my 1971 Morris Traveller - I have got the Distribution Doctor to do me a new Distributor 25D4. I wonder will I need a side cap or top cap and presumably a new set of leads - I was thinking Magnicor 7mm?

Any advise appreciated.

Paul

Unless, someone knows different, I’d say it’s a matter of choice, I think a side entry would be neater. New distributor, new leads !

When I had the D.D. rebuild (25D4) it was returned with the correct top for year, distributor and relevant to the information I provided him. i.e. side entry.
Possibly your distributor will be returned dependng on the information you supplied?
I personally do prefer the side entry although changing/fitting the h.t. leads is a bit more involved at the distributor end.
Without checking and if my memory is correct, the D.D. side entry cap is limited to 6mm diameter h.t. leads.

I think it varies by year, side entry is earlier, but I am not sure of the changeover year.

If you make up your own HT leads, as I do, side entry is quicker to make up a set and the result is neater in the engine bay.

With a top entry HT lead set you need to crimp on connectors to make the proper push fit with the distributor. With a side entry you just cut the HT lead square, insert into the distributor and clamp down the screw which drives a spike into the cable. At the spark plug end of the HT cables you can use resistive suppressor caps that just screw on so no crimping required at all.

I use copper core HT cable which last a very long time in service. It is NOT suitable for all ignition systems. For instance, copper cored cable is not recommended with some electronic ignition systems.

One issue with side entry is it is a bit more confusing as to which HT cable is the next one in the anticlockwise firing order sequence 1,3,4,2. It is easiest to label the leads. The other issue is that there are no rubber HT lead boots at the distributor end so possibly they are more prone to water ingress.


Stephen

You are exactly right - just rechecked packaging and the cap (side entry) was in the bubble wrap. Thanks for that.

Out of interest, just how long should HT leads last?

Does it depend on age, or amount of use - and how can I tell if my leads are degrading in performance even if they look in good condition? Is there a simple test that can be done?

My car has electronic ignition - this was fitted 9 years ago, alongside a new set of leads. The car has covered 14,000 miles in that time.

Thank you!

The life of the ignition leads are dependent upon what they are made from.
The best in my honest opinion are the old copper cored ones as they seem to last for ever.
I have 'Splitfire' twin core 8mm leads fitted to my engine and they have never given any trouble over many years. They are used with a Lumenition high performance coil.

Thanks Phil, that's good to know!

Pete Bags wrote: ↑Fri Jan 09, 2026 2:58 pm Thanks Phil, that's good to know!

But note that 8mm OD HT cable may not fit in a side-entry distributor cap. 7mm definitely does as that is what I use.

https://www.gsparkplug.com/electrical/i ... opper-core

Stephen