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Just redone head gasket with Minispares own copper jobby, torqued down carefully and hopefully correctly, now what’s the next step? Run motor for 2-3 minutes heat cycles with empty cooling system?

No, dont do that. Put coolant in the engine and start it up and keep it going for a minute. Then switch it off and let the small amount of heat cure the gasket "biscuit". Once cold , start it up and bring it to full temperature, then check for leaks. Running it dry mat cause warping and cracking

My preference is:
Run it dry for 30 seconds to activate the pre applied sealant
Let it cool
Fill with plain water
Start it up and run it properly to check for leaks and give it a heat cycle
Remove the radiator cap to ensure there’s no coolant pressure
Retorque the head
Once you’re happy it’s all sealed then drain the water and refill with coolant

Coolant is very “thin” and will take any chance to creep between the block/head and the gasket. Also if you find a drastic leak you don’t spill coolant across the floor, it’s only water

If you've put sealant on the head gasket, you're kinda on your own here;-

http://mk1-forum.net/viewtopic.php?f=3&t=38887

unless swifty can give you some guidance.

There will be lots of different views on this .i don’t think you can beat wellseal… Shirley

Might be a silly question but. Did you adjust the valves before starting it up. ?

Modern copper gaskets have a much lower copper content than older ones , my opinion is that they are a total waste of time and money, had two experiences of failure in the first 1000 miles. Just got a composite one.

Rusty old S wrote: ↑Wed Jun 19, 2024 5:48 pm Modern copper gaskets have a much lower copper content than older ones , my opinion is that they are a total waste of time and money, had two experiences of failure in the first 1000 miles. Just got a composite one.

The original copper composite head gaskets that many of us found so good in the past had a fair bit of asbestos content in the filler material. That today of course is all gone. What ever it is they use isn't nearly as good at resisting heat as asbestos was and also today's fuels burn hotter, so the modern versions can burn through much easier than those of days gone by. On a fresh engine build, if everything is prepared well, new fasteners etc, the new versions can work exceedingly well, but using one as a replacement, as you found, can be fraught with issues.

Yes, valve adjustment is spot on as per BMC manual

Just seen a you tube video on swiftune interviewing nick swift . What caught my eye was a mechanic in the background holding a tube of Wellseal . Just saying ! …. Shirley

It depends on what type of head gasket you are using will determine if you use sealer or not.

The copper gaskets always needed sealent. Some of them came with it pre installed. Most of them are made in India out of very poor quality materials these days and are not worth using.

Payen and Victor Rinze gaskets require no sealent, they are made well.
The BK450 turbo gasket with the rubberised coating can also be fitted dry, along with the Rover green gaskets.
A MLS Cometic gasket requires no sealent.

In Australia the preferred sealent used by the motor industry is Hylomar. It is available in spray cans.

Install the gasket, torque correctly, adjust tappets, fill the cooling system and drive. Retorque and adjust as required while hot. That's all you need to do.