It sounds like tracking, if you run low profile tyres you will get one sits in the wheel tracks and wants to get out, the the other wheel gets into the track and so on. See if the problem is still there when you change wheel size

7x13 wheels and others with lots of offset are prone to `tram tracking' or following features in the road. This is due mostly to the fact they have positive scrub radius (centre of tyre is well outside the ball joints' pivot axis). This promotes unstable steering, particularly if one wheel has better traction than the other due to the surface (eg if you hit the gravel).
Some modern cars (eg VW Golf) promote the fact they have negative scrub radius for steering stability.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Not enough Toe OUT. You're probably running at zero or toe IN. Being big wheels you'll need more than what the book says.

_________________

Update -
I had a look at the wheels, camber appears to be dead straight, if not then slightly in.
All engine mounts are ok, except top one which looks a tad worn (no movement if you try and shake engine by hand).

Booked in for a proper alignment elsewhere, just to be certain.

BUT...
I think the rack is rooted.

There is a clunking from the rack where the pinion goes in when you turn wobble / turn the wheel in each direction quickly while stationary. The column does not move on the splines, it is a solid tight grip. The clunk is coming from the rack itself.

Also, ff I turn the wheel left, the floor is pushed out towards the engine bay, if I turn right it is pulled in. I do not remember the floor ever flexing in any other Mini when turning the wheel. It's parked up until that clunk is resolved or rack is replaced.

Sounds like you need another DrMini rack mate.
I have an old one here I can reco if you want.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Yeah, I think I might.

I wasn't sure how to email the last people I bought mine off and ask if their crap racks had improved yet.

Can't go wrong with a DrMini product.

PM me a price Doc and I will organise to pick one up.

If you need it quickly I have a rack that Kev did a few weeks ago. Won't need it for a month or so - so you could use it and get another one organised.

_________________
Dave K.
1979 Moke Californian + 1981 'Coke' Moke