Morris Minor Owners Club

Since the threads at the water outlet elbow are anything but what they should be, I think I nead to tap them through, any idea please what taps should I use?

Water outlet elbow ? Do you mean where the heater tap bolts down on the back end of the cylinder head ? If so - these holes are 1/4" unf - so either go up to 5/16", or 8 mm - since metric stuff is more easily obtainable these days. Probably need to run a drill through the elbow fixing holes too.

bear in mind that if you go for a bigger thread the head size will probably foul the heater-tap body.

By elbow I bet you mean the thermostat housing, can you be more specific.

If it's the heater outlet, try longer bolts and not too much tightening. I've stripped a couple of these in the past, and found using longer bolts and just nipping them up enough to stop any leaks has got round the problem nicely

Same probably goes for the stat housing, but I can't remember if I've ever stripped those threads or not - Too many memories of having to saw the alloy off to remember much else about the job...

Too many memories of having to saw the alloy off to remember much else about the job...

A common type of problem mainly through previous owners lack of antifreeze, although I think the brass ones from one of the specialists would resolve the problem.

If it's the threads where the thermostat housing is bolted on - these are 3/8" UNC in the head - virtually the same as 3/8" Whitworth.
And yes, point taken about the bigger heads fouling if it's the heater tap - use Allen cap head screws to get round this problem.

But Roy, would you get an allen key into the one on the left, looking from front of engine, under the outlet. Seem to remember I had to lift the valve as I was unscrewing it to get nut off.
Ian.

Dunno Ian - many different types of valve. There will be a way!

Yes it would be possible with the ealier type gate valve but probably not with the later type valve.