998, 1098 and 1275S all had the same radiator here in Oz, a 3 core, 16 fins/inch.
It might need a professional cleanout by a rad shop, but shouldn't need `upgrading'.

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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.

I pulled out a 1275 put the same one back in. Used the same radiator as I wS before and it was running fine it was an aluminium one off eBay so I swapped to a two core high flow one that hardly been used from brand new ( borrowed from brother) and still no change.....

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

the radiator was brand new it was a super hi flow 2 core

Good that the lean/ timing /carbie thing is sorted. plus one for getting to the bottom of that. Now onto the overheating. are you sure it is getting hot or is it reading hot. Trying two reasonable to good radiators with the same result either means blockages/ partial blockages within the block/ but not the radiator OR temp gauge or temp sender is just reading incorrectly .
The 82 thermostat will indeed open later but both should be well and truly open before boiling. You can test them by dangling in hot water... you just wont get many bites this way.

What are your symptoms again, losing water?, checked your cap 14 psi (tridon cheap as and everyone has them? checked your hoses aren't collapsing? Again being methodical is the way to nail it.

Check if really is too hot or just a sender /gauge issue
Check if rad cap is holding pressure ( that is where you raise the boiling point of your fluid to 114 .. so not holding pressure can steam away early.
Visual check hoses and squeeze them
Run lots of water through the block from both directions. may even pay to get a scourer agent ( some people like them some think they can loosen up more flakes and cause blockages
radiator tested pressure and rodded as dr said can work wonders. Hope you solve this soon

Thanks for your reply FNQ cooling system is holding pressure. I have a manual gauge that seems to wrk fine when it reads about 100 degrees I turn my car off n I can hear my rad makin noises n sometimes a bit of water will spill out the overflow ... Especially if I've just filled it up, water is circulating as all hoses are hot so is the top n bottom of radiator. Did flush cooling system a few days ago and was pretty dirty but seems to be pretty clean now. I did check the thermostat in a cup of hot water and it did opens then when I pulled it out she closed after a while when it cooked down enough. Thanks again for your help. I'm not loosing water either once it squirts a bit out after refilling it stays ay the one level.

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

My topics seemed to have gone quiet for some reason but I have a Question. I was thinking I bout a fuel pump off eBay. it is suppose to pump 1.5 to 3 psi. If this pump isn't pumping enough petrol say cause it's cheap Chinese rubbish? Could this be my issue for my over heating?

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

hi again

although a bit hotter than ideal , it would be worth seeing if your system stabilises at 100 ish.....remembering that it won't boil till about 114. and also there may be a little variation in temp gauge. .. but if you don't want to cook it or take the chance then give that a miss. A simple aux radiator running off the back head outlet but plumbed to the front of the car right behind the grille, picks up all the cooling wind... i used it for a while but sometimes it wouldn't get hot enough,,(nearer 70 than80) so took it off..... the extra water volume and the extra cooling works wonders..... i think i used a commodore heater matrix... just ask around some are peculiar in wanting to be plumbed a certain way, i just used a bit of alum bar bent to shape and those u type nuts )

your pump volume /pressure shouldn't be problematic but could be an issue but normally if you turn on the fuel pump and see fuel filling???? a cup etc pretty quickly then it should be supplying plenty of fuel it only needs to supply say 10 litres an hour not 10 litres a second

Ok well my brother has a four core radiator and beats me to try that in my vet and see howbit runs. Also has a Thermo fan I could try and hook that up? It's blowing smoke on start up now also. Any ideas what this could be?

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

Generally smoke on start up is valve stem seals. Once everything warms up to temp the clearances get tighter and they start to seal.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

The head was rebuilt hardly done any wrk I'd say under 1000km but has been very hot

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

hoping not to be the case , but as 1018 said valve stem seals, maybe they gave up a little after having the blow by from the bore glazing ?
i have just learnt that sometimes the oil feed going to the rockers can oversupply the rockers and the excess can migrate to valve stem seals, or

a number of the better informed mini engine builders have said minis don't take too well to just a rehone, it could be the new ring/bore interface allowing a tiny amount of oil through until warm and expand? but most likely valve stem seals. again although only 1000km maybe the extra heat deformed them..,, pity whilst not a big job it means another head geaket

Do you think it would be wise to put another 1275 head on? One that I knows In good working order?

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

I've pulled my head off and one of the exhaust I think valves is black. The other three are a different colour. Also between 2 and 3 cylinders on the head gasket is black but not blown through. Does this mean it was still leaking?

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland