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I replaced the ignition parts today to sort a misfire.

Took the car to get petrol. Filled it up. The car wouldn't start. Lifted the bonnet and all the leads were roasting hot. Let the engine cool down. Then it started. Same happened again when I stopped. Cool down and all ok

My temp gauge stopped working again today so no idea how hot it is.

Is it just the weather,? Its in the 20s.

How can I tell if the viscous fan is broken?

They normally become 'loose', if you grip the blades and try to waggle the fan you can feel any play. They sometimes get noisy too. If there is play it is best to replace (I replaced with an electric one in front of the rad and the viscous hub is still on the car, just removed the fan). If it lets go the fan blades tend to try and get out through the rad and the bonnet, makes a mess.

It sounds like your problem was ignition, & your are now burning all the fuel producing more heat, rather than some of it going through unburned, producing no heat & taking some of the heat with it out the exhaust pipe.

In good condition 7s do not have an overheating problem. Mine is producing near the high end of a standard 7s power. It can run through our 35 C days driven hard, or in stop start traffic, running the air conditioning, & never get above 3/8 on the gauge. With m gauge that is the water coming out of the engine at 91c.

I suggest you get an infrared temperature gun, & FIND OUT what temperature yours runs at. They are only about A$20, & you will then know what your car is doing.

When I bought it mine was getting a bit hot, with no aircon. I found it had about 30% of the radiator blocked, with no coolant flow at all, when tested with the infrared gun. The sections of the radiator at & after these blockages was 40C cooler than the rest when running.

If you can't afford that IR gun right now, drive the car, stop & stop the motor, then run your hands over the radiator immediately before the heat spreads. It won't tell you as much as a IR gun, but enough to know if your radiator is partially blocked or not.

I fitted a new stock radiator, & a new thermo fan, when the aircon was fitted. It has never overheated. In retrospect I think I wasted my money on the fan. A friend grabbed my old one in an emergency, when his had it's bearings start to collapse. The thing is still cooling his car perfectly 3 years later.

On the other side, my 8 had a cooling problem for quite a while. It is computer controlled injected. We ultimately found it was tuned too lean at low revs, small throttle openings. Once we richened the mixture in that low speed area, all overheating disappeared. This is not likely on carbs, unless some previous owner has fitted the wrong mixture needles. Not likely, but stranger things have happened with some POs.

Hasbeen

Viscous fans normally don't "break", the bearings give out, usually creating noise. With motor stopped, turn the fan blade. It should be smooth turning with some resistance. If bearings are bad you should be able to feel it. The viscous fan will keep the car running cool, mine runs at just over 1/4 gauge regardless of conditions with a needle width or so separating cool ambient temp to mid 80's (rarely gets hotter than that here) in stop and go driving.

While any new high tension wires will work (for a while) I use Magnecor metal wound wires custom made for FI TR7's. Don't deteriorate, low resistance, high impedance.

I'll source a thermo thingy today and give it a go.

I do feel I've made progress. The car was pulling better and for a few short minutes was fun!!

I have had it happen many times on a hot day. Normally at the petrol station, it will start though, after turning over for about a full minute .....

I think the heat sink from the engine makes the petrol evaporate, so it just has to pump through again by turning it over for a quite a bit.

I have taken the stat out for a while, and the starting issue is gone for the time being, but now it takes rather too long to warm up !!.

By the way, have you cleaned your plugs yet or changed them ?

I fitted a new battery yesterday to the 7. The old one was starting the car OK, just, but was only holding a charge for a couple of weeks, when not used.

This caught me out a couple of times when I forgot how long it had been since I used the car. It was 4 & 1/2 years old, but had only done about 6000 kilometres. Shame on me.

It is amazing how we get used to things. With the new battery the starting is almost instantaneous, rather than winding over for a while before firing. I'd forgotten how well the car starts with enough electrical oomph , & how nice it is to have it that way.

Hasbeen

I stuck all the ignition parts in one at a time and swapped out again to check the misfire. I need to put the new plugs, cap and rotor arm back on. The car is definitely pulling better

My mechanic mate is back from holiday today so hopefully get round this week

I have taken the stat out for a while, and the starting issue is gone for the time being, but now it takes rather too long to warm up !!.

Running a TR7 engine without a thermostat is not a good idea due to the foot valve not being there to shut the bypass.

Assuming you have the correct thermostat in in the first place. Suppliers carry both and you might get/have the wrong one.

I took out a 74 degrees stat without the foot plate - I checked with Robsport who supplied it, and they were adamant that the footless stats they supply are fine for the job. They have fitted and supplied them for many years without issue......?

Without a thermostat, other than taking a long time to warm up, and therefor needing choke on for longer, there is no issue with the cooling ? I only took it out, because when the engine is fully hot my timing chain rattles very slightly, whereas it is silent when the engine is very warm, and I will try anything to avoid the obvious requirement of getting it repaired (ahem)

Can't remember if I got my footless thermostat from Robsport or S&S but I had them send me one with a foot. My original one had a foot. With out the foot only part of the coolant goes through the rad, it's like having a partly blocked radiator. Fine if the ambient temp is cooler and you are cruising down country roads or empty highways but if the weather temp soars and you are driving in stop and go driving in a city traffic jam, you may need all the cooling that the car design provides (and as Hasbeen states, it does provide enough).

It definately does not get too hot or overheat when sitting in traffic - it is running cooler all round ? I agree though, the foot part would not be there for no reason, it must divert the water flow but why ? I wonder if any other engines have a similar looking thermostat. Why open up and allow more flow around one part of the engine when hot, but block off another channel at the same time - if this is what is happening.....
If all the water can flow everywhere around the engine (i.e no thermostat) then this is providing maximum cooling no ?

I've read on a number of threads that the 7's thermostat foot ensures the coolant is distributed evenly across the engine.

There's this exert from one of Roger William's books stating Use the foot. The same thermostat is used by the Stag and others in the Dolly family. On my RV8 the thermostat is in the intake manifold and no foot required.

https://books.google.co.uk/books?id=soj ... at&f=false