Running Temperature

[Mark]

Please can someone tell me the optimum running temperature of an ARR Ruby? 
I have heard so many discussions on overheating and boiling on long climbs or in traffic. 
 
I am not experiencing any overheating problems myself, and in fact believe the engine to be running on the cold side, as I rigged up a temporary capillary gauge and only seemed to reach 40-45 degrees Celsius, even on a long climb, going up to 70 degrees stationary in traffic. 
I have a standard 2 bladed fan and radiator.
 
With the recent discussion on fuel economy I was wondering what affect this was having.

[Chris KC]

I've certainly experienced boiling but only under alpine conditions, shouldn't trouble you much in the UK.

One thing to keep in mind is that water temperature and oil temperature are two entirely different things. It's important that the oil reaches a healthy working temperature and the engine mustn't be caned before it does.

[bob46320]

We were out yesterday Rn saloon, 4 blade fan, front tank, new modern core radiator:-
Fuel tank 53 deg C
Carburettor 50 deg C
inlet Manifold 72 deg C
Radiator top 77 deg C
Ambient Air 33 deg C (SW France)

its interesting that under similar conditions a few weeks ago, that we suffered from fuel vapourisation. Changed expansion loop in the fuel pipe from vertical to horizontal seems to have helped.

[Steve kay]

Out in the Ruby yesterday, rumbling up the M50 toward Prescott reading just above 80 degrees. On the Cotswold Rally going up to about 86 going up steep hills in second, quickly dropping down to 65 going down the other side. Only two of the four bonnet side louvres open. This is a newish engine and recored radiator, and so confirms what has been mentioned on the forum, when the machine is in good condition temperatures might stay a bit low. After recent mpg discussion, I reckon that 45mph cruising, with no vigorous wind, gives about 40 mpg and slowly going up and down Gloucestershire  hills is no worse. Deciding to come home gently is a lot more economical,  still air and cruising at 40 mpg gave closer to the magic 45 mpg. These are estimates on observations rather than scrupulous scientific measurements, but  they confirm that such a small engine is very sensitive to changes, three up into a vigorous Westerly uses much more than a single crew member coming home gently on a still summer's evening.

[Colin Morgan]

It is interesting to see what others say about normal running temperatures.  The history of my Ruby and a date plate suggest that the radiator was last re-cored in 1957, so is no longer in its prime.  The core is the type with folded horizontal fins between vertical tubes (as shown in Fig 6, on p71 of the 'Companion').  I think this design is more efficient than the original?  The engine has always run on the hot side but has never boiled.  A few years ago I put a temporary thermocouple in the top of the radiator to see what temperature it was reaching and found it peaked at about 90 C on the typical runs I do around here - it is relatively flat.  Then, last week, as part of the investigation into air deflectors, I fitted the thermocouple again and found the engine was now running at up to 95 degrees on a warm summer evening.  So, whilst it is not boiling yet, the temperature is rising, and this seems a bit hot?  

[However, just remembered that I need to bear in mind that when an engine is running hot it is not always caused by poor cooling - it can be mechanical (binding brakes, low tyre pressures, etc), ignition (wrong timing, dirty plugs, etc), carburation (air leak on inlet side, etc), or poor compression, engine in need of decoking etc. If there is a boiling sound when the engine is first turned off, this suggests that the radiator was coping but there were pockets of localised boiling in the engine itself. Such an engine will probably smell hot.]

Colin

Update: Changed the radiator to another used one - now runs at 80 degrees maximum (with a 17 degree ambiant), which is more comfortable.

[Peter Naulls]

When we inherited our Ruby a few years ago it was fitted with a temperature sensor in the top hose. With a newish radiator, 4-blade fan and rebuilt (but run-in) engine it would show anything between 85 degrees and just short of boiling point. The ambient temperature seemed the most important factor. It never actually seemed to boil and in the end I removed the gauge and sensor - partly because the gauge rattled horribly and partly to stop me worrying about it! I also wondered if the sensor, which was fitted into a heavy gauge sleeve pipe in the hose was impeding the flow of water.

Your scientific approach to the baffles is appreciated Colin - I have now called off my long-standing search for a lower baffle.

Peter.

[Hedd_Jones]

My chummy runs on the 'A' of Normal on the Wilmott Breeden calorimiter. The RP (4 bladed fan). Runs on the 'M'. The grey box has a Boyce Motormeter (terrible thing), it runs between a 1/3 and 1/2 up the tube

[Colin Reed]

A lot of times it is not getting air in but removing it from the engine bay as the Air flow stalls, hot air gets trapped above the Engine where there is no place to exit .
If you remove the bonnet and run a temperature test I would be very surprised if Temp did not drop.
Not just Sevens that this happens with.

Colin
NZ

[Bob Culver]

As long as the engine is submerged boiling is unlikely to be damaging.
The main threat is probably to the core if the overflow pipe is not of  adequate diameter. Because of the loss of water due sloshing, often been pinched near closed.
From the days of the Model T the folklore is that retarded spark causes overheating. But from experience with other makes  excessive advance very often the factor. (not so likely with harsh Sevens).
At higher cyl temps cyl wear to all intents ceases. Even the humble Bradford, with no fan, and very prone to boil, was fitted with a thermostat.

[Mark McKibbin]

You probably need to check if your temperature measurer is accurate as I have just replaced my gauge with a more period correct one and now I'm running 10 Degrees C hotter so I need to put the sender into a pot of boiling water and see what it says.