better in the rain

[Dave Mann]

I suspect the higher temperature helps with the mixture, soon after the trip from Falmouth I was on a local dual carriageway one cool evening and the best I achieved was 45mph flat out.

[Graham Barker]

A club member in Auckland inherited a recently restored Ruby and was very disappointed with its performance compared with my Ruby. We found that the difference was caused by his throttle spindle not opening fully!
Graham.

[Bob Culver]

Water injection is primarily to forestall pinging. it would reduce inlet temp and hence increase weight of air and oxygen but significant mainly  when pressure charged.
Hot days and running thins the oils which makes a big difference.
Decades ago when my car was everydayrtransport my commute home involved a steady climb. With the lubricants warm, the RP was notably better in cold conditions. (The improvemnt seems better that the air density differences suggest. The manifold remains colder which gives a bigger difference then the outside temp indicates)

[Duncan Grimmond]

My lack of speed of some months back was eventually self-diagnosed as operator malfunction. I hadn’t noticed that the “locked-off” choke lever had slipped into partially functioning position.
As to cool humid air effects I have neither experience nor solution. Altitude variation in the Pyrenees has been so short-lived that I decided not to bother making adjustments. However if I was planning a longer trip in high altitude I’d adjust my mixture slightly.

[john williams]

On one of our N Wales weekends a few years ago, one of our members in a MkI ruby had great difficulty keeping up with the convoy. cruising 40-45 mph.
At Aberystwyth, he changed the head gasket, still no improvement. On arrival at LLandudno, there was a "Committee" inspection of the car. The only fault we could find was a seized distributor advance spindle. Loaned him the spare distributor I was carrying, and the car's performance was transformed. I would never have credited the improvement, and fitted the returned distributor to my RL to replace the original manual advance unit.

[andrew34ruby]

Your top speed, as quoted above, is low Andrew. 

The car should sit comfortably at 40-45 mph, even in your neck of the woods.

I had quoted it was not happy to pull beyond 37. So this morning I tried to sit comfortably at 40 to 45 on the flat. Yes it's comfortable at 40. It reached 46 fairly soon after. Then I ran out of road and had to slow down. In the past I have had it to 49. All these speeds measured via satellites.

Today is warmer, 18 degrees, and not raining, but quite moist after rain a few hours ago.

The weather does seem to make a difference, but worst might be a very hot day, in traffic, with all the bonnet vents closed. It doesn't overheat, but maybe the underbonnet temperature affects the air going in.

Another problem might be me not liking to thrash it.

[Reckless Rat]

With a recently run in engine I gave my RP its head on a long flat road in Spain. It achieved 92kph on the GPS which I think is 57mph. Not bad seeing that Austin said the max speed was 48mph. I backed off very quickly afterwards in case it self-destructed. 40-45mph is a good cruise.

[Ian McGowan]

In my experience, the factor most responsible for varying the "rate of going" is head wind/no wind/tail wind. Hardly surprising for cars with aerodynamics similar to a breeze block!

[Malcolm Parker]

When I had my 1923 Fiat 501 the handbook didn't mention top speed, it referred to 'terminal velocity'!

[Renaud]

No experience with A7 but when I had my other Austin (mini 850) in the beginning of the seventies I had a very sensible boost when the air was moist (which it can be in Brittany). Since I know I will experiment with water injection one day. (Yes I know...)