Electric fans

[Charles P]

Thanks so far!
I am running 12 volts.
Mike's point is interesting!
Do many people run standard Austin radiator cores and fans successfully in situations similar to mine?
If so which type of core? Does a standard fan use much power - It was suggested to me that a fan uses at least 5% of engine power.
Reverting back does have attractions!
Steve - why did you use a modern core?

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And Charles - what fan do you use?
My fan is also only manually switched and is never needed on the road.

I cheap one.  Might have been from Car Builder Solutions or EBay. It's about 7 or 8 inches. I'll look tomorrow and see if there's any marking

C

[Steve Jones]

Steve - why did you use a modern core?

My Trials Chummy was a built up car, Bob, made for the job.  Simply, a modern core was cheaper and, I decided, likely to be more efficient. In addition, if damaged, cheaper to repair or replace. I've a similar core on my Ulster that equally works well. I did damage that one such that it needed replacement. I think that cost around £120. Pattern core would have been rather more! 

Steve

[Nick Salmon]

I have exactly the same issue as Keith - and funnily enough it was at Cobham Trial it showed itself. On my Special whoever designed it placed the rad so far forward of the fan as to render it all but useless. 

It had not been a problem for years of normal road use, but when we started trialling some time ago we did find the engine was overheating and losing power. So I took the fan off and fitted a switchable electric fan - about 9" I think. We tried it out at Westerham last year but it failed failry quickly (buy cheap, buy twice) so I obtained a 10" replacement.

First time of using it in anger was Cobham last weekend and it performed really well - being switched on and off as required. However, I could see on the ammeter it was taking quite a bit of current (the car is 12 volts with an RB106 and the original three brush dynamo), maybe a negative 3-5 amp. By the end of the day the battery was very tired, though in fairness it probably was not fully charged to begin with.

I shall give it another go in due course.

[Malcolm Parker]

I have used standard and modern film cores on many sevens over the years and have never had any problems with overheating.   My experience of Austin 7's that overheat is that there is usually an underlying problem of carburation, timing, type of fuel etc.  The standard thermo-syphon system appears to work well on the vast majority of trials Austin 7's.  If the car is going up a 30 degree gradient it should work even better!
The only time my saloon has ever overheated was when I was using cheap supermarket unleaded petrol.
I can vouch for Steve's trial car, generally the problem was getting the engine warm enough.   I have always run with the standard 2 blade fan with the fan belt quite slack.