My SS saloon had been driven for decades by two old ladies and no one had thought to change the UK dipping system. Fortunately they were in a country town
You can buy riveting tool abit like a coad chisel but the end is squared off and has a hemispherical depression. Theres a bt of trial and error in how long the rivets should be to peen over neatly I wouldn’t like to try it by myself, balancing spider and blades and hitting the riveting tool
Out of interest, does anyone know why the fan blades are off set and not equally spaced on the fan blade housing?
The uneven (though symmetrical) spacing of the 6 blades was to counter a phenomenon called beating, one of the reasons helicopters are so loud.
You learn something new everyday with the old Jaguars!! Thanks Rob for the information.
The same reason why the old air raid sirens worked. Blowing air through a series of equally spaced holes passing at speed, ‘chops’ the air stream and creates a frequency that varies with the speed of the rotor.
You can impress your grandchildren by facing close to a pedestal fan and talking into it while it is running - your voice will be chopped.
Mind you, I’m not sure that suppressing this minor noise would be noticeable, considering the general noise from these truck engines.
All similar to why tire tread patterns are not symmetrical, to lessen “singing” at speed.
Although SS
fan blades . at least some were equidistant. personally I favour the easier to fit the fanbelt conspiracy.
Hello
Just out of interest I would like to know the physics in regards to a fan that is incorrectly mounted. In the attached photo the fan to my mind has been assembled back to front. I always thought that a fan back to front would push air rather than pull air or am I getting confused with the reversing of the fan rotation? In the case of this photo the leading edge of the fan blades is still closest to the radiator & the direction of rotation hasn’t changed, the only difference from a correctly attached fan is the curvature of the blades is reversed. So does this fan still draw air through the radiator but not as efficiently as a correctly mounted fan? Searching the internet I have found several 100’s & Mk1V’s with fans on back to front.
Cheers Peter
Frankly I don’t think it will have a great effect . The fan is only going to do much at low revs.However… looking back at old pics and squinting hard , it does seem that the steel spider part was on the front.
And for a further piece of trivia, pics taken in the factory show that , at least on that day, the ends of the alloy blades were masked off and left bare but the steel centre and inner ends of the alloy were painted
The red fan is a period performance enhancement. or perhaps a safety feature to help mechanics loosing fingers when the engine w as running.
My initial uncalculated, gut reaction is this fan design put on backwards could lower the cubic feet per minute by perhaps a factor of 2 when stopped and at idle, so maybe the temperature would rise a little faster at stop or very slow parade driving compared to correct fan mounting. Not the most desirable circumstances for more than a minute or two normally anyway, but not likely much of an issue since the fan is increasing air flow through radiator either way.
As a rule of thumb, people tend to look into design changes when a more than 10% difference is noted. It would seem curved fan shapes and a directional sense for the fan would have greater production costs than flat blades and so must be done for improvements worth incremental costs. Fan blade design is a pretty well-studied topic in engineering, both for axial flow efficiency and for noise considerations.
Curious to hear if anyone has experience with heating issues when fan is installed backwards. This could be a Yogi Berra circumstance, there is no problem if no one is having a problem.
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I agree with Roger and Ed. Mounting the fan the wrong way around doesn’t affect the basic angle of attack of the blades. The only change is to the curvature of the blades and as shown in the photo their scooping effect will be less effective but because the attack angle is still in the correct sense the fan will still pass air in the correct direction.
Peter
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It’s on back-to-front. If an aeroplane had its prop on this way it would struggle to taxi to the runway. The blade leading edge should have a shallow angle to cut the airstream. The blade twist then steepens to accelerate the air rearwards.
With the configuration shown the leading edge is at a ‘buttress’ angle, shovel-like, rather than a slicing angle, and cannot provide the same volume rearwards by a considerable amount. In addition the cupping of the blade facing the front creates a significant vacuum forward which is greater than would occur with the correct orientation. This has the effect of pulling back some of the air pushed through. This error also needs more energy to rotate at speed because of greater drag.
In short, it is wrong, and though it would push air, it will be quite inefficient. Think of the profile and shape of a boat propeller.
A quick visual reference is that the ‘tidy’ face is what you see under the bonnet, i.e. the full blade and rivet heads, not the mounting triangle. There is a technical reason for this, not a cosmetic one. When the fan is pushing air, the load on the blade is trying to bend it forward. The reaction (bending force/moment) should be taken on the triangular mounting tab, not the rivets. Some fan blades, particularly from the '50s onward, when operating revs increased, have a rib pressed down the middle to provide the resistance to flexing when in full song. And the rib is on the front face where the slight vacuum occurs, therefore not creating much turbulence.
Hope this is clear enough.
Quite right about the scooping effect, try pushing a snow shovel upside down.
The red blades caused by careless fingers have proven themselves so many times in saloon racing that it is one of the things by which sellers can prove track history. 
The green spider is of course proof of celebrity ownership.
rim shot
But seriously, folks.
One day when we have nothing better to do we could attempt to pin down this unpainted vs half painted blades thing.
I chose to do mine unpainted.
Hello
Thanks for explaining how the efficiency of a fan works, are you sure that the red on the blades is paint & not blood.
Cheers Peter
No, we’re not sure; it may be type O-O-O-Ow. 
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