Triumph Repair: Cooling Fan Backwards?, balance weights, blade metal

Question
Hi Howard,

Question regarding the engine cooling fan on a 1966 TR4A.  I suspect it is installed backwards.  It is the stock original four blade metal fan.  If I understand correctly the slightly convex side is supposed to face the radiator.  Even backwards, the blades are still angled the correct way to pull air but:
1) how can I confirm if it is backwards?
2) if it is, in fact, backwards, is it a big deal?  Will cooling be significantly improved by correcting it?
3) how easy is it to reverse?  Is it 5 minutes with four bolts out and four bolts in or...is it more complicated?  In the manual I see all sorts of locking plates and balance weights. I'm concerned once I get it off I'll never get it properly balanced again.

Thanks

Bob

Answer
Hi Bob,
All fan blades operate just like a house fan, Aircraft propellers etc. The convex part goes toward the air supply and the concave part goes toward the direction that the air is going to exit. In the case of almost all car engines the concave goes toward the engine and the convex part goes toward the radiator.
I am not familiar with any balance weights and all the TR-4s I seen had metal fans and mounted solid to the crankshaft.
Howard