A/F variation with new fan

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Moparmal

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My SB has been running sweetly, no A/F issues, no pump shot problems (AFB 750) or Fuel delivery problems - its a well sorted car (finally) .

Recently I fitted a viscous fan, and blocked the heat crossover on my intake.

The car now runs SERIOUSLY cooler, to the point where even after 15 mins driving, the car "flat spots" at around 4000 rpm at WOT, and appears to be leaning out.

I richened the mixture by using richer metering rods - and it seems to have fixed the problem

BUT - I want to double check - :read2:

Am i correct in assuming that the cool running engine is causing poor vapourisation of the fuel?

If so -

What is the most appropriate fix?:

A.- RIchen the mixture (like I have done)

or

B. - change the thermostat so the engine runs warmer in our winter

As you can imagine, here in Australia we rarely have to worry about engines running too cold....so this is all new to me.
 
you would have to be running very cold for the fuel to start condensing and puddling in the intake/cylinders. I doubt its that cold.

How cold are we talking..
 
Thanks for the interest guys - I cant say what the operating temps are because my calibrated temp gauge is not working atm.......

I CAN say that before the factory gauge ran at half way between the "E" and "M" - now its lucky to pass the "T" or qtr mark!! :shock:

Yesterday I fattened the Primaries up one rod step, and that took the flat spot out at WOT - Then I G-Tech'd the car, ran a 5.35 0-60

I knew the car had more in it than that from previous tests, so i fattened the secs up by 2thou tonight and G Tech'd a 4.91!! - This is my 2nd best ever .

Of course I dont know if i can go "fatter" still - but Im waiting on a new calibration kit and then i can experiment with some more rod changes ....

So i guess the answer is - a cold air charge requires a richer mixture. :idea:
 
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