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Alpina racer that raced at Monterey......what is this for?


jrkoupe

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In talking to someone who ran a Bavaria racecar with triple sidedrafts, he suggested he had lean running problems due to airflow under the hood. I would imagine that aluminum plate is all about preventing too much air, ie: leaning out the front sidedraft.

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I'm sure ya'll have seen the pics of the standing wave of fuel about 3-4 inches off the end of the trumpets.  This occurs on sidedraft carbs at certain engine speeds where the pressure wave created by a valve closing bounces all the way out of the trumpet.  The air stream past the trumpet end would blow the fuel in that wave away.   I would say the air stream is being deflected away from the trumpets so the fuel is not blown away.

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Fun thread. 

 

I'm going with shaving weight with (un)intended consequences.  I.E.Engine bay cooling/cooling the fluid/cold air to trumpets.  After all,  both sides are cut out.    More dis-consorting is the fkry in the passenger headlight pocket..!?  Name that apparatus..?!

 

I would love to see that standing wave photo mentioned above!

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My guess is to reduce turbulence around the first carb.  I had a similar issue where the front barrel of carb #1 would seriously flood starting at about 2000 rpm.  I spent months tracing possible vibration, standing waves, reversion, voodoo curses, etc.  By accident I put a piece of cardboard between the fan and the first carb and voila, problem solved.  Turbulence or low pressure from the air rushing past was pulling gas out of the main jet into the venturi.

 

The odd shaped 5 blade fan of the e9 seemed to be causing this.  Once I switched to a even spaced 9 blade fan I didn't need the air block.

 

So he must have determined that air swirling around the area of the brake reservoir was messing with his carb performance/mixture in some fashion and wants it flowing more evenly past all bbls.

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My guess is to reduce turbulence around the first carb.  I had a similar issue where the front barrel of carb #1 would seriously flood starting at about 2000 rpm.  I spent months tracing possible vibration, standing waves, reversion, voodoo curses, etc.  By accident I put a piece of cardboard between the fan and the first carb and voila, problem solved.  Turbulence or low pressure from the air rushing past was pulling gas out of the main jet into the venturi.

 

The odd shaped 5 blade fan of the e9 seemed to be causing this.  Once I switched to a even spaced 9 blade fan I didn't need the air block.

 

So he must have determined that air swirling around the area of the brake reservoir was messing with his carb performance/mixture in some fashion and wants it flowing more evenly past all bbls.

^^

 

I had this same issue on my TR-4 years back that almost drove me to be institutionalized....it was only remedied when someone with far more knowledge than I pointed out the possible problem, and a proposed the solution.  

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