<VV> Weber IDAs? Dellortos?

[Sethracer at aol.com]

In a message dated 1/22/2007 4:46:36 PM Pacific Standard Time,  
jwcorvair at aol.com writes:

Is  anyone running a pair of dual throat IDAs on their engine where the IDA 
is  attached to the manifold through an adapter to the single carb mount? Has  
anyone modified the manifold on a Corvair cylinder head to accept a dual  
throat IDA? I know that Warren LeVeque offers a DCOE modified for progressive  
operation on turbo engines; has anyone modified an IDA for progressive  
operation? (Basically the same carb, just vertical instead of  horizontal.)




In my experience, this would be a competition only set-up. I have seen two  
cars run that set up, the two down-draft 40 IDA 2-barrels, although,  
technically, each carb fed a plenum that then fed the cylinders witha separate  tube. 
Sort of like the bolt-on, but the plenum was lifted higher off the motor.  Both 
cars were race cars. The first one was the "Silver Fox"an SCCA winning tube  
framed sports racer with a mid-engined Corvair. It was converted to a  
Holley-carbed supercharged set-up, as it remains today, I believe. The  carb/manifold 
set up was installed on Louie Lira's 64 autocross car. I believe  he has 
moved away from it, but I am not sure, I haven't seen the car run in  several 
years. I ran a similar set-up on a Street-Prepared autocross Corvair. I  used 
Dellorto 40 MM downdrafts - almost a clone of the 40 IDA Weber, with small  stacks 
adapting them to the stock carb pads. However, since, at the time,  nobody 
was converting the Webers (or Dellortos) to progressive operation, in  order to 
have any off throttle operation, the secondary chokes in the carbs  had to be 
greatly reduced in size from how they were operated in a tuned  port (single 
port per cylinder) operation. When a balance had been reached, I  was down to 
around 28-30mm chokes - around 1 and one-quarter inches. Sound  familiar? All 
out performance was on a par with a set of good Rochesters.  Cornering power 
was definitely better. But the car was very cold-blooded,  and, although it 
would keep running on start-up, still had poor off  idle throttle response. Woe to 
the driver that tried to sneak away from the  line. It would just die, unless 
the hammer was dropped with the RPM up. (Fun,  actually, but not for the 
street) I can testify that it is the same effect that  you see when all four 
Rochesters are ganged to open together. I would attempt  this setup only if 
progressive linkage was installed on each carb, or if you are  using Fuel injection 
throttle bodies to serve up the correct fuel mixture,  instead of carbs. - Seth 
Emerson