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Engine basics => Engine set up tips => Topic started by: frank mccune on May 25, 2023, 06:57:44 AM

Title: Venturi size for .40 Diesel?
Post by: frank mccune on May 25, 2023, 06:57:44 AM

      Hello all:

       I am planning to convert an Irvine .40 RC Diesel to cl use.  What size of a hole in the venturi would work? Could I just wire the RC carb open for cl use?

       Tia,

       Frank

Title: Re: Venturi size for .40 Diesel?
Post by: Peter in Fairfax, VA on May 25, 2023, 09:01:29 AM

Frank,

What's the venturi ID on the r/c carb?  That might suggest a starting point.

Yes, holding open the r/c carb has been done.  Some carbs even ease this by allowing the idle stop to hold it open (early O.S.)

Peter

Title: Re: Venturi size for .40 Diesel?
Post by: Dan McEntee on May 25, 2023, 03:11:12 PM

  A C/L venturi with a spray bar through it is way different than an open R/C carb with nothing to restrict it. If going with the R/C carb, set it with the throttle closed to about 2/3 throttle for initial running and see how you like it. Just set the needle for the RPM you want just like normal.
  Type at you later,
  Dan McEntee

Title: Re: Venturi size for .40 Diesel?
Post by: Peter in Fairfax, VA on May 25, 2023, 03:45:48 PM

Dan's got a point here.  An open "true venturi" ID is different than a venturi restricted by a spray bar.  As I understand it, if you calculate the "free area" carefully, the two are roughly equivalent.   

Title: Re: Venturi size for .40 Diesel?
Post by: frank mccune on May 25, 2023, 03:57:29 PM

       Thanks for the prompt replies. 

        Frank