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Engine basics => Engine set up tips => Topic started by: James Lee on September 22, 2006, 02:46:07 PM

Title: OS 10 venturi size
Post by: James Lee on September 22, 2006, 02:46:07 PM

I need some help to find out the venturi size for an OS .10 FP or LA.  Inside dia and spraybar dia?  I need to make some venturis for a customer that is converting a pair of r/c (ptooey..) engines to CL  ;D  I have a ragged out 10 FP case from an r/c car to use as a gauge for the base...
Thanks for your help   ;D ;D
Jim  

Title: Re: OS 10 venturi size
Post by: Bob Reeves on September 22, 2006, 04:25:18 PM

Jim, how ya doin, glad to see you in computer land...

I made a spread sheet using info I found on the internet, it's pretty good as a starting point for 25 and up but have never tried it for anything that small..

It comes out with something like .220 for .135 spraybar and .231 with a .155.

Not sure if this helps or not..

Title: Re: OS 10 venturi size
Post by: Leester on September 22, 2006, 04:57:02 PM

Don't know if this helps but the p/n for venturi 10FP-S is 21112003  and NVA is 21111006

Title: Re: OS 10 venturi size
Post by: James Lee on September 22, 2006, 06:56:57 PM

I have the part #, but need to know inside dimension to make a new one ...   I can make a guess, but would like to start with a factory dimension...   
Bob, I'll catch you in Tulsa and we can talk...  ;D
Thanks
Jim

Title: Re: OS 10 venturi size
Post by: Leester on September 22, 2006, 07:04:03 PM

According to Towers tech notes the inside of the venturi is 6mm, no specs on the NVA.

Title: Re: OS 10 venturi size
Post by: Bob Reeves on September 22, 2006, 07:56:14 PM

6 mm is .236, if it comes with a .155 spray bar the spread sheet was pretty close.. Would be interesting to find out.

Title: Re: OS 10 venturi size
Post by: James Lee on September 22, 2006, 08:15:56 PM

The .236 sounds maybe close, but I think a .155 spraybar would be a bit big, I think the 25-40 has a .140 or a bit less spraybar...   I have the carb and will try to do some headscratching to see what I can come up with...  was hoping to avoid all that higher math...   ;D
Thanks all!  :)  ;D
Jim

Title: Re: OS 10 venturi size
Post by: James Lee on September 22, 2006, 08:58:10 PM

Well, it is amazing what some actual research will do  :P...  In my pile of useless stuff is an OS engine book with ALL the numbers, circa 1993.  And at some point in the forgotten past I had noted that the 10 FP venturi was a very few thousandths less than the 15 FP, and that they were interchangeable...   And Leester you are absolutely correct about the 6mm size!  The spraybar is .137 ....    :)   So, looks like approx size of .235 will be about right!!
What it boils down to, I shoulda done more looking before I opened my dumb computer...  :-[
Thanks all! :)
Jim