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Engine basics => Engine set up tips => Topic started by: roger gebhart on December 29, 2006, 04:35:34 AM

Title: os venturi
Post by: roger gebhart on December 29, 2006, 04:35:34 AM

I have an early os-25 rc and would like to turn a new venturi for c/l use. About what size ID wil I need for it to work well..

Title: Re: os venturi
Post by: L0U CRANE on December 29, 2006, 12:32:42 PM

Roger,

I don't have the dimensions for you, but it might help if you could clarify how old your 25 is...

MAX(Roman number series) 25? MAX-S 25? FP?

Luck and HNY!

Title: Re: os venturi
Post by: roger gebhart on December 29, 2006, 01:51:21 PM

Lou;   I'm guessing probably about 15 yrs probably a bit more. I have a 20 and a 25. The 25 has what appears to be a casting # on the case  2001 It also has AS stamped into one of the mounting flanges. The 20 is stamped as well but RN. I'm sure I can buy the venturis but that wouldn't be like I did it myself. I like to tinker anyway. rog

Title: Re: os venturi
Post by: Bob Reeves on December 29, 2006, 02:24:54 PM

Start with .240 with a .135 needle or .260 with a .155 needle

Title: Re: os venturi
Post by: roger gebhart on December 29, 2006, 02:39:51 PM

I will do that. Delrin Ok or must I use aluminun.  thanks rog

Title: Re: os venturi
Post by: James Lee on December 29, 2006, 03:24:35 PM

Roger
The aluminum will look the best, but delrin is very easy to machine!!  All the ones I make are delrin...  Great Stuff!!
Jim

Title: Re: os venturi
Post by: roger gebhart on December 29, 2006, 04:13:13 PM

You are right Delrin is neat stuff. One last question. Is there anyway to use th r/c NVA?   rog

Title: Re: os venturi
Post by: Leester on December 30, 2006, 09:55:05 AM

Roger, use P/N 22311000 available through Tower or A P/A NVA from Randy Smith (the PA's are tops) I don't think the R/C NV will work.

Title: Re: os venturi
Post by: John Miller on December 30, 2006, 10:39:49 AM

Quote from: roger gebhart on December 29, 2006, 04:13:13 PM

You are right Delrin is s havve shown that a post just may be the bneat stuff. One last question. Is there anyway to use th r/c NVA?   rog

 y1Yes there is, I've used them to make a post type assembly. Some studies have shown that a post is the most effecient form of NVA we can use. Using the modified RC assembly also puts the needle vavle on the same side as the tank outlet, and better yet, allows a straight shot with the fuel tubing.

You'll need to recompute the opening size considering that the post only extends half way into the opening. You also may need to shorten the post with a dremel tool so that it only extends half way into the opening. Mine setup like this, have worked perfectly for me.