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Engine basics => Engine set up tips => Topic started by: Louis Keller, Jr. on October 09, 2011, 12:50:07 PM

Title: angle of sprinkler hole-spray in venturi?
Post by: Louis Keller, Jr. on October 09, 2011, 12:50:07 PM

Put some replacement parts in an os 35-s. All is good and it runs great on the bench. Curious though, does the angle of spray into the venturi make a difference in the run of an engine and if so how? I've always kept them pointing down at the same angle of the venturi-carb base. What's best?

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: Chris Wilson on October 09, 2011, 04:04:49 PM

Rotate the spray bar so that the hole just disappears from view, that is the region of highest velocity and lowest pressure without suffering from any direct ram air effects.

Having it pointed straight down the throat of the venturi will place it into a turbulent area and may give inconsistent results.

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: scott matthews on October 11, 2011, 07:12:37 PM

After watching this post for 3 days I am assuming that this answer is totally correct? There are no differant opinions?

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: Chris Wilson on October 11, 2011, 07:55:13 PM

There are always other opinions mate but please view -
http://www.clacro.de/

Go to 'design/ venturis' and check out sketch 6B.

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: Louis Keller, Jr. on October 11, 2011, 08:32:44 PM

thanks fellas. Great info. will put to practice next session.

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: Chris Wilson on October 13, 2011, 03:51:58 PM

This quote sums it up VERY well -

"Using a manometer an an appropriate source of moving air, you will find that when rotating the spray bar in the venturi that draw is essentially constant when the hole is out of sight, and will bump up by about 15% when it is positioned in the exact right spot."

From -

http://controlline.org.uk/phpBB2/viewtopic.php?t=5236&highlight=
(second last post on page one.)

Cheers.

Still learning after 50 years.

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: Bill Little on November 01, 2011, 10:38:51 AM

Hi Chris,

Thanks for the info.  For what it's worth, I have always angled it slightly to the rear from vertical, just OOS.  This has always seemed to work great for 4-2 engines.

Big Bear

Title: Re: angle of sprinkler hole-spray in venturi?
Post by: Gene O'Keefe on November 01, 2011, 12:27:43 PM

I concur with Bill...to the REAR just out of sight vs rotating it to the front.