R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro On-Road > Onroad Nitro Engine Zone

Thread Tools Search this Thread
Old 10-17-2009, 09:26 PM   #1
Tech Apprentice
Join Date: Sep 2009
Posts: 63
Default what is mixture control value used for?

Dear all

anyone has idea on mixture control value,what does it used for ,and when should adjust it?
Attached Thumbnails
what is mixture control value used for?-.jpg  
kakluote is offline   Reply With Quote
Old 10-18-2009, 01:28 AM   #2
Tech Champion
Roelof's Avatar
Join Date: Aug 2007
Location: Holland
Posts: 6,271
Send a message via ICQ to Roelof

It will work the same as the mixture needle, it will set the distance between the needle and the nozzle.

The only difference is when you screw in the one and screw out the other at the same distance you can move the nozzle in the airflow of the carb.

It can give you a piece of extra finetuning to optimize the engine, but it is advised to keep it flush with the housing.
The quality of an answer comes with the quality of the question.
Roelof is offline   Reply With Quote
Old 10-19-2009, 03:24 PM   #3
Tech Master
afm's Avatar
Join Date: Nov 2003
Location: lima-peru
Posts: 1,807

Originally Posted by kakluote View Post
Dear all

anyone has idea on mixture control valve,what does it used for ,and when should adjust it?

The Mixture Control Valve, is actually the main jet of the carburator, commonly called mid range needle.

The dimensions of the this main jet (brass needle), its position relative to the venturi dictates the fuel curve of the carburetor (or how much fuel enters by each cfm of air drawn into the engine at a relative carb opening).

At idle speed, the engine is controlled by the low-end needle, and how much air passes into the engine via the position of the barrel. But when you start to move the barrel to allow more air to pass, in fact, you're moving the low-end needle too, allowing at the same time more fuel to pass too.

Depending at which opening of the barrel the main jet (brass needle) is totally uncovered, and the carburetor starts being mandated by the adjustment of the high-end needle, and how much fuel this last adjustment permits to pass can be varied, and the power band of the engine too, but slightly, by screwing or unscrewing the main jet (mid range needle) and readjusting the low-end needle.

But be careful, screwing the main jet too further into the venturi can lead to mix and temperature problems, in fact, you're leaning the mid rpms, where the engine operates at partial opening of the carb, this can lead to problems and erratic operation.

This is why, on almost all the engine booklets they warn you about not touching this adjustment, because it comes factory tuned to itís ideal average.

The position of the main jet, relative to the venturi also changes the position on where and how much the vortex of air that enters into the carb varies how finely the fuel is sprayed into the air that enters (fuel is converted into a mist to be burned), a drop, no matter how little it is, doesn't burn and can create many and serious problems. This last can lead up to a conrod breakage (common) or piston breakage (not common but seen some) due to hydro lock.

Hope its clear

afm is offline   Reply With Quote

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gulf Coast RC Track Racers, Porter Texas (Houston) John Stranahan Texas Racing 2692 04-18-2013 10:18 AM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 10:15 PM.

Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net