That Theres 15.2 Sq mm AREA , free . In the intake at the min/ spraybar .
The olde Pi x R squared trip .
http://www.mathgoodies.com/lessons/vol2/circle_area.html Remembering R is HALF the D ( diameter ) so a verneer or drill bit measures the bore of the intake , we use HALF that at cucalate the AREA of the orrifice ,
by subtracting from that the area of bits bloking it , so a 4 mm dia spraybar in a 6.5 mm hole is 4 x 6.5 ( approx cos its round at the ends ! ) so - 26, call it 25 .
Crikey , , so half of 6.5 = 3.25 as ' R ' , x 3.14 = X itself = The Answer , minus the 25 bit .
With the big intake I think it only worked 4-2 as the Needle DID leak air in with the fuel . As when I sealed it with a bit of fuel tube on the needle/ spraybar there , it just ran in an even two .
THUS if I hadnt tried it with the loose rattly needle , I wouldve missed out big time . As It's had 10 + gallons thru it like that , and only a few tanks ' sealed .
( the sping/ clickers adjusted lightly against the needle, it holds the setting fine . Rolling a finger will adjust it , tho picks up finger on , drops to ' new ' setting finger off .
only need 2 or 3 clicks variation , as a rule . Bending the Vent ( the ends cut at 45 degrree ) so straight forward into the airstream , I had to put it 1/4 turn IN , for same setting .
That only lasted one sesion , worked better ( engine a lot steadier ) with the vent tangental to the airstream ) .
THUS , Id drag both your intakes ( Carb & Intake ) To The Field , And Try BOTH . As youll never know what your missing , unless you Try It . !
Re Bretts post BELOW , often on R.C. carbs you / I can LOCK the Barrel by tightening the Idle Stop Screw right in , till it bottoms . GENTLY . the Just Firm . One of those screws anyway .
Pic of the Nasty FOX BB 25/19 Intake , Line Bobbins used as seals Ea Side .
15.2 mm = .5984". Are you meaning the venturi bore or the bore of the intake boss in the crankcase, or is it a typo? What is a "7.5 dis"? I seldom understand Matt's posts. I spent a month in Aussie plus spent quite a lot of time with Aussies here, so I'm at a loss. Coffee Steve
OOPS ,
Dis is a Typo .should read DIA > ,
15.2 sq mm is from memory
7.5 squared off 'd be about 6 mm SQUARE .
thus 6 x 6 'd be 36 , minus the spraybar , 6 x 3.2 in this case . 18.6 ! so calcs a bit rough , but indicative .leaves 17.5 ish
True Calc is 15.2 . Square mm AREA , Not DIAMETER .
They robbed us of ' imperial ' measurements ', in ' New Maths ' back in 68 . Metrics , dollars & cents instead of pounds shillings & pence , in Newzealand . AND Stopped the free Milk at Schools !