X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m26.mx.aol.com ([64.12.137.7] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 992376 for flyrotary@lancaironline.net; Mon, 20 Feb 2006 22:22:45 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.7; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m26.mx.aol.com (mail_out_v38_r7.3.) id q.278.53a5f0d (3310) for ; Mon, 20 Feb 2006 22:21:58 -0500 (EST) From: Lehanover@aol.com Message-ID: <278.53a5f0d.312be156@aol.com> Date: Mon, 20 Feb 2006 22:21:58 EST Subject: Re: [FlyRotary] Weber 48 To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1140492118" X-Mailer: 9.0 SE for Windows sub 5022 X-Spam-Flag: NO -------------------------------1140492118 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 2/20/2006 5:31:55 PM Eastern Standard Time, downing.j@sbcglobal.net writes: Lynn; Today I got to looking into the Weber 48. It has a 180 main, 160 air correction and F-7 emulsion tubes, with 42 mm chokes. Are these figures in the ball park. Looking at the answers you have sent me, its close. I really have no exact answer for that one. We have all kinds of tricks done to the carb to get Max flow at over 9,000 RPM. So our booster signal is way below what a stock booster or auxiliary venturi would generate. So, a 210 main and an 80 air is meaningless. A bit over 12:1 FA is just right, and that should read 1500 EGT at 6,500 RPM. A Bridgeport 12A will do 173 HP at those settings. A street ported 13B about 180 HP. Try to stay below 1650 in any case. Start with what you have and see what static RPM it will pull. Then just tune it from there. Spark at 25 degrees is plenty. Richer / leaner overall is the main jet size, and richer/ leaner at the top RPM is the air corrector jet. Smaller jet is richer. Bigger jet is leaner. Also the springs are set up to close the carb if the cable becomes disconnected. Do you remove these and use an external spring to keep the carb open or is there some way to turn these springs around. Thought I had better ask before I tear into it. I have never looked at this. I would think that removing the stock spring would be easy enough. Then the pull open spring could be very light. This sounds like an area where ground only and flight only should be two different items. Uncommanded full throttle on the ground could be more excitement that you can stand. Another question is, do I need a regulator for the Carter electric fuel pumps. Jegs has one by Quick Fuel which has a bypass feature and it says that it is for steady output electric fuel pumps. Yes, a regulator is required. The Weber needle and seat, will work OK up to about 4 pounds, then it will overpower the float and start dripping out of the boosters. We use a Holley but many good ones are available. We use a 350 Gross jet and 6 pounds just to keep enough flow at 9,600. We don't care if the boosters drip. We don't use the engine below 7,600 RPM. It looks like next winter I can install two high pressure fuel pumps and just flip the low pressure ones off and switch the high pressure ones on and use the Weber for the throttle body. I will need to machine two ports for the secondary injectors and weld them on the intake manifold. Does this sound like a viable solution for a duel fuel system? Yes. If there is time allowed to use up the float bowl fuel before injection starts. The Wittman Tailwind I'm building has a 34 gallon fuel tank in the cowl which flows down to a gascolator, then into two fuel pumps, which are lower than the gascolator, then pumped up to the carb. Thank you. JohnD Working on systems between cowl work. I will be doing the dual fuel Weber on mine as well. Lynn E. Hanover -------------------------------1140492118 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 2/20/2006 5:31:55 PM Eastern Standard Time,=20 downing.j@sbcglobal.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Lynn;  Today I got to looking into t= he Weber=20 48.  It has a 180 main, 160 air correction and F-7 emulsion tubes, wi= th=20 42 mm chokes.  Are these figures in the ball park.  Looking at t= he=20 answers you have sent me, its close.
 
I really have no exact answer for that one. We have all kinds of tricks= =20 done to the carb to get Max flow at over 9,000 RPM. So our booster signal is= way=20 below what a stock booster or auxiliary venturi would generate. So, a 210 ma= in=20 and an 80 air is meaningless.
 
A bit over 12:1 FA is just right, and that should read 1500 EGT at= =20 6,500 RPM. A Bridgeport 12A will do 173 HP at those settings. A street=20 ported 13B about 180 HP.
Try to stay below 1650 in any case. Start with what you have and s= ee=20 what static RPM it will pull. Then just tune it from there. Spark at 25 degr= ees=20 is plenty. Richer / leaner overall is the main jet size, and richer/ le= aner=20 at the top RPM is the air corrector jet. Smaller jet is richer.
Bigger jet is leaner.  
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
 
 Also the springs are set up to clos= e the=20 carb if the cable becomes disconnected.  Do you remove  these an= d=20 use an external spring to keep the carb= open or=20 is there some way to turn these springs around. Thought I had better ask=20 before I tear into it.
 
I have never looked at this. I would think that removing the stock spri= ng=20 would be easy enough. Then the pull open spring could be very light. This so= unds=20 like an area where ground only and flight only should be two different items= .=20 Uncommanded full throttle on the ground could be more excitement that you ca= n=20 stand.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
 
Another question is, do I need a regulato= r for=20 the Carter electric fuel pumps.  Jegs has one by Quick Fuel which has= a=20 bypass feature and it says that it is for steady output electric fuel= =20 pumps.
Yes, a regulator is required. The Weber needle and seat, will work OK u= p to=20 about 4 pounds, then it will overpower the float and start dripping out= of=20 the boosters. We use a Holley but many good ones are available. We use a 350= =20 Gross jet and 6 pounds just to keep enough flow at 9,600. We don't care if t= he=20 boosters drip. We don't use the engine below 7,600 RPM. 
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
 
It looks like next winter I can install t= wo=20 high  pressure fuel pumps and just flip the low pressure ones off and= =20 switch the high pressure ones on and use the Weber for the throttle=20 body.  I will need to machine two ports for the secondary inject= ors=20 and weld them on the intake manifold.  Does this sound like = ;a=20 viable solution for a duel fuel=20 system? 
Yes.
If there is time allowed to use up the=20= float bowl=20 fuel before injection starts. 
 
The Wittman Tailwind I'm building has a 3= 4 gallon=20 fuel tank in the cowl which flows down to a gascolator, then into two fuel= =20 pumps, which are lower than the gascolator, then pumped up to th= e=20 carb.  Thank=20 you.  JohnD       Working on=20 systems between cowl work.
I will be doing the dual fuel Weber on mine as well.
 
Lynn E. Hanover
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