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GENEBERG Samba Member
Joined: January 13, 2005 Posts: 22
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Posted: Wed Jul 15, 2015 3:23 pm Post subject: |
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These are the modified venturi that Doug was referring to.
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Wed Jul 15, 2015 4:31 pm Post subject: |
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A set of chokes like this for our 58's went into Flemming's Super Street engine,,, (making close to 300hp) Gained 17hp @ 8500rpm's,,, The road racing mazda,,, Gained 8 mph on the straight away (13b single58) Which is around 30% increase!!! Anton (my buddy in Reno) that has been helping me develope these for the last couple yrs. He went from 42 choke to Grooved 40 choke & gained 7 hp topend,,, and move peak torque down 1000 rpm's and increased it !!!! They come in different sizes Doug... |
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Dan Ruddock Samba Member
Joined: October 25, 2012 Posts: 3668 Location: Sarasota, in my adopted state of Florida
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Posted: Wed Jul 15, 2015 5:28 pm Post subject: |
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That could make all the 37's floating around more usefull.
Dan |
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j-dub Samba Member

Joined: November 09, 2003 Posts: 870 Location: Phoenix, AZ
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Posted: Thu Jul 16, 2015 8:27 pm Post subject: |
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Doug Berg wrote: |
A set of chokes like this for our 58's went into Flemming's Super Street engine,,, (making close to 300hp) Gained 17hp @ 8500rpm's,,, The road racing mazda,,, Gained 8 mph on the straight away (13b single58) Which is around 30% increase!!! Anton (my buddy in Reno) that has been helping me develope these for the last couple yrs. He went from 42 choke to Grooved 40 choke & gained 7 hp topend,,, and move peak torque down 1000 rpm's and increased it !!!! They come in different sizes Doug... |
This sounds super interesting. Would you say this technique is only helpful for race engines or would street engines also benefit? _________________ 1957 Oval rag
"POLICE STATION TOILET STOLEN ... Cops have nothing to go on." |
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Thu Jul 16, 2015 10:52 pm Post subject: |
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On our flowbench we have 2 meter's,,, 1 read's the volume,,, the other read's airspeed,,, Most flowbench's only read volume!!! We modify the IDA's to set screw the booster in!!! (secondary auxillary) this allow's us to rotate the booster 180 degree's in the carb,,, And run the airspeed probe in the booster,,, So we can read the vacuum on the E-tube (main jet) The grooved 40 chokes Anton is using,,, Had the same signal on the booster as a 38 choke,,, And the total volume was very close to the straight 42 choke!!! Mark @ GBE has a flow simulator on his computer @ home,,, He said this shape hole flowed over 15% more than a round hole of the exact same size !!! Doug... |
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modok Samba Member

Joined: October 30, 2009 Posts: 27728 Location: Colorado Springs
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Posted: Thu Jul 16, 2015 11:31 pm Post subject: |
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That's way cool. Thanks for sharing this, I will try it too!
Oh, and don't worry I won't tell anybody if it works or not, LOL |
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Thu Jul 16, 2015 11:52 pm Post subject: |
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The guy w/ the road racing Mazda( a lot like a Super Vee) He was complaining about how hard it was to drive thru the pit's @ pit speed even in low gear,,, We moved him from a 50 mm straight choke to a grooved 46 choke,,, He is very happy w/ the drivability in the pit's now,,, They figured it @ 30% increase in power because it's up over 160 mph down the straight away now!!! I believe it work's on all engine's!!! A greater volume of air @ a higher velocity is what we all dream of!!!! Doug... |
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vwsb74 Samba Member
Joined: July 30, 2009 Posts: 1201 Location: socal
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Posted: Fri Jul 17, 2015 12:38 am Post subject: |
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Hi guys! Where can I get a set of 38mm vents? _________________ 74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢 |
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Fri Jul 17, 2015 1:12 am Post subject: |
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I have a set here,,, they're just 37's opened up on the lathe!!! Doug... |
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vwsb74 Samba Member
Joined: July 30, 2009 Posts: 1201 Location: socal
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Posted: Fri Jul 17, 2015 1:21 am Post subject: |
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Doug Berg wrote: |
I have a set here,,, they're just 37's opened up on the lathe!!! Doug... |
How much? Can you post a clear pics? _________________ 74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢 |
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Fri Jul 17, 2015 11:53 am Post subject: |
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I'm pretty sure I can arrange to have your's cut @ GBE,,, Not sure on what kind of price??? They have a 4 day work week (closed on friday's) The shop is in Orange Cal. off of Ball Rd. Let me know!!! And "no" I can't do picture's yet!!!! Doug... |
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jfats808 Samba Member

Joined: December 10, 2007 Posts: 5022 Location: oahu hawaii
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Posted: Fri Jul 17, 2015 12:59 pm Post subject: |
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Doug, I'm interested as well. I'd like to get my 40mm vents modified. Please keep me in the loop.
And possibly my ida vents prepped for my race carbs. Those are 44s. _________________ 2276 IDA's 86C 11-1 DD
Rockstar Suzuki wrote: |
You might as well put 10 year build in your bullshit sig, as it will NEVER run. Also your a dick |
You can always learn something new, even from a fool.
Check your oil levels routinely! |
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Dan Ruddock Samba Member
Joined: October 25, 2012 Posts: 3668 Location: Sarasota, in my adopted state of Florida
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Posted: Fri Jul 17, 2015 2:19 pm Post subject: |
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Another berg inovation!!! Nice to see it happening again. Like to know how much it will cost for the mod. I will call GBE on monday.
Doug for a engine that likes size X standard type, how many mm smaller choke would you need to start with for the mod to achieve the same HP but the better low end or a split the difference?
Dan |
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Fri Jul 17, 2015 2:23 pm Post subject: |
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The other thing not mentioned here is "Profiling" the carb's,,, We swap the fluted butterflies for "non" fluted,,, and knife edge them,,, (swap to our throttle shaft's) or modify yours,,, (ours has adjustable squirter ramp) It's anywhere from 20 to 35 cfm improvement!!! which is about 15 to 18 hp increase!!! (on Johnny Loctite's)(John Schurger) I went up 20 some cfm and no change on the dyno!!! went back more mods to carbs up to 35 cfm improvement!!! and no change on the dyno!!! Sitting there smoking a cig staring @ the dyno,,, (In my head I heard Gene say... "Cant get it in if you cant get it out"!!!) Change to 1 7/8 header from 1 3/4 and "BOOM" 21 hp gain!!! Doug.... |
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Doug Berg Samba Member
Joined: March 18, 2015 Posts: 137 Location: Fallon NV.
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Posted: Fri Jul 17, 2015 7:08 pm Post subject: |
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Dan,,, the # of grooves is odd (7) so that the grooves are not opposed,,, so the cross section remains small,,, all of the math is based on the radius,,,, If say you have a 40 mm choke,,, And you start w/ a 37 choke for grooving and then cut a 42 mm groove in it,,, That gives you a 39.5 choke which out flow's the original 40,,, while still having the velocity closer to the 37 choke you started with!!! (18.5 + 21 = 39.5) I like "middle of the road".... When it comes to rod length,,, not too long & not too short,,, valve/port size,,,, not too big & not too small!!! It's funny "they" call it a "HAPPY MEDIUM" !!! (or just right!!!) Doug... |
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vwsb74 Samba Member
Joined: July 30, 2009 Posts: 1201 Location: socal
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Posted: Tue Aug 11, 2015 10:48 am Post subject: |
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Okay I'm doing some fine tuning. My current jetting is f11 65/120 idle 155mains 200airs 37 vents. The car runs smooth as butter from idle to 6k but I think it's still rich . I changed the idle to 60/120 and now there some hesitation on transition so I know it's running lean. What should idle airs should I get 110or 115? Please I need your help so I can buy today thanks !
timing is 28* full advance / 8*idle _________________ 74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢 |
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[email protected] Samba Member

Joined: August 03, 2002 Posts: 12785 Location: Salt Lake City, Utah
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Posted: Tue Aug 11, 2015 11:36 am Post subject: |
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2 or 3 progression holes? The solution is to bring the mains in sooner, not keep the progression longer, UNLESS the carbs only have 2 prog holes. The problem is so large, that's why tuners and eventually Weber went to the 3 prog hole on the IDA. 2 is insufficient IMO.
vwsb74 wrote: |
Okay I'm doing some fine tuning. My current jetting is f11 65/120 idle 155mains 200airs 37 vents. The car runs smooth as butter from idle to 6k but I think it's still rich . I changed the idle to 60/120 and now there some hesitation on transition so I know it's running lean. What should idle airs should I get 110or 115? Please I need your help so I can buy today thanks !
timing is 28* full advance / 8*idle |
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vwsb74 Samba Member
Joined: July 30, 2009 Posts: 1201 Location: socal
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Posted: Tue Aug 11, 2015 11:46 am Post subject: |
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[email protected] wrote: |
2 or 3 progression holes? The solution is to bring the mains in sooner, not keep the progression longer, UNLESS the carbs only have 2 prog holes. The problem is so large, that's why tuners and eventually Weber went to the 3 prog hole on the IDA. 2 is insufficient IMO.
vwsb74 wrote: |
Okay I'm doing some fine tuning. My current jetting is f11 65/120 idle 155mains 200airs 37 vents. The car runs smooth as butter from idle to 6k but I think it's still rich . I changed the idle to 60/120 and now there some hesitation on transition so I know it's running lean. What should idle airs should I get 110or 115? Please I need your help so I can buy today thanks !
timing is 28* full advance / 8*idle |
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John, they have 3rd progression holes . _________________ 74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢 |
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vwsb74 Samba Member
Joined: July 30, 2009 Posts: 1201 Location: socal
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Posted: Tue Aug 11, 2015 2:07 pm Post subject: |
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vwsb74 wrote: |
[email protected] wrote: |
2 or 3 progression holes? The solution is to bring the mains in sooner, not keep the progression longer, UNLESS the carbs only have 2 prog holes. The problem is so large, that's why tuners and eventually Weber went to the 3 prog hole on the IDA. 2 is insufficient IMO.
vwsb74 wrote: |
Okay I'm doing some fine tuning. My current jetting is f11 65/120 idle 155mains 200airs 37 vents. The car runs smooth as butter from idle to 6k but I think it's still rich . I changed the idle to 60/120 and now there some hesitation on transition so I know it's running lean. What should idle airs should I get 110or 115? Please I need your help so I can buy today thanks !
timing is 28* full advance / 8*idle |
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John, they have 3rd progression holes . |
Why when I changed the idle jet I'm now having hesitation on 3-3500k rpm
Before it did not? I have hesitation also below 2000rpm and it smooth out until 3-3500k rpm and smooth again .
My understanding is stumble below 2000rpm small idle jet, stumble 3k-4000k rpm small main jets is this correct? _________________ 74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢 |
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vwsb74 Samba Member
Joined: July 30, 2009 Posts: 1201 Location: socal
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Posted: Tue Aug 11, 2015 4:30 pm Post subject: |
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Pulled the 60 and put back the 65 , while waiting for the 110 air holder from Italy . Update you guys in few days. Right now the 65/120 combo is like butter with a hint of gas  _________________ 74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢 |
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