Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 06-01-2019, 04:35 PM   #1
Mulletwagon
Senior Member
 
Join Date: Jan 2019
Location: Florida Panhandle
Posts: 179
Default Balanced Carb

Does a balanced carb offer any significant benefit over a standard unit ? Are the benefits too insignificant to notice ? Do high-flow air filters preclude the need for a balanced carb ?
Mulletwagon is offline   Reply With Quote
Old 06-01-2019, 05:42 PM   #2
Werner
Senior Member
 
Werner's Avatar
 
Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 412
Default Re: Balanced Carb

Guten Abend,I did a lot of research and tried to do that. I first mounted a large K & B air filter. Then I mounted a tube to equalize the pressure of the float chamber to about area choke-flap.
Now the car runs well, but needs 20 liters / 100 kilometers (4 gal / 65 miles?) If I now remove the air filter, I notice no difference.

My conclusion: When installing a large-volume air filter with little flow resistance, air-ballancing is not absolutely necessary.
Attached Images
File Type: jpg P1090835.jpg (70.2 KB, 80 views)
__________________
Beste Gruesse aus Deutschland,
Werner


Ford Model A Roadster, 1928
Citroen 11 CV, 1947
Honda CB 450 K 1, 1968
Hercules Wankel Rotary Engine, 1976 (Canadian version)
Werner is online now   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 06-01-2019, 09:13 PM   #3
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 4,412
Default Re: Balanced Carb

An air filter fitted to a Model A carby might restrict the air flow and reduce the pressure from there on right into the manifold. Because the float bowl is originally vented to the atmosphere, the pressure in there does not change when the filter is fitted. That leaves the pressure in the bowl higher than in the throat of the carby. That means more fuel is pushed through and the motor runs rich. By pressure balancing the carby, the pressure in the bowl is made the same as in the throat so no extra fuel is supplied.
If you have a balanced carby you should notice no difference compared to the original if you run with or without an air filter. The only time there is a problem is if you run a restrctive air cleaner without balancing the carby. An air filter with little restriction causes little difference.
Hope I explained that clearly enough!
__________________
Life's journey is best undertaken slowly.
Synchro909 is offline   Reply With Quote
Old 06-02-2019, 07:09 AM   #4
chap52
Senior Member
 
chap52's Avatar
 
Join Date: Jun 2013
Location: Marana Arizona
Posts: 1,464
Default Re: Balanced Carb

Go check out the info from David Renner. Worth a look, Chap
http://rennerscorner.com/index.html
chap52 is offline   Reply With Quote
Old 06-02-2019, 10:57 AM   #5
Jim/GA
Senior Member
 
Jim/GA's Avatar
 
Join Date: May 2010
Location: Young Harris, GA
Posts: 1,364
Default Re: Balanced Carb

Quote:
Originally Posted by Mulletwagon View Post
Does a balanced carb offer any significant benefit over a standard unit ? Are the benefits too insignificant to notice ? Do high-flow air filters preclude the need for a balanced carb ?
Let me take these one at a time:

Benefit over a standard unit?: If you install an air filter and IF there is any restriction, it automatically compensates for the restriction. It's automatic at all throttle positions, all speeds.

Benefits too insignificant to notice?: On some cars, yes; on others, no. It really depends on how good the JETS are calibrated in the carb to begin with, and your skill at adjusting the GAV to compensate for the air filter if you do NOT use a balanced carb.

Many carbs have jets that are too large to begin with. Those cars run with the GAV fully closed and are still too rich. So add the air filter restriction and they are still too rich and you do not notice the difference. You can't adjust the GAV leaner to compensate for the air filter, because you already have the GAV closed.

This is what it sounds like Werner's Model A has. 20 liter/km is only 11.7 miles/gallon -- not good . These cars can do much better than that, if the carb is right. I regularly get 17-20 MPG with a balanced carb and an air filter.

Does high-flow air filter preclude the need? Technically, no. All air filters add some restriction. In practice, possibly. Do you care if the engine runs a bit richer than it needs to be? Gets slightly poorer gas mileage? If not, then don't worry about it. Install the air filter, adjust the GAV down a bit, and go!

Hope this helps!

.
__________________
Jim Cannon
"Have a Model A day!"
  • Repair
  • Restore
  • Drive
  • Enjoy!
  • Join MAFCA
http://tinyurl.com/Join-MAFCA
Jim/GA is offline   Reply With Quote
Old 06-02-2019, 11:39 AM   #6
Y-Blockhead
Senior Member
 
Y-Blockhead's Avatar
 
Join Date: Jul 2011
Location: Redondo Beach, CA
Posts: 3,890
Default Re: Balanced Carb

Quote:
Originally Posted by Jim/TX/GA View Post
Let me take these one at a time:

Benefit over a standard unit?: If you install an air filter and IF there is any restriction, it automatically compensates for the restriction. It's automatic at all throttle positions, all speeds.

Benefits too insignificant to notice?: On some cars, yes; on others, no. It really depends on how good the JETS are calibrated in the carb to begin with, and your skill at adjusting the GAV to compensate for the air filter if you do NOT use a balanced carb.

Many carbs have jets that are too large to begin with. Those cars run with the GAV fully closed and are still too rich. So add the air filter restriction and they are still too rich and you do not notice the difference. You can't adjust the GAV leaner to compensate for the air filter, because you already have the GAV closed.

This is what it sounds like Werner's Model A has. 20 liter/km is only 11.7 miles/gallon -- not good . These cars can do much better than that, if the carb is right. I regularly get 17-20 MPG with a balanced carb and an air filter.

Does high-flow air filter preclude the need? Technically, no. All air filters add some restriction. In practice, possibly. Do you care if the engine runs a bit richer than it needs to be? Gets slightly poorer gas mileage? If not, then don't worry about it. Install the air filter, adjust the GAV down a bit, and go!

Hope this helps!

.
Excellent write up Jim, as usual. Thanks for your time spent on a thorough explanation.

Werner indicated he is getting 16.25 mpg? (65/4) altho his numbers don't exactly jive?
__________________
Y-Blockhead
'30 Briggs Town Sedan
'55 Ford Ranchwagon
_________________________________
And once again that is just my 1 worth.


https://www.youtube.com/watch?v=aH2TvmjxIFM

Last edited by Y-Blockhead; 06-02-2019 at 12:00 PM.
Y-Blockhead is offline   Reply With Quote
Old 06-02-2019, 02:23 PM   #7
Werner
Senior Member
 
Werner's Avatar
 
Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 412
Default Re: Balanced Carb

double.
__________________
Beste Gruesse aus Deutschland,
Werner


Ford Model A Roadster, 1928
Citroen 11 CV, 1947
Honda CB 450 K 1, 1968
Hercules Wankel Rotary Engine, 1976 (Canadian version)

Last edited by Werner; 06-02-2019 at 05:41 PM.
Werner is online now   Reply With Quote
Old 06-02-2019, 02:24 PM   #8
Werner
Senior Member
 
Werner's Avatar
 
Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 412
Default Re: Balanced Carb

Correction fuel consumtion: per 100 ml is 7 1/2 und 6 1/4 gal.



Hallo, the consumption at 100 miles in city traffic is 4.75 and long-distance overland 4.15.


Note: the fuel bill takes into account that the speedometer / mileage meter records 5% too much.

The main nozzles to buy are probably all too big. I have reamers to adjust the caliber. But I do not know, if I solder the original hole, how deep the pinch hole must be, in order to get the smaller flow with the smaller caliber. This only works if I measure the flow rate of the original nozzle against the manipulated nozzle. I can not do that right yet.
__________________
Beste Gruesse aus Deutschland,
Werner


Ford Model A Roadster, 1928
Citroen 11 CV, 1947
Honda CB 450 K 1, 1968
Hercules Wankel Rotary Engine, 1976 (Canadian version)

Last edited by Werner; 06-03-2019 at 02:07 PM.
Werner is online now   Reply With Quote
Old 06-02-2019, 03:12 PM   #9
Chuck Sea/Tac
Senior Member
 
Chuck Sea/Tac's Avatar
 
Join Date: May 2010
Location: Between Seattle & Tacoma
Posts: 1,756
Default Re: Balanced Carb

Once soldered, they must be flow tested, for that exact reason. You don’t know how long the new restriction is?
Chuck Sea/Tac is offline   Reply With Quote
Old 06-02-2019, 07:54 PM   #10
Ruth
Senior Member
 
Join Date: May 2016
Location: Glide, Oregon
Posts: 272
Default Re: Balanced Carb

it is probably better to have a professional flow your jets if you don't have the proper equipment to test them. Renner's Corner has a good reputation and is not too costly. They air balance carbs also.
Ruth is offline   Reply With Quote
Old 06-02-2019, 10:46 PM   #11
eagle
Senior Member
 
eagle's Avatar
 
Join Date: Aug 2011
Location: Eagle Bend, MN
Posts: 1,469
Default Re: Balanced Carb

I have an original AirMaze. It collects a lot of dust and dirt. I adjust the GAV 1/4 turn in and then the car runs unchanged, no noticable decrease in gas mileage. Every time I clean the filter an re oil it, think about what would've been in the engine. Im sure some still gets through though. Ive thought about buying the paper cartridge for it but haven't yet. If I do use paper I'd want to turn the element up so wouldnt be a fire hazard.
__________________
"There are some that can destroy an anvil with a teaspoon and shouldn't be allowed to touch anything resembling a tool."
eagle is offline   Reply With Quote
Old 06-03-2019, 06:59 AM   #12
Werner
Senior Member
 
Werner's Avatar
 
Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 412
Default Re: Balanced Carb

Guten Tag,

yes, the problem is the depth of the calibrated bore, which unfortunately is unknown. I asked Renner's if he has smaller main jets in stock.

I wonder if I will build perhaps the replica of the flow rate device like Mr. Pargeter.
Attached Images
File Type: jpg P1100142.jpg (60.9 KB, 31 views)
__________________
Beste Gruesse aus Deutschland,
Werner


Ford Model A Roadster, 1928
Citroen 11 CV, 1947
Honda CB 450 K 1, 1968
Hercules Wankel Rotary Engine, 1976 (Canadian version)
Werner is online now   Reply With Quote
Old 06-03-2019, 09:15 AM   #13
Jim/GA
Senior Member
 
Jim/GA's Avatar
 
Join Date: May 2010
Location: Young Harris, GA
Posts: 1,364
Default Re: Balanced Carb

Quote:
Originally Posted by Werner View Post
Guten Tag,

yes, the problem is the depth of the calibrated bore, which unfortunately is unknown. I asked Renner's if he has smaller main jets in stock.

I wonder if I will build perhaps the replica of the flow rate device like Mr. Pargeter.
Purchase a complete set of flow-tested jets from Mr. Renner and install them in your carburetor. He will tell you exactly what flow rate each jet tested at. The jets all work as a set for good power and good fuel economy.

Or you can build the flow test apparatus. A lot of work for one set of jets. Worth the time if you think you may test a larger number of jets (for yourself or others).

You also need a good sealing float needle valve on the carb to get good fuel economy, and all of the jets and the drain plug on the carb must seal tightly.
You need to have a "dry carb" on the outside, no drips, weeping, etc., when the car sits.
__________________
Jim Cannon
"Have a Model A day!"
  • Repair
  • Restore
  • Drive
  • Enjoy!
  • Join MAFCA
http://tinyurl.com/Join-MAFCA
Jim/GA is offline   Reply With Quote
Old 06-03-2019, 02:32 PM   #14
Werner
Senior Member
 
Werner's Avatar
 
Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 412
Default Re: Balanced Carb

Hallo zusammen.

Correction fuel consumtion: per 100 ml is 7 7/8 in the city und 6 5/8 gal. longway overland!

Joe, thanks for your big effort!
I have a new 'Viton' needle float valve mounted. No drops if gas valve was forgoten. The carburetor is completely sealed, no sweat.

But the GAV seat was rusty. I rubbed it with a cross-head screwdriver. But now I do it better once more with a new needle, which I loop with valve grinding paste into the seat.

No, I'm the only one around here who has an A and DRIVE it. (No living room-parking car!) So you convinced me and therefore I buy a complete set of jets from Mr. Renner. I drive fuel without ethanol, so the jets have to be a bit smaller. Thanks for the advice that I will heed.
__________________
Beste Gruesse aus Deutschland,
Werner


Ford Model A Roadster, 1928
Citroen 11 CV, 1947
Honda CB 450 K 1, 1968
Hercules Wankel Rotary Engine, 1976 (Canadian version)
Werner is online now   Reply With Quote
Reply

Thread Tools
Display Modes

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

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 03:05 PM.