The Ford Barn

Ed in Maine · 08-31-2013, 09:16 AM

I hope I picked the correct forum. I am rebuilding a Model B Carb and I am flow testing the jets. The compensator jet is a straight tube with two tiny holes in the side. The flow data that I got for this jet is 110 -118 ml/min. This tube is like a "fire hose" and would pass a lot more that 110 - 118 ml/min. Is this the flow data for just the two tiny holes in the side? I am thinking that if this tube is clean, it doesn't have to be tested since there is no calibrated orifice. Let me know what you guys think. Thank you, Ed

MikeK · 08-31-2013, 10:22 AM

Vince Falter's website, Ford Garage has a lot of data on B carbs, including all jet flow rates from several noted rebuilders. Look HERE.

lindy williams · 08-31-2013, 07:03 PM

The jet you described sounds like the main jet not the compensator jet. The compensator jet is a very short jet, about 3/8" long .

Ed in Maine · 09-01-2013, 03:30 PM

Hi Lindy, I am talking about the short jet, it is actually 9/16 in. from the top of the hex. Otherwise it is just a straight tube. Vince's site does list the flow data of 110 - 118 ml/min. This is my second go around with this carb. It initially ran too rich in the car. Ed

Purdy Swoft · 09-01-2013, 04:46 PM

I always called that little jet in the bottom of the bowl with a slot head, the compensator jet. You say that the carb is running rich. The GAV should be used differently with the B carb. After warmup the B carb should run with the GAV closed all the way. If it won't run with the GAV closed after warm up, there is a problem with the carburetor. Over restrictive air filters or any air filters in my book , causes updraft carburetors to run richer.

Ed in Maine · 09-02-2013, 10:15 AM

Sponsored Links (Register now to hide all advertisements)

Thank you for your comments, I do have the 32 service bulletins on the Model B carb on how to use the carb. It would be helpful to me if someone could tell me if this compensator jet is supposed to have a tiny calibrated hole at the end of the jet that gives the 110 - 118 ml/min. The jet I have is just a straight tube about 1/16 in. ID with the hex for installation. This is the short jet. My jet could be an incorrect repro but I could solder it up and calibrate it to the correct flow rate published by Vince Falter. Ed

Mitch//pa · 09-02-2013, 10:20 AM

call renners he is very helpful and also sells flowed jets
http://www.rennerscorner.com/index.html

Benson · 09-02-2013, 10:58 AM

1. The B carb CAP jet is the one that is about same size and length as the main jet and has two small holes in the side of the shaft.

2. The COMP jet is a small jet 3/8ths tall that looks just like the Model A comp jet.

The Flow rate on the larger CAP jet ranges from 320 to 520 as published in Vince Falter's web page that was posted above. As Far as I know the figures are correct.

When George De Angelis made the orginal Model B carb diagram years ago there was an error where the COMP jet and CAP jet were miss-identified. The names were swapped on the diagram.

The missinformation was copied in more than several diagrams based on the original.

H was called the Cap jet.

F was called the comp jet.

This is just backwards from the truth.

H is really the Comp Jet

F is really the Cap jet.

Gordon Biggar found this error in the early 2000s while working with Rex on their carb book and asked George De Angelis about it.

George agreed that there was an error and corrected the drawing which was published in Gordon Biggar and Rex Reheis' Book in 2004.

The corrected diagram is found on Page B-3 of the Gordon Biggar / Rex Reheis book.

If you look at your copy of the drawing, right below the "H" and if it does not say "G. D. 04" then you have the old diagram.

I have seen the miss information in several places even in one copy of the 1932 Ford Service Bulletins and other places.

I would post the diagram but it would be a violation of George De Angelis and Gordon's copyrights.

Purdy Swoft · 09-02-2013, 11:26 AM

Quote:

Originally Posted by Benson

1. The B carb CAP jet is the one that is about same size and length as the main jet and has two small holes in the side of the shaft.

2. The COMP jet is a small jet 3/8ths tall that looks just like the Model A comp jet.

The Flow rate on the larger CAP jet ranges from 320 to 520 as published in Vince Falter's web page that was posted above. As Far as I know the figures are correct.

When George De Angelis made the orginal Model B carb diagram years ago there was an error where the COMP jet and CAP jet were miss-identified. The names were swapped on the diagram.

The missinformation was copied in more than several diagrams based on the original.

H was called the Cap jet.

F was called the comp jet.

This just backwards from the truth.

H is really the Comp Jet

F is really the Cap jet.

Gordon Biggar found this error in the early 2000s while working with Rex on their carb book and asked George De Angelis about it.

George aggreed that where was an error and corrected the drawing which was published in Gordon and Rex Reheis' Book in 2004.

The corrected diagram is found on Page B-3 of the Gordon Biggar / Rex Rehies book.

If you look at your copy of the drawing, right below the "H" and if it does not say "G. D. 04" then you have the old diagram.

I have seen the miss information in several places even in one copy of the 1932 Ford Service Bulletins and other places.

Very good !!!!!!! Thanks for bringing the facts to light. Lots of WRONG info has been published in many books!!!

Benson · 09-02-2013, 11:35 AM

Note I have made some changes to the original posting ... so check for corrections and additions if you copied or read it right after I posted it

Purdy Swoft · 09-02-2013, 01:41 PM

Still very good. My main thought was the error where the compensator jet was confused with the cap jet. The jets are totally different and have different function. Thanks again for shedding light on the issue.

Ed in Maine · 09-02-2013, 06:52 PM

Thank you for your excellent post. This misinformation would have kept me guessing for a long time. I will take a second look at my copy of the 32 Service Bulletins. Ed

Benson · 09-02-2013, 08:19 PM

1. June 1932 SB page 10, Fig 13 shows the two jet names reversed ...

2. The green parts book dated 1950 Page (picture) 424 and has the parts correctly identified.

Part number index is on page 435 for B-9538 cap jet

Part number indexes are on page 437 for B-9575 Comp jet

Benson · 09-02-2013, 10:01 PM

You are welcome ... glad to help!

08-31-2013, 09:16 AM	#1
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,193	Model B Carb, Compensator Jet I hope I picked the correct forum. I am rebuilding a Model B Carb and I am flow testing the jets. The compensator jet is a straight tube with two tiny holes in the side. The flow data that I got for this jet is 110 -118 ml/min. This tube is like a "fire hose" and would pass a lot more that 110 - 118 ml/min. Is this the flow data for just the two tiny holes in the side? I am thinking that if this tube is clean, it doesn't have to be tested since there is no calibrated orifice. Let me know what you guys think. Thank you, Ed

08-31-2013, 10:22 AM	#2
MikeK Senior Member Join Date: May 2010 Location: Windy City Posts: 2,919	Re: Model B Carb, Compensator Jet Vince Falter's website, Ford Garage has a lot of data on B carbs, including all jet flow rates from several noted rebuilders. Look HERE.

08-31-2013, 07:03 PM	#3
lindy williams Senior Member Join Date: May 2010 Posts: 335	Re: Model B Carb, Compensator Jet The jet you described sounds like the main jet not the compensator jet. The compensator jet is a very short jet, about 3/8" long .

09-01-2013, 03:30 PM	#4
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,193	Re: Model B Carb, Compensator Jet Hi Lindy, I am talking about the short jet, it is actually 9/16 in. from the top of the hex. Otherwise it is just a straight tube. Vince's site does list the flow data of 110 - 118 ml/min. This is my second go around with this carb. It initially ran too rich in the car. Ed

09-01-2013, 04:46 PM	#5
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Model B Carb, Compensator Jet I always called that little jet in the bottom of the bowl with a slot head, the compensator jet. You say that the carb is running rich. The GAV should be used differently with the B carb. After warmup the B carb should run with the GAV closed all the way. If it won't run with the GAV closed after warm up, there is a problem with the carburetor. Over restrictive air filters or any air filters in my book , causes updraft carburetors to run richer.

09-02-2013, 10:15 AM	#6
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,193	Re: Model B Carb, Compensator Jet Sponsored Links (Register now to hide all advertisements) Thank you for your comments, I do have the 32 service bulletins on the Model B carb on how to use the carb. It would be helpful to me if someone could tell me if this compensator jet is supposed to have a tiny calibrated hole at the end of the jet that gives the 110 - 118 ml/min. The jet I have is just a straight tube about 1/16 in. ID with the hex for installation. This is the short jet. My jet could be an incorrect repro but I could solder it up and calibrate it to the correct flow rate published by Vince Falter. Ed

09-02-2013, 10:20 AM	#7
Mitch//pa BANNED Join Date: May 2010 Location: Bucks County, PA Posts: 11,454	Re: Model B Carb, Compensator Jet call renners he is very helpful and also sells flowed jets http://www.rennerscorner.com/index.html

09-02-2013, 10:58 AM	#8
Benson Senior Member Join Date: May 2010 Location: Cen~Col - Central Highlands Posts: 2,757	Re: Model B Carb, Compensator Jet-ERROR in Diagram 1. The B carb CAP jet is the one that is about same size and length as the main jet and has two small holes in the side of the shaft. 2. The COMP jet is a small jet 3/8ths tall that looks just like the Model A comp jet. The Flow rate on the larger CAP jet ranges from 320 to 520 as published in Vince Falter's web page that was posted above. As Far as I know the figures are correct. When George De Angelis made the orginal Model B carb diagram years ago there was an error where the COMP jet and CAP jet were miss-identified. The names were swapped on the diagram. The missinformation was copied in more than several diagrams based on the original. H was called the Cap jet. F was called the comp jet. This is just backwards from the truth. H is really the Comp Jet F is really the Cap jet. Gordon Biggar found this error in the early 2000s while working with Rex on their carb book and asked George De Angelis about it. George agreed that there was an error and corrected the drawing which was published in Gordon Biggar and Rex Reheis' Book in 2004. The corrected diagram is found on Page B-3 of the Gordon Biggar / Rex Reheis book. If you look at your copy of the drawing, right below the "H" and if it does not say "G. D. 04" then you have the old diagram. I have seen the miss information in several places even in one copy of the 1932 Ford Service Bulletins and other places. I would post the diagram but it would be a violation of George De Angelis and Gordon's copyrights. Last edited by Benson; 09-02-2013 at 08:55 PM. Reason: Spelling

09-02-2013, 11:35 AM	#10
Benson Senior Member Join Date: May 2010 Location: Cen~Col - Central Highlands Posts: 2,757	Re: Model B Carb, Compensator Jet Note I have made some changes to the original posting ... so check for corrections and additions if you copied or read it right after I posted it

09-02-2013, 01:41 PM	#11
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Model B Carb, Compensator Jet Still very good. My main thought was the error where the compensator jet was confused with the cap jet. The jets are totally different and have different function. Thanks again for shedding light on the issue.

09-02-2013, 06:52 PM	#12
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,193	Re: Model B Carb, Compensator Jet Thank you for your excellent post. This misinformation would have kept me guessing for a long time. I will take a second look at my copy of the 32 Service Bulletins. Ed

09-02-2013, 08:19 PM	#13
Benson Senior Member Join Date: May 2010 Location: Cen~Col - Central Highlands Posts: 2,757	Re: Model B Carb, Compensator Jet 1. June 1932 SB page 10, Fig 13 shows the two jet names reversed ... 2. The green parts book dated 1950 Page (picture) 424 and has the parts correctly identified. Part number index is on page 435 for B-9538 cap jet Part number indexes are on page 437 for B-9575 Comp jet Last edited by Benson; 09-02-2013 at 08:40 PM.

09-02-2013, 10:01 PM	#14
Benson Senior Member Join Date: May 2010 Location: Cen~Col - Central Highlands Posts: 2,757	Re: Model B Carb, Compensator Jet You are welcome ... glad to help!