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Rochester type B Carburetor Question #1301641 03/04/2019 2:55 AM
Joined: Feb 2019 Posts: 4,482 Upstate NY Phak1 AD Addict & Tinkerer
Phak1 AD Addict & Tinkerer Joined: Feb 2019 Posts: 4,482 Upstate NY	I just rebuilt my Rochester type B carburator on my 1952 3100 with a 59 235 installed and noticed two rectangular holes in the air horn. These holes lead directly into the fuel bowl with no filtration. I suspect they may be associated with the oil bath filter that was replaced with a paper air filter by a previous owner. I am curious as to what the purpose of these rectangular holes are for. Any ideas Attachments image.jpg (273.15 KB, 237 downloads) Last edited by Phak1; 03/04/2019 3:38 PM. Reason: Added picture Phil Moderator, The Engine Shop, Interiors and Project Journals 1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum

Re: Rochester type B Carburetor Question Phak1 #1301701 03/04/2019 7:11 PM
Joined: Aug 2018 Posts: 1,004 Saskatchewan 2 2ManyTrucks 'Bolter
2ManyTrucks 'Bolter 2 Joined: Aug 2018 Posts: 1,004 Saskatchewan	those are vents, to ensure that the fuel around the floats is at atmospheric pressure see attached photo Attachments Screen Shot 2019-03-04 at 9.09.32 AM.jpg (202.5 KB, 232 downloads)

Re: Rochester type B Carburetor Question Phak1 #1301703 03/04/2019 7:15 PM
Joined: Aug 2018 Posts: 1,004 Saskatchewan 2 2ManyTrucks 'Bolter
2ManyTrucks 'Bolter 2 Joined: Aug 2018 Posts: 1,004 Saskatchewan	more details to why vents were added attached -s Attachments Screen Shot 2019-03-04 at 9.14.31 AM.jpg (162.3 KB, 239 downloads) Screen Shot 2019-03-04 at 9.13.49 AM.jpg (136.47 KB, 236 downloads)

Re: Rochester type B Carburetor Question Phak1 #1301713 03/04/2019 9:08 PM
Joined: Dec 2008 Posts: 1,922 Long Island P panic 'Bolter
panic 'Bolter P Joined: Dec 2008 Posts: 1,922 Long Island	Venting the bowl to the A/C interior also prevents mixture from changing due to dirty air filter element.

Re: Rochester type B Carburetor Question Phak1 #1301738 03/05/2019 1:11 AM
Joined: Feb 2019 Posts: 4,482 Upstate NY Phak1 AD Addict & Tinkerer
Phak1 AD Addict & Tinkerer Joined: Feb 2019 Posts: 4,482 Upstate NY	Thanks for the info! It seems to me that the vents would allow dirt, water and other debris to enter the fuel bowl. Doesn’t sound like such a good solution. Thanks again! Phil Moderator, The Engine Shop, Interiors and Project Journals 1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum

Re: Rochester type B Carburetor Question Phak1 #1301754 03/05/2019 3:45 AM
Joined: Mar 2010 Posts: 10,280 Virginia 5 52Carl Renaissance Man
52Carl Renaissance Man 5 Joined: Mar 2010 Posts: 10,280 Virginia	Nice find, 2MT! I like the directions on how to drill a vent hole to upgrade older model carburetors. There have been a lot of posts about "empty bowls at startup" which might be solved by this fix. Carl 1952 5-window - return to "as built" condition \| 1950 3100 with a 235 and a T-5 transmission

Re: Rochester type B Carburetor Question Phak1 #1302015 03/07/2019 1:49 AM
Joined: Oct 2012 Posts: 233 Smyrna, TN USA M MtneerMike 'Bolter
MtneerMike 'Bolter M Joined: Oct 2012 Posts: 233 Smyrna, TN USA	thank you great information 1953 Chevy 3100 261 and SM420 53Chevy 3100 1953 Mack Firetruck 1972 Porsche 911 1986 Honda Goldwing

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