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| | | | Joined: Jun 2015 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Jun 2015 Posts: 59 | I have a 1962 gmc with a 261 and it has the the 261 carb(larger throat size) would this be the dreaded Rochester B? It has no ID tag.
1962 GMC 920 step side 261 4 spd
| | | | | Joined: Jan 2014 Posts: 3,677 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,677 | If you really have a 261 (would be odd in a 62 gmc), very good chance the carb is a "B." There are instructions on the board for posting pictures. That would tell us for sure.
Does it run ok? The B probably deserves most of the criticism thrown at it, but there are also countless millions of them still working fine.
Last edited by JW51; 12/13/2015 1:48 PM.
1951 3100
| | | | | Joined: Dec 2008 Posts: 1,922 'Bolter | | 'Bolter Joined: Dec 2008 Posts: 1,922 | | | | | | Joined: Feb 2004 Posts: 29,751 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,751 | Don't the Canadian GMC's run Chevy engines? If it's not the original engine it could be a transplant from a "Pontiac" that would probably be a bolt-in swap up there in ice cube land!
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | That is the style Rochester that was used on later 235s/261s (with an air cleaner bolt on the top of the carb).
"Dreaded B?" - I think that later castings was not so prone to leaks between top/bottom of the carb (compared to earlier Rochester B/BC carbs).
Yes, the 261 was used on small Canadian GMC trucks starting in 1954. It was probably used on trucks through 62/63 (whenever 261 production ended in Canada).
Post the serial number (code) pressed into the block rearward of where the distributor goes into the block. Someone here might know the Canadian codes? | | | | | Joined: Jun 2015 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Jun 2015 Posts: 59 | This is the original engine block number matches ID tag, I have not seen it run yet ,engine had a major failure before I bought it. Engine is now rebuilt and was looking for a carb kit.
1962 GMC 920 step side 261 4 spd
| | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | I wouldn't worry about a Rochester B. I have one on my truck and it gives me great service. | | | | | Joined: Jan 2014 Posts: 3,677 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,677 | Isn't the 261-sized "B" a pretty unique critter?
1951 3100
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Isn't the 261-sized "B" a pretty unique critter? Yes, "unique" to the 261 engine The 261 Rochester B had a larger venturi throat inner diameter and a larger throttle body inner diameter (compared to the 235 Rochester B). It looks like 1958-1963 261 carb specs were the same but the air cleaner attachment might have changed in 1960? Maybe someone knows when the air cleaner attachment changed? The 1954-1959 261 Rochester carb model number was 7005140 The 1960-1963 261 Rochester carb model number was 7015143 | | |
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