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#77105 05/04/2007 3:22 AM | Joined: Aug 2005 Posts: 1,186 Shop Shark | | Shop Shark Joined: Aug 2005 Posts: 1,186 | Just put a rebuilt carb on my stock '54 one ton today and fired it up. Ran kinda sluggish for a bit then settled down. As it ran I could see it spitting gas into the top opening every few seconds. I'm guessing it shouldn't be doing that? Any ideas whats going on? Possibly too rich? Float problem? :confused: | | |
#77106 05/04/2007 3:31 AM | Joined: Sep 2006 Posts: 43 Apprentice | | Apprentice Joined: Sep 2006 Posts: 43 | 55 what carb.
there could be several problmes.
1) float level as you mentioned try setting 1/32 lower then specs if you have an old carb
2) too much fuel pressure coming to the carb from the fuel pump and is is pushing the needle open
3) bad seal somewhere in the carb and could be leaking from there try tightening th air horn by 1/2 a turn
good luck
chaimv | | |
#77107 05/04/2007 4:15 AM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | 55 1st suburban,
I'm not real clear on your description on 'spitting'. Do you mean you saw fuel being blown back, or spit up, out of the carburetor throat. Maybe you mean burbling out of the vent tube in the throat.
Stuart | | |
#77108 05/04/2007 9:00 AM | Joined: Apr 2005 Posts: 641 Shop Shark | | Shop Shark Joined: Apr 2005 Posts: 641 | yes you will see gas misting and dribbling down the venturi but it should not be getting outside of the carb.i started my 350 with holly carb and when it runs at idle it looks like a water spegot at slow drizzle money gone | | |
#77109 05/04/2007 1:51 PM | Joined: Aug 2005 Posts: 1,186 Shop Shark | | Shop Shark Joined: Aug 2005 Posts: 1,186 | I did replace the fuel pump with a new one, possibly it's forcing too much to the carb, that was one of my first thoughts also. As far as the spitting part, it's shooting a large size drop out the vent tube every few seconds. No apparent leaks outside the carb. | | |
#77110 05/04/2007 2:24 PM | Joined: Feb 2007 Posts: 385 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2007 Posts: 385 | The Rochester B has a unique idle system called 'snatch-idle'. "The idle tube is located across the nozzle from the main fuel system. Idle fuel is 'snatched' across the air gap into the idle down passage. One side benefit of this system is that the main nozzle passage is always full of fuel and ready to provide it on demand." From Roe and Fisher's 'Rochester Carburetors'
However, if what you are seeing is fuel coming out of the bowl vent, I don't think its the idle system. As suggested above, your float level may be off. (Just rebuilt my Rochester B and mine was off by 1/4 in drop and 1/8 with the needle valve closed.
You might also want to check the fuel pressure. I think the B is supposed to be supplied with 2-6 psi. That new fuel pump might be pushing too hard. If so, add a regulator.
195? Chevy 3800 dump truck
1973 Chevy C30 cab and chassis
1987 Suburban 3/4 ton 6.2L Diesel
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#77111 05/04/2007 10:07 PM | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | Make shure your float doesn,t have gas in it.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | |
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