Correct Carb? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dads67 · 06-20-2006, 10:45 AM

I have a 1967 C10 250 six, 3 on the tree with a Rochester #7027009 carb on it that leaks a little. Looking for a rebuild kit, I discovered, according to the chassis overhaul manual I have, the CORRECT carb should be a 7027011 or 7027029. The one I have is apparently for the 292 6 . . .does it matter?

The timing is also set at 2 degrees ATDC, and the manual calls for 4 degrees BTDC . . . could the carb difference account for this?

Fred T · 06-20-2006, 12:14 PM

The carbs are all Rochestor model B, take the same kit and they all leak the same. You should be able to get a kit at the parts store. My question is what's leaking, it might and might not be fixable.

Timing should be set 4*B at a minimum. With a HEI, you can go as high as 10*, then back it off until it doesn't ping. If the cam is set properly, setting timing after tdc will hurt performance and fuel economy.

Dads67 · 06-21-2006, 09:39 AM

Thanks for the info Fred. It's leaking (just a little) at the front of the carb between the upper and lower halves. I fear it will only get worse!

The "carb king" told me they "won't even rebuild them", because they will leak again in six months . . . he suggested a carter, zenith or stromberg

Do all the rochestor Bs have the fuel line inlet on the passenger sid of the carb? I ordered two different pump to carb pre-bent fuel lines and they both have the line entering the fuel filter/carb at the front of the carb?

Brad · 06-21-2006, 11:02 AM

Those lines are for the Rochester MV which looks totally different than the B model.

ChevLoRay · 06-21-2006, 12:00 PM

There is one gasket between the bowl and the base. Make sure that the bottom of the bowl is not "less than perfectly flat". The cast iron base shouldn't be out of plane, but check both surfaces to be sure. If they're flat, the gasket should prevent any leakage. Make sure your threaded holes are in good shape, although I've not seen any that weren't good. You may want to use some thread locker sealer, just to be sure they don't loosen up.

While the carb you have may have been originally installed on a 292, I wouldn't sweat it unless you're going for concours correct.

Otherwise, you may want to think about a Clifford intake and headers, then go with a 400-500 cfm four-barrel....oh, and maybe a hotter cam...then, put in an HEI from a mid-late 70's 6-cylinder.

06-20-2006, 10:45 AM	#1
Dads67 Registered User Join Date: Jun 2006 Location: Herndon, VA Posts: 7	Correct Carb? I have a 1967 C10 250 six, 3 on the tree with a Rochester #7027009 carb on it that leaks a little. Looking for a rebuild kit, I discovered, according to the chassis overhaul manual I have, the CORRECT carb should be a 7027011 or 7027029. The one I have is apparently for the 292 6 . . .does it matter? The timing is also set at 2 degrees ATDC, and the manual calls for 4 degrees BTDC . . . could the carb difference account for this?

06-20-2006, 12:14 PM	#2
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Re: Correct Carb? The carbs are all Rochestor model B, take the same kit and they all leak the same. You should be able to get a kit at the parts store. My question is what's leaking, it might and might not be fixable. Timing should be set 4B at a minimum. With a HEI, you can go as high as 10, then back it off until it doesn't ping. If the cam is set properly, setting timing after tdc will hurt performance and fuel economy. __________________ Fred There is no such thing as too much cam...just not enough engine.

06-21-2006, 09:39 AM	#3
Dads67 Registered User Join Date: Jun 2006 Location: Herndon, VA Posts: 7	Re: Correct Carb? Thanks for the info Fred. It's leaking (just a little) at the front of the carb between the upper and lower halves. I fear it will only get worse! The "carb king" told me they "won't even rebuild them", because they will leak again in six months . . . he suggested a carter, zenith or stromberg Do all the rochestor Bs have the fuel line inlet on the passenger sid of the carb? I ordered two different pump to carb pre-bent fuel lines and they both have the line entering the fuel filter/carb at the front of the carb? Attached Images

06-21-2006, 11:02 AM	#4
Brad Out of the carpool lane. Join Date: Jan 2000 Location: Clark Co, WA Posts: 5,672	Re: Correct Carb? Those lines are for the Rochester MV which looks totally different than the B model. __________________ 1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten...

06-21-2006, 12:00 PM	#5
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Correct Carb? There is one gasket between the bowl and the base. Make sure that the bottom of the bowl is not "less than perfectly flat". The cast iron base shouldn't be out of plane, but check both surfaces to be sure. If they're flat, the gasket should prevent any leakage. Make sure your threaded holes are in good shape, although I've not seen any that weren't good. You may want to use some thread locker sealer, just to be sure they don't loosen up. While the carb you have may have been originally installed on a 292, I wouldn't sweat it unless you're going for concours correct. Otherwise, you may want to think about a Clifford intake and headers, then go with a 400-500 cfm four-barrel....oh, and maybe a hotter cam...then, put in an HEI from a mid-late 70's 6-cylinder. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.



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