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#1 |
Registered User
Join Date: Nov 2010
Location: Alabama
Posts: 739
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Carburetor Woes
I've got a 1970 C50 that had been sitting for about 10 years. Ive got the truck running, but it still has some problems. First of all, it won't run with choke completely open. It has to stay partially closed or it will quit running. It doesn't accelerate good and when pulling hills, it won't go over 15-20 mph. It starts and runs great, but it seems like the carb is stopped up.
Here's what I've done so far: New fuel pump New fuel filter (in-line, the filter at the carb was removed before I got it) New fuel tank New sending unit Blew out the fuel lines with air Fresh gas Added Seafoam and sprayed carb cleaner in the carb New air filter Is the carb stopped up? What's the best way to clean it out? Thanks! |
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#2 |
Registered User
Join Date: Jul 2012
Location: Ft Wayne Indiana
Posts: 1,204
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Re: Carburetor Woes
It sounds like you're just running lean?
But I'm wondering if it could be ignition related too.
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71 K20 64 GMC mud truck |
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#3 |
Senior Member
![]() Join Date: Nov 2001
Location: Rapid City, SD
Posts: 2,281
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Re: Carburetor Woes
Rebuild the carb.
Kits are very affordable.
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My Trucks: 1967 Chevrolet Short Wide Box 327 TH350 9" w/3.90 gears paint will be White - Current Project 1967 Chevrolet Custom LWB 283 TH400 3.73 Posi, no-AC, no-PS, no-PB, bench-seat, small-window - mostly orig driver 1967 Chevrolet CST LWB originally a 327 TH400 3.73 Posi AC PS PB, had Buddy Buckets, Small Window - parts truck 1967 Chevrolet CST LWB, 283 MT 3.73 had Buddy Buckets, Panoramic Window - parts truck 2001 Chevrolet 3500 2WD Crew Cab Dually 8.1L Allison White |
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#4 |
Registered User
![]() Join Date: Feb 2014
Location: West Iowa
Posts: 1,106
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Re: Carburetor Woes
In this situation, I have removed the carb. Disassemble and submerge is the best carb cleaner I could find for 1 to 7 days- depends on how dirty it is and how big of a hurry I am in. I then spray all the passages out with pressurized cleaner. re-assemble with a re-build kit. Then finally adjust as needed to idle/run/accelerate. Good Luck, Bruce
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#5 | |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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![]() Quote:
You have to get inside the carb and clean out the passages, bowls, etc to get a good baseline. Whatever you do....don't try to solve this by leaving the carb on the truck and 'putzing' and poking from outside. Remove it (takes 15 minutes tops) and get it on a bench. The first thing I would do is to get the top (air horn) off of it and take a look in the main fuel chamber to see what sort of crap is in there. At this point you haven't affected or adjusted anything...simply investigated. If you haven't rebuilt a carb before don't panic.....just proceed carefully. Keep us posted and remember...remove the carb, get it on a workbench, take your time and proceed carefully....it will pay dividends over 'screwdriver' putzing from the outside. Very Important Note: Before you start anything....take some pics as you go, so you know and remember exactly where everything went and where it should go back to. My two bits. Coley
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....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#6 |
Registered User
![]() Join Date: Jun 2014
Location: Houston, Texas
Posts: 722
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Re: Carburetor Woes
man why does that carb look so small? I'm new to these trucks, but my stock q-jet was much bigger looking.
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#7 | |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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Re: Carburetor Woes
Quote:
Its a 2 bbl Rochester, this is why it looks so much smaller. Coley
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....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#8 |
Registered User
![]() Join Date: Feb 2014
Location: West Iowa
Posts: 1,106
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Re: Carburetor Woes
This is a 2 barrel, likely your carb is a 4 barrel.
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#9 |
Registered User
Join Date: Nov 2010
Location: Alabama
Posts: 739
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Re: Carburetor Woes
Ok, good advise guys. Thanks
However, I have a few more questions. I've never done much to one of these carbs, so I want to do it right. What's the best solution/carb cleaner to soak the carb in? Who makes a quality rebuilt kit? How do you clean the tiny passageways in the carbs? How do you adjust the carb to the correct setting? |
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#10 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Carburetor Woes
For soaking you're going to be limited to what the local autoparts store carries. And I can only find 1-gallon cans these days, which are too small to soak the carb body in (on a Q-Jet anyway, you might get that one in there). The warmer the fluid, the better (but it's flammable, don't be dangerous). In the old days this stuff would strip the minerals out of a skeleton, but now it's environmentally safer. Which is a mixed bag... stuff doesn't work as well anymore, but you old guys didn't have to pour your used motor oil down the storm sewer either :-) At least my Dad flushed it down the toilet...
I think the best rebuild kit is probably the one you can actually find. Tiny passages can be blown out with compressed air. Wear hearing and eye protection. The latter is essential, the former just a good idea. If you can give me the actual model number I've got a decent book that covers 8 or so Rochester carbs, I can probably find initial setup info. And don't throw ANYTHING away until the truck runs right again. It's almost certainly the carb as all above have said, but there's a slim chance it could be a vacuum leak somewhere and 'choking' the motor makes up for it.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#11 | |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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Re: Carburetor Woes
Quote:
all Good Coley ![]()
__________________
....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#12 |
Registered User
Join Date: Nov 2010
Location: Alabama
Posts: 739
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Re: Carburetor Woes
Great, thanks. I'll look for that number.
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#13 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: Carburetor Woes
That old 2 jet, is an easy carb to rebuild....that said, it has a govener, on the side on that big truck....I am damn sure that the carb needs help, after the yrs of sit time.....before you even try to dial the carb, points/condenser ,& timing 1st....dial the carb last
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#14 |
Registered User
Join Date: Nov 2010
Location: Alabama
Posts: 739
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Re: Carburetor Woes
Haven't had a chance to take the carb off yet, but where is the model number located so I'll know where to look?
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#15 |
Registered User
Join Date: Mar 2014
Location: Clearfield Utah
Posts: 638
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Re: Carburetor Woes
I don't remember the 2 brls having a stamped number (I could be wrong) they had a stamped metal tag on one of the top horn screws.
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My build thread. 1977 C10 short box. >>>> http://67-72chevytrucks.com/vboard/s...d.php?t=624182 700R4 build thread. >>> http://67-72chevytrucks.com/vboard/s...36#post6740236 |
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