Quadrajet advice
Thread Starter
Melting Slicks
Joined: Apr 2010
Posts: 2,793
Likes: 1,192
From: Canberra Australia
2025 C3 of the Year Finalist - Modified
Quadrajet advice
Hi
My 71 350/270 auto is fitted with the following Quadrajet
7041211 (0966 this part is hard to read)
From my checking this is not the correct carb and possibly one built in later years to be used as spare parts.
I think I should have had a 7041212.
My problem is that the car is hard to start cold and can result in what appears to be flooding and running like its lost a number of cylinders for the fist minute or so.
I looked at the choke and when cold it is almost completely closed. (open it up by hand and it starts a bit better).
It opens fully when warm.
After reading the shop manual etc and the docs by Lars I have just got more confused as I cant see how the version I have with the choke linkages etc does what is described.
There seems to be no linkage from what I can see between the choke and the vacuum secondary solenoid.
Also the solenoid obviously has some form of bleed down but I cant get it to travel more than half way in using a hand vacuum pump (so it is probably bad).
Sorry if this is too simple but i am fairly new to this.
Am I missing some parts or am I missing something :-)
Regards
Craig
My 71 350/270 auto is fitted with the following Quadrajet
7041211 (0966 this part is hard to read)
From my checking this is not the correct carb and possibly one built in later years to be used as spare parts.
I think I should have had a 7041212.
My problem is that the car is hard to start cold and can result in what appears to be flooding and running like its lost a number of cylinders for the fist minute or so.
I looked at the choke and when cold it is almost completely closed. (open it up by hand and it starts a bit better).
It opens fully when warm.
After reading the shop manual etc and the docs by Lars I have just got more confused as I cant see how the version I have with the choke linkages etc does what is described.
There seems to be no linkage from what I can see between the choke and the vacuum secondary solenoid.
Also the solenoid obviously has some form of bleed down but I cant get it to travel more than half way in using a hand vacuum pump (so it is probably bad).
Sorry if this is too simple but i am fairly new to this.
Am I missing some parts or am I missing something :-)
Regards
Craig
Pro
Joined: Jan 2010
Posts: 533
Likes: 18
From: Boca Raton Florida
Apparently more than one Corvette has had the 7041211 carb installed. Corvette Fever ran an article earlier this year on rebuilding yours:
http://www.corvettefever.com/techart...ild/index.html
If you want to go beyone the Corvette Fever level of detail, there are several excellent books that cover the Quadrajet. Cliff Ruggles' How to Rebuild and Modify Rochester Quadrajet Carburetors is one. Doug Roe's Rochester Carburetors is also informative. Mike Stubblefield and John Haynes produced The Haynes Rochester Carburetor Manual.
The first author (Cliff Ruggles) has a web site where you can ask your questions.
http://www.cliffshighperformance.com/parts.html
I know only enough to mess up a Quadrajet so I look to these sources for information and advice.
http://www.corvettefever.com/techart...ild/index.html
If you want to go beyone the Corvette Fever level of detail, there are several excellent books that cover the Quadrajet. Cliff Ruggles' How to Rebuild and Modify Rochester Quadrajet Carburetors is one. Doug Roe's Rochester Carburetors is also informative. Mike Stubblefield and John Haynes produced The Haynes Rochester Carburetor Manual.
The first author (Cliff Ruggles) has a web site where you can ask your questions.
http://www.cliffshighperformance.com/parts.html
I know only enough to mess up a Quadrajet so I look to these sources for information and advice.
Burning Brakes
Joined: May 2009
Posts: 850
Likes: 36
From: Providence RI
The choke pulloff looks like it might be installed twisted 180ş- the vacuum tube usually points right at the port on the front of the carburetor, rather than away from it as yours does.
That pulloff isn't directly linked to the choke; rather, it pulls the choke open by contacting one of the arms on the choke-lever.
Your carb is probably due for a cleaning and rebuild, at which point you can check and correct the operation of all systems (and replace the rubber fuel-feed line with some properly-bent hard-line with flared connections).
That pulloff isn't directly linked to the choke; rather, it pulls the choke open by contacting one of the arms on the choke-lever.
Your carb is probably due for a cleaning and rebuild, at which point you can check and correct the operation of all systems (and replace the rubber fuel-feed line with some properly-bent hard-line with flared connections).
Burning Brakes
Joined: May 2009
Posts: 850
Likes: 36
From: Providence RI
If the jetting on this carb is stock, then the secondaries would be different from the 212 carb, but the primaries would differ with the main metering rod being slightly richer, but the main jet being the same.
Burning Brakes
Joined: May 2009
Posts: 850
Likes: 36
From: Providence RI
Not according to the AC-Delco carburetor listing book or the Corvette Black Book; they list them as the 7041212 and 7041213, respectively.
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,361
From: At my Bar drinking and wrenching in Lafayette Colorado
The carb is a 1971 1/2-ton truck carb, and it will run just fine on your Vette. Simply set the carb up as outlined in the "Quickie Performance Setup" section of my paper and you will get outstanding performance from it.
You are missing 2 pieces of choke linkage on your carb: There should be a short piece that goes into the lower slot in the choke pulloff lever, connecting it to the rest of the linkage, and your upper piece is incorrect for the year and must be replaced. Once you install the correct choke pieces, set the choke up per the Choke Setup section of my paper and it will run fine.
Carb numbers and applications of interest for 1971 are as follows:
7041200 CHEV 71 CHEVELLE 402/454 AUTO
7041201 CHEV 71 CHEVELLE 402/454 MAN
7041202 CHEV 71 CHEVELLE 350 AUTO
7041203 CHEV 71 CHEVELLE 350 MAN
7041204 Chev 71 454 AT VETTE
7041205 Chev 71 454 MT VETTE
7041206 CHEV 71 402 SERIES 20 & 30 TRUCK
7041208 CHEV 71 350 SERIES 20 & 30 TRUCK
7041209 CHEV 71 402 SERIES 10 TRUCK
7041211 CHEV 71 350 SERIES 10 TRUCK
7041212 CHEV 71 Vette 350 A/T
7041213 CHEV 71 Vette 350 M/T
Lars
You are missing 2 pieces of choke linkage on your carb: There should be a short piece that goes into the lower slot in the choke pulloff lever, connecting it to the rest of the linkage, and your upper piece is incorrect for the year and must be replaced. Once you install the correct choke pieces, set the choke up per the Choke Setup section of my paper and it will run fine.
Carb numbers and applications of interest for 1971 are as follows:
7041200 CHEV 71 CHEVELLE 402/454 AUTO
7041201 CHEV 71 CHEVELLE 402/454 MAN
7041202 CHEV 71 CHEVELLE 350 AUTO
7041203 CHEV 71 CHEVELLE 350 MAN
7041204 Chev 71 454 AT VETTE
7041205 Chev 71 454 MT VETTE
7041206 CHEV 71 402 SERIES 20 & 30 TRUCK
7041208 CHEV 71 350 SERIES 20 & 30 TRUCK
7041209 CHEV 71 402 SERIES 10 TRUCK
7041211 CHEV 71 350 SERIES 10 TRUCK
7041212 CHEV 71 Vette 350 A/T
7041213 CHEV 71 Vette 350 M/T
Lars
Last edited by lars; Jul 10, 2010 at 12:44 PM.
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Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,361
From: At my Bar drinking and wrenching in Lafayette Colorado
Here you go....
I just went out and grabbed a 1971 carb out of my Barrel-O-Parts: This carb has the correct choke pieces correctly installed. You need to obtain the parts to make your carb look like this (less the dirt and corrosion...). Do note that this carb is missing the coiled spring that should be installed around the pulloff lever, pushing the lower rod to the left (your carb has the spring, but is missing the rod). Your carb also has the wrong choke attach lever installed - note that the lever must have 2 holes in it: One slotted hole for the choke rod coming from the divorced choke, and one for the short lower pulloff rod:
Lars
I just went out and grabbed a 1971 carb out of my Barrel-O-Parts: This carb has the correct choke pieces correctly installed. You need to obtain the parts to make your carb look like this (less the dirt and corrosion...). Do note that this carb is missing the coiled spring that should be installed around the pulloff lever, pushing the lower rod to the left (your carb has the spring, but is missing the rod). Your carb also has the wrong choke attach lever installed - note that the lever must have 2 holes in it: One slotted hole for the choke rod coming from the divorced choke, and one for the short lower pulloff rod:
Lars
Last edited by lars; Jul 10, 2010 at 12:42 PM.
Thread Starter
Melting Slicks
Joined: Apr 2010
Posts: 2,793
Likes: 1,192
From: Canberra Australia
2025 C3 of the Year Finalist - Modified
Thanks for the advice everyone.
Pleased that I was not going mad :-)
So what I need is -
- replacement choke attach lever (2 holes) (attached to backing bracket)
- replacement short choke rod
- replacement vacuum choke pull off.
I can find the rods and choke pull off online but the correct attach lever and backing bracket may be a bit harder.
Any advice on where I could get that would be appreciated.
Please note I am in Australia so finding it in a junk yard etc is less likely.
Regards
Craig
Pleased that I was not going mad :-)
So what I need is -
- replacement choke attach lever (2 holes) (attached to backing bracket)
- replacement short choke rod
- replacement vacuum choke pull off.
I can find the rods and choke pull off online but the correct attach lever and backing bracket may be a bit harder.
Any advice on where I could get that would be appreciated.
Please note I am in Australia so finding it in a junk yard etc is less likely.
Regards
Craig
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,361
From: At my Bar drinking and wrenching in Lafayette Colorado
All and any of my papers are available directly from me by e-mail request:
V8FastCars@msn.com
State which paper(s) you want so I don't send you the Mitsubishi how-to papers.
Note that I do not post any of my papers on-line, and any of my papers posted by others tend to be obsolete and outdated - don't download them or use them if found on-line.
Lars
Thread Starter
Melting Slicks
Joined: Apr 2010
Posts: 2,793
Likes: 1,192
From: Canberra Australia
2025 C3 of the Year Finalist - Modified
I thought the pulloff would need replacing as it does not fully retract if I suck on its hose or use a vacuum pump.
Craig
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,361
From: At my Bar drinking and wrenching in Lafayette Colorado
If the pulloff is defective or inoperable you need to replace it. However, it is seldom that the failure mode involves only partial retraction - when the pulloff fails, it either leaks and fails to retract at all, or seizes up so no movement is possible. The fact that you indicate that it partially retracts is indicative that it is restricted in its movement: It is likely that the incorrect linkage is limiting its movement (notice how the Bubba-installed and custom bent linkage piece is at the center of the slot travel in the pulloff, which will only allow the pulloff to move half its intended travel distance). Remove the incorrect linkage and then test the pulloff to see if it's operable. Then, throw that linkage in the trash and install the right parts...
Lars
Lars
Last edited by lars; Jul 10, 2010 at 09:38 PM.
