Carb question

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66corsaguy
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Carb question

Post by 66corsaguy »

I've got 66 corsa 4x1 carbs.
I believe my secondaries are not hooked up. I assumed that meant fuel wouldn't pass thru them. Is that an incorrect assumption? Because my driver side secondary fills with fuel (and leaks due to cork gasket being old)

Understanding primaries: I thought one was used for starting and 1st and 2nd gear and than 2nd was used for 3rd and 4th. Is that false? Are both primaries contributing fuel at all times?

One primary helps with starting (throttle plate) my left primary has a little lock bracket on it to hold it in place. The one on the right does not have this plate connected to the arm and no lock. That's correct? It shouldn't be connected and just stays open?
If so my left primary gets me started with throttle plate? So that would be my primary primary haha

Beginner here. Sorry if this is super basic. Just trying to wrap my head around how these sync


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66corsaguy
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Re: Carb question

Post by 66corsaguy »

Imagethis is left side. Imagethis is my right side. I'm guessing this is connected to gas pedal so this must be the lead primary. But behind it my throttle plate arm is not connected. Is that correct?


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bbodie52
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Re: Carb question

Post by bbodie52 »

All non-turbocharged Corvairs are fitted with the two primary carburetors. They are in operation at all times when the engine is running — from idle to wide-open throttle. The 140 hp engine is the only engine that was fitted with secondary carburetors. These are activated by progressive throttle linkage that only opens them at higher speeds when the engine can take advantage of the additional fuel/air mixture provided by these carburetors. The 140 hp engine was essentially identical to the 110 hp engine, which only had two primary carburetors. The difference with a 140 hp engine was found in the cylinder heads. These heads have larger valves for improved airflow capacity. The intake manifolds were modified with the addition of a second carburetor mounting pad on each intake manifold. Also, a dual exhaust system was fitted to the 140 hp engine to improve breathing on the exhaust side. Since the camshaft was the same as the 110 hp engine, the additional top-end horsepower was all due to the improved breathing possible by doubling the carburetors, increasing the valve size, and improving the exhaust with a dual muffler, dual exhaust system. The secondary carburetors only come into play at high speed driving levels with wide open throttle. (A four barrel carburetor that is commonly found on V-8 engines has a similar arrangement, except that all four carburetors throats are in a single housing — usually with a progressive linkage. Instead of using a single four barrel carburetor, the Corvair uses four one-barrel individual carburetors (with a progressive linkage) that are more appropriate for the physical layout of the flat, opposed six-cylinder Corvair engine.

The progressive linkage found on the 140 hp engines changed in 1966 to include a lockout mechanism that prevented the secondaries from opening until the engine reached normal operating temperatures.

The section of the 1965 Corvair Chassis shop Manual below addresses the secondary carburetors on page 6M-8. It does not cover the 1966 and later carburetor and linkage changes. Those were covered in the 1966 and later supplements, which I do not have.
1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL.pdf
1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL
(8.87 MiB) Downloaded 50 times
That tuneup section of the Corvair shop manual may be helpful to you when tuning and adjusting the carburetors.
1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE TUNE-UP.pdf
1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE TUNE-UP
(2.92 MiB) Downloaded 45 times
The manual below was printed as a supplement to the shop manual. About half of the manual describes the functional operation of each carburetor subsystem. It is very useful to help you understand the functional operation and general theory of the carburetor subsystems. The rest addresses tuning, maintenance and adjustment. Page 12 specifically addresses the 140 hp four carburetor set up.
DELCO ROCHESTER - Models H, HV Carburetor Service Manual.pdf
DELCO ROCHESTER - Models H, HV Carburetor Service Manual
(1.79 MiB) Downloaded 49 times
The Corvair Assembly Manual below provides additional explanation and illustrations that may prove helpful to you. The 140 hp 4×1 carburetor configuration is specifically addressed starting on page 14.
1965 Corvair Assembly Manual - CARBURETOR & FUEL SYSTEM.pdf
1965 Corvair Assembly Manual - CARBURETOR & FUEL SYSTEM
(3.92 MiB) Downloaded 58 times
I hope that the above information is helpful to you. Please let us know if you need any clarification or further explanation.
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
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66corsaguy
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Re: Carb question

Post by 66corsaguy »

Thank you I will read all that you have forwarded and I also have the shop manual and supplement
Sometimes it feels like I am reading Greek but I know Once it clicks it will all make sense.

I bought this car two years ago and already know so much more about it than I did when I first got it. After a horrible experience with SF corvair mechanic I decided to learn and do what I can and with this forum I've learned it's possible so I am starting at the beginning.






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drb930
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Re: Carb question

Post by drb930 »

bbodie52 wrote: Sat May 20, 2017 2:31 pm All non-turbocharged Corvairs are fitted with the two primary carburetors. They are in operation at all times when the engine is running — from idle to wide-open throttle. The 140 hp engine is the only engine that was fitted with secondary carburetors. These are activated by progressive throttle linkage that only opens them at higher speeds when the engine can take advantage of the additional fuel/air mixture provided by these carburetors. The 140 hp engine was essentially identical to the 110 hp engine, which only had two primary carburetors. The difference with a 140 hp engine was found in the cylinder heads. These heads have larger valves for improved airflow capacity. The intake manifolds were modified with the addition of a second carburetor mounting pad on each intake manifold. Also, a dual exhaust system was fitted to the 140 hp engine to improve breathing on the exhaust side. Since the camshaft was the same as the 110 hp engine, the additional top-end horsepower was all due to the improved breathing possible by doubling the carburetors, increasing the valve size, and improving the exhaust with a dual muffler, dual exhaust system. The secondary carburetors only come into play at high speed driving levels with wide open throttle. (A four barrel carburetor that is commonly found on V-8 engines has a similar arrangement, except that all four carburetors throats are in a single housing — usually with a progressive linkage. Instead of using a single four barrel carburetor, the Corvair uses four one-barrel individual carburetors (with a progressive linkage) that are more appropriate for the physical layout of the flat, opposed six-cylinder Corvair engine.

The progressive linkage found on the 140 hp engines changed in 1966 to include a lockout mechanism that prevented the secondaries from opening until the engine reached normal operating temperatures.

The section of the 1965 Corvair Chassis shop Manual below addresses the secondary carburetors on page 6M-8. It does not cover the 1966 and later carburetor and linkage changes. Those were covered in the 1966 and later supplements, which I do not have.
1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL.pdf

That tuneup section of the Corvair shop manual may be helpful to you when tuning and adjusting the carburetors.
1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE TUNE-UP.pdf

The manual below was printed as a supplement to the shop manual. About half of the manual describes the functional operation of each carburetor subsystem. It is very useful to help you understand the functional operation and general theory of the carburetor subsystems. The rest addresses tuning, maintenance and adjustment. Page 12 specifically addresses the 140 hp four carburetor set up.
DELCO ROCHESTER - Models H, HV Carburetor Service Manual.pdf

The Corvair Assembly Manual below provides additional explanation and illustrations that may prove helpful to you. The 140 hp 4×1 carburetor configuration is specifically addressed starting on page 14.
1965 Corvair Assembly Manual - CARBURETOR & FUEL SYSTEM.pdf

I hope that the above information is helpful to you. Please let us know if you need any clarification or further explanation.
Thanks for all you have already posted on this.
Would you happen to have the 68 & 69 assembly manuals?
I'm trying to figure out the secondary linkages on a 69 140.

Thanks,
Dave
steve57
Posts: 282
Joined: Tue Sep 23, 2014 5:40 pm

Re: Carb question

Post by steve57 »

Here you go Dave, from the 69 assembly manual.
615E399F-7ACE-4084-B0A3-587B30F7AA03.jpeg
8A346134-F375-4AC7-8AB9-CB3A74C8CA5C.jpeg
3376460E-453A-4DBD-B377-73F252BB7921.jpeg
AB4A77F8-81EB-4D6E-82E3-9D7595A7F63B.jpeg
Steve
Bakersfield,CA
1969 monza coupe
110, 4speed
drb930
Posts: 8
Joined: Thu Feb 25, 2021 11:04 pm
Location: Los Angeles / SLO

Re: Carb question

Post by drb930 »

steve57 wrote: Wed Jun 30, 2021 7:14 pm Here you go Dave, from the 69 assembly manual.615E399F-7ACE-4084-B0A3-587B30F7AA03.jpeg8A346134-F375-4AC7-8AB9-CB3A74C8CA5C.jpeg3376460E-453A-4DBD-B377-73F252BB7921.jpegAB4A77F8-81EB-4D6E-82E3-9D7595A7F63B.jpeg
Steve, thanks so much!
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