Secondary carb internal components image

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66corsaguy
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Secondary carb internal components image

Post by 66corsaguy »

Hey everyone

I am rebuilding my carbs on my 66 Corsa. The primaries are done but my secondaries were not being used and possibly missing a few parts

Does anyone have an image breakdown of the secondaries? An exploded view would be perfect so I can make sure I have everything needed internally.
Thanks
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Re: Secondary carb internal components image

Post by bbodie52 »

The 1965 Corvair Chassis Shop Manual and the DELCO ROCHESTER - Models H, HV Carburetor Service Manual (attached) should provide you with much of what you need. The latter is a great supplement to the shop manual, and describes the functional operation and differences between each version of the carburetors.
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DELCO ROCHESTER - Models H, HV Carburetor Service Manual.pdf
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1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL.pdf
1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL
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Brad Bodie
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Re: Secondary carb internal components image

Post by 66vairguy »

You'd think the secondaries are simple, but GM revised them several times to correct issues. Most issue can be avoided by doing three things - If you open the secondaries KEEP them open at least a second to prevent fuel accumulation on the throttle plate that will make it sticky. Don't open the secondaries when the engine is cold. Do use the secondaries occasionally to flow new fuel into them (certainly not an issue for some of us).

The 66 linkage is complex, many just use the 65 style linkage.

I'd also suggest a very good carburetor book by Bob Helt at Clark's -- http://www.corvair.com/user-cgi/search.cgi?part=C3939
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Re: Secondary carb internal components image

Post by 66corsaguy »

66vairguy wrote:You'd think the secondaries are simple, but GM revised them several times to correct issues. Most issue can be avoided by doing three things - If you open the secondaries KEEP them open at least a second to prevent fuel accumulation on the throttle plate that will make it sticky. Don't open the secondaries when the engine is cold. Do use the secondaries occasionally to flow new fuel into them (certainly not an issue for some of us).

The 66 linkage is complex, many just use the 65 style linkage.

I'd also suggest a very good carburetor book by Bob Helt at Clark's -- http://www.corvair.com/user-cgi/search.cgi?part=C3939
I have the bob helt book but he doesn't go into as much detail of the parts that go inside the carb for secondaries. A lot less than the primary carbs.




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Re: Secondary carb internal components image

Post by 66corsaguy »

bbodie52 wrote:The 1965 Corvair Chassis Shop Manual and the DELCO ROCHESTER - Models H, HV Carburetor Service Manual (attached) should provide you with much of what you need. The latter is a great supplement to the shop manual, and describes the functional operation and differences between each version of the carburetors.
Thanks for this but I've looked for info throughout these a number of times and see nothing about the parts in the secondaries.
No exploded view. I have bob helt book and nothing in there either.




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Re: Secondary carb internal components image

Post by Wagon Master »

In the second manual Brad posted for you, starting on page 6M-8, it covers service of the model H carbs. Including exploded views.
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Re: Secondary carb internal components image

Post by 66corsaguy »

Wagon Master wrote:In the second manual Brad posted for you, starting on page 6M-8, it covers service of the model H carbs. Including exploded views.
Hmm. Well I guess it doesn't show what would be replaced in terms internal parts. I think there's one that goes in the hole where the U shape is. But I'm not positive. Beyond that - are there any other jets that need to be replaced. The primary gets 3 replacement brass things internally (like a .22 cal bullet) I am assuming than the secondary only gets the 2. (One under the float spring the other next to the U shape)


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Re: Secondary carb internal components image

Post by bbodie52 »

It sounds like you're making too big a thing of the secondary carburetors. The secondaries are essentially a subset of the primary carburetors. As it states on page 6M–8 of the 1965 Corvair Chassis Shop Manual, "The Rochester H carburetor is used as a secondary carburetor on the Corvair 10700 series (4×1 carburetors)… Has no choke, idle, power enrichment or low-speed circuits".

While it has no choke or idle circuits, it still has a float bowl and floats which require the replacement of the needle and seat assembly and adjustment of the float height and float drop (just like the primaries). Of course, all of the gaskets are changed out in the metal carburetor components should be soaked in carburetor cleaner solution and thoroughly rinsed and dried. The accelerator pump assembly is retained, since its mechanism and spring assembly is used to help put spring tension on the throttle butterfly to keep it closed. The lack of power enrichment and low-speed circuits does not change anything that would be swapped out from a rebuild kit. The fuel inlet gaskets and filter are the same as the primaries. Everything that is illustrated in figure 20 (Bowl Cover – Exploded View) is essentially identical between the secondaries and primaries, with the exception of the missing choke butterfly that is not a part of the secondary carburetors. Cleaning and inspection of the secondary carburetors is described in detail in the paragraphs following figure 20. Of the items shown in figure 21, I believe that items 11, 12 and 13 are the only things you will find in the rebuild kit that are replaced in the carburetor body. It is not necessary to remove item 14 (main metering jet) or the retaining screws (item 8) that hold the throttle butterfly valve in place. In fact, the main metering jet is a brass component that is often tight and difficult to unscrew, and might be damaged if you attempt to remove it. Carburetor parts dip cleaning fluid will still be able to enter the carburetor passages with the jet in place. Attempting to remove the throttle valve retaining screws from the carburetor body or the choke valve retaining screws from the bowl cover is usually not recommended as a part of the cleaning process. The threads on the screws are staked at the factory to prevent them from accidentally coming loose and potentially being sucked into the engine intake. To remove the screws it is necessary to grind off the threads at the end to remove the staked portion so that the screws can be removed. Once this is done, new screws need to be purchased to replace the old screws, and the threads must be staked as they were at the factory to ensure that the screws do not come loose because of engine vibration.

Not all carburetor rebuild kits are identical. The components that are included are usually made of rubber or gasket material, or have a tendency to wear. Just match them up and replace them after soaking the metal carburetor components in carburetor parts dip and rinsing and drying the carburetor components prior to reassembly.

In addition to the carburetor rebuild kits, you may wish to purchase four of the thick insulator spacers to replace the old ones. These spacers can become brittle and may be damaged when removed. Reusing damaged spacers could create a vacuum leak, and omitting them can cause the carburetors to transfer too much heat from the intake manifold, which can cause the gasoline to boil and vaporize within the carburetor body. In addition to the spacers, a carburetor base gasket should be installed above and below the spacer to sandwich the components in a way that will form a proper seal and eliminate the possibility of a vacuum leak. Replacing the carburetor inlet filter "stones" during the carburetor rebuild may also be advisable, and these are not included with most rebuild kits.

ImageImage

The combination of the Rochester carburetor manual and the factory shop manual does a pretty good job of describing and illustrating the components of the Corvair Rochester carburetors. The first half of the Delco Rochester carburetor manual does a very good job of describing carburetor operation and the function of the various components that make up the Corvair carburetor. It is worthwhile taking the time to read through this manual so that you can gain a good understanding of the function of these carburetors — knowledge that can help you in the future with tuning and troubleshooting carburetors on the Corvair. The Rochester H and HV carburetors are not complicated or difficult to rebuild. But mistakes with improper or incomplete cleaning or improper assembly and adjustment can cause problems when driving the car that may require a second effort to get the carburetors right. It is better to take your time and read the material available to you to get the job done correctly the first time.

The secondary carburetors on the 140 hp engine often see little use. Quite often only the primaries are in operation for perhaps 90% or more of engine operation (depending on the driver behavior). The lack of use of the secondaries can cause problems because of their inactivity. The throttle mechanism, as mentioned earlier, can get gummed up with lack of use, and may stick partially open, since only the spring in the accelerator pump provides any spring tension to close the throttle in the secondaries. The fuel in the float bowl can also become stale and can even evaporate to the point where it forms deposits in the fuel passageways inside the carburetor that can hinder proper operation. If the throttle sticks partially open and does not close completely this amounts to a vacuum leak that can cause a lean mixture by permitting too much air into the intake manifold to thin the fuel air mixture that is provided by the primary carburetors. If you're aware of these potential problems you can adjust your driving habits to engage the secondary carburetors more frequently to try to keep them in proper operation and avoid problems that can occur from the secondaries being idle and unused for long periods. You can also use carburetor cleaning spray to remove deposits from around the secondary throttle butterfly in each carburetor as a part of your tuneup procedure. This can help to ensure smooth operation of the secondary carburetor throttle butterflies.
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Re: Secondary carb internal components image

Post by 66vairguy »

As Brad said - Basically a secondary is a primary carb without some features.

Per respected Steve Goodman I've installed 62-63 primary bases under the secondary tops and used the solid secondary throttle plate (no transition slot). These simple primaries make good replacements bases for secondaries that are damaged or missing parts. Adjust the throttle plate so it is closed and set the idle mixture to half the turns out vs. the primary.

Note the later secondaries had a FIXED idle circuit unlike the early versions. It's all in Bob Helt's book as are the recommended jet sizes.

I take one exception with Bob Helt's book - do not increase the jet sizes as he suggests. Even today's fuel works fine with the stock jets, however if your car is at sea level and operated in hot climates going up one size may help keep the heads cooler. Too large a jet size will carbon up the heads and piston rings.
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Re: Secondary carb internal components image

Post by 66corsaguy »

bbodie52 wrote:It sounds like you're making too big a thing of the secondary carburetors. The secondaries are essentially a subset of the primary carburetors. As it states on page 6M–8 of the 1965 Corvair Chassis Shop Manual, "The Rochester H carburetor is used as a secondary carburetor on the Corvair 10700 series (4×1 carburetors)… Has no choke, idle, power enrichment or low-speed circuits".

While it has no choke or idle circuits, it still has a float bowl and floats which require the replacement of the needle and seat assembly and adjustment of the float height and float drop (just like the primaries). Of course, all of the gaskets are changed out in the metal carburetor components should be soaked in carburetor cleaner solution and thoroughly rinsed and dried. The accelerator pump assembly is retained, since its mechanism and spring assembly is used to help put spring tension on the throttle butterfly to keep it closed. The lack of power enrichment and low-speed circuits does not change anything that would be swapped out from a rebuild kit. The fuel inlet gaskets and filter are the same as the primaries. Everything that is illustrated in figure 20 (Bowl Cover – Exploded View) is essentially identical between the secondaries and primaries, with the exception of the missing choke butterfly that is not a part of the secondary carburetors. Cleaning and inspection of the secondary carburetors is described in detail in the paragraphs following figure 20. Of the items shown in figure 21, I believe that items 11, 12 and 13 are the only things you will find in the rebuild kit that are replaced in the carburetor body. It is not necessary to remove item 14 (main metering jet) or the retaining screws (item 8) that hold the throttle butterfly valve in place. In fact, the main metering jet is a brass component that is often tight and difficult to unscrew, and might be damaged if you attempt to remove it. Carburetor parts dip cleaning fluid will still be able to enter the carburetor passages with the jet in place. Attempting to remove the throttle valve retaining screws from the carburetor body or the choke valve retaining screws from the bowl cover is usually not recommended as a part of the cleaning process. The threads on the screws are staked at the factory to prevent them from accidentally coming loose and potentially being sucked into the engine intake. To remove the screws it is necessary to grind off the threads at the end to remove the staked portion so that the screws can be removed. Once this is done, new screws need to be purchased to replace the old screws, and the threads must be staked as they were at the factory to ensure that the screws do not come loose because of engine vibration.

Not all carburetor rebuild kits are identical. The components that are included are usually made of rubber or gasket material, or have a tendency to wear. Just match them up and replace them after soaking the metal carburetor components in carburetor parts dip and rinsing and drying the carburetor components prior to reassembly.

In addition to the carburetor rebuild kits, you may wish to purchase four of the thick insulator spacers to replace the old ones. These spacers can become brittle and may be damaged when removed. Reusing damaged spacers could create a vacuum leak, and omitting them can cause the carburetors to transfer too much heat from the intake manifold, which can cause the gasoline to boil and vaporize within the carburetor body. In addition to the spacers, a carburetor base gasket should be installed above and below the spacer to sandwich the components in a way that will form a proper seal and eliminate the possibility of a vacuum leak. Replacing the carburetor inlet filter "stones" during the carburetor rebuild may also be advisable, and these are not included with most rebuild kits.

ImageImage

The combination of the Rochester carburetor manual and the factory shop manual does a pretty good job of describing and illustrating the components of the Corvair Rochester carburetors. The first half of the Delco Rochester carburetor manual does a very good job of describing carburetor operation and the function of the various components that make up the Corvair carburetor. It is worthwhile taking the time to read through this manual so that you can gain a good understanding of the function of these carburetors — knowledge that can help you in the future with tuning and troubleshooting carburetors on the Corvair. The Rochester H and HV carburetors are not complicated or difficult to rebuild. But mistakes with improper or incomplete cleaning or improper assembly and adjustment can cause problems when driving the car that may require a second effort to get the carburetors right. It is better to take your time and read the material available to you to get the job done correctly the first time.

The secondary carburetors on the 140 hp engine often see little use. Quite often only the primaries are in operation for perhaps 90% or more of engine operation (depending on the driver behavior). The lack of use of the secondaries can cause problems because of their inactivity. The throttle mechanism, as mentioned earlier, can get gummed up with lack of use, and may stick partially open, since only the spring in the accelerator pump provides any spring tension to close the throttle in the secondaries. The fuel in the float bowl can also become stale and can even evaporate to the point where it forms deposits in the fuel passageways inside the carburetor that can hinder proper operation. If the throttle sticks partially open and does not close completely this amounts to a vacuum leak that can cause a lean mixture by permitting too much air into the intake manifold to thin the fuel air mixture that is provided by the primary carburetors. If you're aware of these potential problems you can adjust your driving habits to engage the secondary carburetors more frequently to try to keep them in proper operation and avoid problems that can occur from the secondaries being idle and unused for long periods. You can also use carburetor cleaning spray to remove deposits from around the secondary throttle butterfly in each carburetor as a part of your tuneup procedure. This can help to ensure smooth operation of the secondary carburetor throttle butterflies.
Thank you for this. It is possible I may be over thinking. I just want to make sure I put all the proper parts in since problem solving later may be a Pain with all the changes I am making and the lack of experience I have with any motor. But I am also a perfectionist!

I have all new gaskets including the thick one on the base to sandwich. My float though was absorbing gas so I am buying a new one and waiting for that than close up.

Unfortunately I live in a city and the only way to get those secondaries open is to hit the freeway, which I will do.

Thanks to both and all for the detailed info that I will reference for years to come and I hope it's helpful to others.



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Re: Secondary carb internal components image

Post by 66corsaguy »

bbodie52 wrote:It sounds like you're making too big a thing of the secondary carburetors. The secondaries are essentially a subset of the primary carburetors. As it states on page 6M–8 of the 1965 Corvair Chassis Shop Manual, "The Rochester H carburetor is used as a secondary carburetor on the Corvair 10700 series (4×1 carburetors)… Has no choke, idle, power enrichment or low-speed circuits".

While it has no choke or idle circuits, it still has a float bowl and floats which require the replacement of the needle and seat assembly and adjustment of the float height and float drop (just like the primaries). Of course, all of the gaskets are changed out in the metal carburetor components should be soaked in carburetor cleaner solution and thoroughly rinsed and dried. The accelerator pump assembly is retained, since its mechanism and spring assembly is used to help put spring tension on the throttle butterfly to keep it closed. The lack of power enrichment and low-speed circuits does not change anything that would be swapped out from a rebuild kit. The fuel inlet gaskets and filter are the same as the primaries. Everything that is illustrated in figure 20 (Bowl Cover – Exploded View) is essentially identical between the secondaries and primaries, with the exception of the missing choke butterfly that is not a part of the secondary carburetors. Cleaning and inspection of the secondary carburetors is described in detail in the paragraphs following figure 20. Of the items shown in figure 21, I believe that items 11, 12 and 13 are the only things you will find in the rebuild kit that are replaced in the carburetor body. It is not necessary to remove item 14 (main metering jet) or the retaining screws (item 8) that hold the throttle butterfly valve in place. In fact, the main metering jet is a brass component that is often tight and difficult to unscrew, and might be damaged if you attempt to remove it. Carburetor parts dip cleaning fluid will still be able to enter the carburetor passages with the jet in place. Attempting to remove the throttle valve retaining screws from the carburetor body or the choke valve retaining screws from the bowl cover is usually not recommended as a part of the cleaning process. The threads on the screws are staked at the factory to prevent them from accidentally coming loose and potentially being sucked into the engine intake. To remove the screws it is necessary to grind off the threads at the end to remove the staked portion so that the screws can be removed. Once this is done, new screws need to be purchased to replace the old screws, and the threads must be staked as they were at the factory to ensure that the screws do not come loose because of engine vibration.

Not all carburetor rebuild kits are identical. The components that are included are usually made of rubber or gasket material, or have a tendency to wear. Just match them up and replace them after soaking the metal carburetor components in carburetor parts dip and rinsing and drying the carburetor components prior to reassembly.

In addition to the carburetor rebuild kits, you may wish to purchase four of the thick insulator spacers to replace the old ones. These spacers can become brittle and may be damaged when removed. Reusing damaged spacers could create a vacuum leak, and omitting them can cause the carburetors to transfer too much heat from the intake manifold, which can cause the gasoline to boil and vaporize within the carburetor body. In addition to the spacers, a carburetor base gasket should be installed above and below the spacer to sandwich the components in a way that will form a proper seal and eliminate the possibility of a vacuum leak. Replacing the carburetor inlet filter "stones" during the carburetor rebuild may also be advisable, and these are not included with most rebuild kits.

ImageImage

The combination of the Rochester carburetor manual and the factory shop manual does a pretty good job of describing and illustrating the components of the Corvair Rochester carburetors. The first half of the Delco Rochester carburetor manual does a very good job of describing carburetor operation and the function of the various components that make up the Corvair carburetor. It is worthwhile taking the time to read through this manual so that you can gain a good understanding of the function of these carburetors — knowledge that can help you in the future with tuning and troubleshooting carburetors on the Corvair. The Rochester H and HV carburetors are not complicated or difficult to rebuild. But mistakes with improper or incomplete cleaning or improper assembly and adjustment can cause problems when driving the car that may require a second effort to get the carburetors right. It is better to take your time and read the material available to you to get the job done correctly the first time.

The secondary carburetors on the 140 hp engine often see little use. Quite often only the primaries are in operation for perhaps 90% or more of engine operation (depending on the driver behavior). The lack of use of the secondaries can cause problems because of their inactivity. The throttle mechanism, as mentioned earlier, can get gummed up with lack of use, and may stick partially open, since only the spring in the accelerator pump provides any spring tension to close the throttle in the secondaries. The fuel in the float bowl can also become stale and can even evaporate to the point where it forms deposits in the fuel passageways inside the carburetor that can hinder proper operation. If the throttle sticks partially open and does not close completely this amounts to a vacuum leak that can cause a lean mixture by permitting too much air into the intake manifold to thin the fuel air mixture that is provided by the primary carburetors. If you're aware of these potential problems you can adjust your driving habits to engage the secondary carburetors more frequently to try to keep them in proper operation and avoid problems that can occur from the secondaries being idle and unused for long periods. You can also use carburetor cleaning spray to remove deposits from around the secondary throttle butterfly in each carburetor as a part of your tuneup procedure. This can help to ensure smooth operation of the secondary carburetor throttle butterflies.
Thank you for this. It is possible I may be over thinking. I just want to make sure I put all the proper parts in since problem solving later may be a Pain with all the changes I am making and the lack of experience I have with any motor. But I am also a perfectionist!

I have all new gaskets including the thick one on the base to sandwich. My float though was absorbing gas so I am buying a new one and waiting for that than close up.

Unfortunately I live in a city and the only way to get those secondaries open is to hit the freeway, which I will do.

Thanks to both and all for the detailed info that I will reference for years to come and I hope it's helpful to others.



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66corsaguy
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Re: Secondary carb internal components image

Post by 66corsaguy »

bbodie52 wrote:It sounds like you're making too big a thing of the secondary carburetors. The secondaries are essentially a subset of the primary carburetors. As it states on page 6M–8 of the 1965 Corvair Chassis Shop Manual, "The Rochester H carburetor is used as a secondary carburetor on the Corvair 10700 series (4×1 carburetors)… Has no choke, idle, power enrichment or low-speed circuits".

While it has no choke or idle circuits, it still has a float bowl and floats which require the replacement of the needle and seat assembly and adjustment of the float height and float drop (just like the primaries). Of course, all of the gaskets are changed out in the metal carburetor components should be soaked in carburetor cleaner solution and thoroughly rinsed and dried. The accelerator pump assembly is retained, since its mechanism and spring assembly is used to help put spring tension on the throttle butterfly to keep it closed. The lack of power enrichment and low-speed circuits does not change anything that would be swapped out from a rebuild kit. The fuel inlet gaskets and filter are the same as the primaries. Everything that is illustrated in figure 20 (Bowl Cover – Exploded View) is essentially identical between the secondaries and primaries, with the exception of the missing choke butterfly that is not a part of the secondary carburetors. Cleaning and inspection of the secondary carburetors is described in detail in the paragraphs following figure 20. Of the items shown in figure 21, I believe that items 11, 12 and 13 are the only things you will find in the rebuild kit that are replaced in the carburetor body. It is not necessary to remove item 14 (main metering jet) or the retaining screws (item 8) that hold the throttle butterfly valve in place. In fact, the main metering jet is a brass component that is often tight and difficult to unscrew, and might be damaged if you attempt to remove it. Carburetor parts dip cleaning fluid will still be able to enter the carburetor passages with the jet in place. Attempting to remove the throttle valve retaining screws from the carburetor body or the choke valve retaining screws from the bowl cover is usually not recommended as a part of the cleaning process. The threads on the screws are staked at the factory to prevent them from accidentally coming loose and potentially being sucked into the engine intake. To remove the screws it is necessary to grind off the threads at the end to remove the staked portion so that the screws can be removed. Once this is done, new screws need to be purchased to replace the old screws, and the threads must be staked as they were at the factory to ensure that the screws do not come loose because of engine vibration.

Not all carburetor rebuild kits are identical. The components that are included are usually made of rubber or gasket material, or have a tendency to wear. Just match them up and replace them after soaking the metal carburetor components in carburetor parts dip and rinsing and drying the carburetor components prior to reassembly.

In addition to the carburetor rebuild kits, you may wish to purchase four of the thick insulator spacers to replace the old ones. These spacers can become brittle and may be damaged when removed. Reusing damaged spacers could create a vacuum leak, and omitting them can cause the carburetors to transfer too much heat from the intake manifold, which can cause the gasoline to boil and vaporize within the carburetor body. In addition to the spacers, a carburetor base gasket should be installed above and below the spacer to sandwich the components in a way that will form a proper seal and eliminate the possibility of a vacuum leak. Replacing the carburetor inlet filter "stones" during the carburetor rebuild may also be advisable, and these are not included with most rebuild kits.

ImageImage

The combination of the Rochester carburetor manual and the factory shop manual does a pretty good job of describing and illustrating the components of the Corvair Rochester carburetors. The first half of the Delco Rochester carburetor manual does a very good job of describing carburetor operation and the function of the various components that make up the Corvair carburetor. It is worthwhile taking the time to read through this manual so that you can gain a good understanding of the function of these carburetors — knowledge that can help you in the future with tuning and troubleshooting carburetors on the Corvair. The Rochester H and HV carburetors are not complicated or difficult to rebuild. But mistakes with improper or incomplete cleaning or improper assembly and adjustment can cause problems when driving the car that may require a second effort to get the carburetors right. It is better to take your time and read the material available to you to get the job done correctly the first time.

The secondary carburetors on the 140 hp engine often see little use. Quite often only the primaries are in operation for perhaps 90% or more of engine operation (depending on the driver behavior). The lack of use of the secondaries can cause problems because of their inactivity. The throttle mechanism, as mentioned earlier, can get gummed up with lack of use, and may stick partially open, since only the spring in the accelerator pump provides any spring tension to close the throttle in the secondaries. The fuel in the float bowl can also become stale and can even evaporate to the point where it forms deposits in the fuel passageways inside the carburetor that can hinder proper operation. If the throttle sticks partially open and does not close completely this amounts to a vacuum leak that can cause a lean mixture by permitting too much air into the intake manifold to thin the fuel air mixture that is provided by the primary carburetors. If you're aware of these potential problems you can adjust your driving habits to engage the secondary carburetors more frequently to try to keep them in proper operation and avoid problems that can occur from the secondaries being idle and unused for long periods. You can also use carburetor cleaning spray to remove deposits from around the secondary throttle butterfly in each carburetor as a part of your tuneup procedure. This can help to ensure smooth operation of the secondary carburetor throttle butterflies.
Thank you for this. It is possible I may be over thinking. I just want to make sure I put all the proper parts in since problem solving later may be a Pain with all the changes I am making and the lack of experience I have with any motor. But I am also a perfectionist!

I have all new gaskets including the thick one on the base to sandwich. My float though was absorbing gas so I am buying a new one and waiting for that than close up.

Unfortunately I live in a city and the only way to get those secondaries open is to hit the freeway, which I will do.

Thanks to both and all for the detailed info that I will reference for years to come and I hope it's helpful to others.



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66corsaguy
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Re: Secondary carb internal components image

Post by 66corsaguy »

bbodie52 wrote:It sounds like you're making too big a thing of the secondary carburetors. The secondaries are essentially a subset of the primary carburetors. As it states on page 6M–8 of the 1965 Corvair Chassis Shop Manual, "The Rochester H carburetor is used as a secondary carburetor on the Corvair 10700 series (4×1 carburetors)… Has no choke, idle, power enrichment or low-speed circuits".

While it has no choke or idle circuits, it still has a float bowl and floats which require the replacement of the needle and seat assembly and adjustment of the float height and float drop (just like the primaries). Of course, all of the gaskets are changed out in the metal carburetor components should be soaked in carburetor cleaner solution and thoroughly rinsed and dried. The accelerator pump assembly is retained, since its mechanism and spring assembly is used to help put spring tension on the throttle butterfly to keep it closed. The lack of power enrichment and low-speed circuits does not change anything that would be swapped out from a rebuild kit. The fuel inlet gaskets and filter are the same as the primaries. Everything that is illustrated in figure 20 (Bowl Cover – Exploded View) is essentially identical between the secondaries and primaries, with the exception of the missing choke butterfly that is not a part of the secondary carburetors. Cleaning and inspection of the secondary carburetors is described in detail in the paragraphs following figure 20. Of the items shown in figure 21, I believe that items 11, 12 and 13 are the only things you will find in the rebuild kit that are replaced in the carburetor body. It is not necessary to remove item 14 (main metering jet) or the retaining screws (item 8) that hold the throttle butterfly valve in place. In fact, the main metering jet is a brass component that is often tight and difficult to unscrew, and might be damaged if you attempt to remove it. Carburetor parts dip cleaning fluid will still be able to enter the carburetor passages with the jet in place. Attempting to remove the throttle valve retaining screws from the carburetor body or the choke valve retaining screws from the bowl cover is usually not recommended as a part of the cleaning process. The threads on the screws are staked at the factory to prevent them from accidentally coming loose and potentially being sucked into the engine intake. To remove the screws it is necessary to grind off the threads at the end to remove the staked portion so that the screws can be removed. Once this is done, new screws need to be purchased to replace the old screws, and the threads must be staked as they were at the factory to ensure that the screws do not come loose because of engine vibration.

Not all carburetor rebuild kits are identical. The components that are included are usually made of rubber or gasket material, or have a tendency to wear. Just match them up and replace them after soaking the metal carburetor components in carburetor parts dip and rinsing and drying the carburetor components prior to reassembly.

In addition to the carburetor rebuild kits, you may wish to purchase four of the thick insulator spacers to replace the old ones. These spacers can become brittle and may be damaged when removed. Reusing damaged spacers could create a vacuum leak, and omitting them can cause the carburetors to transfer too much heat from the intake manifold, which can cause the gasoline to boil and vaporize within the carburetor body. In addition to the spacers, a carburetor base gasket should be installed above and below the spacer to sandwich the components in a way that will form a proper seal and eliminate the possibility of a vacuum leak. Replacing the carburetor inlet filter "stones" during the carburetor rebuild may also be advisable, and these are not included with most rebuild kits.

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The combination of the Rochester carburetor manual and the factory shop manual does a pretty good job of describing and illustrating the components of the Corvair Rochester carburetors. The first half of the Delco Rochester carburetor manual does a very good job of describing carburetor operation and the function of the various components that make up the Corvair carburetor. It is worthwhile taking the time to read through this manual so that you can gain a good understanding of the function of these carburetors — knowledge that can help you in the future with tuning and troubleshooting carburetors on the Corvair. The Rochester H and HV carburetors are not complicated or difficult to rebuild. But mistakes with improper or incomplete cleaning or improper assembly and adjustment can cause problems when driving the car that may require a second effort to get the carburetors right. It is better to take your time and read the material available to you to get the job done correctly the first time.

The secondary carburetors on the 140 hp engine often see little use. Quite often only the primaries are in operation for perhaps 90% or more of engine operation (depending on the driver behavior). The lack of use of the secondaries can cause problems because of their inactivity. The throttle mechanism, as mentioned earlier, can get gummed up with lack of use, and may stick partially open, since only the spring in the accelerator pump provides any spring tension to close the throttle in the secondaries. The fuel in the float bowl can also become stale and can even evaporate to the point where it forms deposits in the fuel passageways inside the carburetor that can hinder proper operation. If the throttle sticks partially open and does not close completely this amounts to a vacuum leak that can cause a lean mixture by permitting too much air into the intake manifold to thin the fuel air mixture that is provided by the primary carburetors. If you're aware of these potential problems you can adjust your driving habits to engage the secondary carburetors more frequently to try to keep them in proper operation and avoid problems that can occur from the secondaries being idle and unused for long periods. You can also use carburetor cleaning spray to remove deposits from around the secondary throttle butterfly in each carburetor as a part of your tuneup procedure. This can help to ensure smooth operation of the secondary carburetor throttle butterflies.
Thank you for this. It is possible I may be over thinking. I just want to make sure I put all the proper parts in since problem solving later may be a Pain with all the changes I am making and the lack of experience I have with any motor. But I am also a perfectionist!

I have all new gaskets including the thick one on the base to sandwich. My float though was absorbing gas so I am buying a new one and waiting for that than close up.

Unfortunately I live in a city and the only way to get those secondaries open is to hit the freeway, which I will do.

Thanks to both and all for the detailed info that I will reference for years to come and I hope it's helpful to others.



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