Corvair Forum

6T5VAIR wrote: ↑Mon Mar 11, 2024 6:49 pm My secondaries are notched.

My carb specialist was surprised at this and thought perhaps four primary carbs had been adapted into the primary/secondary roles.

Can this be used without exchanging parts?

Some people do run four primaries on the 140HP engine. I would not do it, just me. You would have to identify WHAT model year the carburetors are on the engine. Only one decent source to do this ---- Bob Helt's book "How to Identify and Rebuild Corvair Rochester Carburetors".

The 1965 Rochester primary is more complex in function and in my opinion is NOT well suited to be a secondary. The point of using the 62-3 base for a secondary is it SIMPLE like a secondary. 64 and newer carburetors have refinements not needed or wanted on a secondary. The 62-3 base with the original secondary top allows you to adjust the idle mixture to eliminate the occasional idle mis-fire the 140HP is know for. Other than that it functions just like the basic secondary carburetor. If you don't have a secondary top you can modify a primary to work as one. I like to keep the 65-69 secondary top to use the later (smaller) floats that are more stable vs the earlier larger floats.

Bob's book is good at explaining the features. Keep in mind the Corvair carburetor had at least one design change EVERY model year.

The 1965 Rochester primary is more complex in function and in my opinion is NOT well suited to be a secondary. The point of using the 62-3 base for a secondary is it SIMPLE like a secondary. 64 and newer carburetors have refinements not needed or wanted on a secondary. The 62-3 base with the original secondary top allows you to adjust the idle mixture to eliminate the occasional idle mis-fire the 140HP is know for. Other than that it functions just like the basic secondary carburetor. If you don't have a secondary top you can modify a primary to work as one. I like to keep the 65-69 secondary top to use the later (smaller) floats that are more stable vs the earlier larger float

The car is going to the carb guru on Wednesday. Does the fact that I have notched secondary throttle plates mean this is going to be difficult to tame? Assuming for the moment these started out as four 1965 primaries, what mods should be done on the secondaries? Or is there another simpler path I should look at?