<VV> A/C car idle question

[William Hubbell]

Also, the most likely explanation for your customer’s issues is that his fast idle solenoid is either disconnected, failed or improperly adjusted, such that it fails to advance the throttle when the AC compressor runs.  Probably as a result of this, somebody has cranked up the idle speed on the carburetors in an attempt to keep the car from stalling and that is contributing to the poor mileage. 

Bill

On Apr 21, 2022, at 8:16 AM, William Hubbell <whubbell at umich.edu> wrote:


Grant,

Yes, a vacuum/electric idle advance unit is used on all 1962-mid’65 Corvairs with AC and they all get the vacuum from the choke pull off line as you described.   The purpose of the unit is to increase the idle speed when the compressor is running to prevent stalling the engine, due to the increased load of the compressor.

1961 had a smaller (A5) compressor and did not use a fast idle solenoid.

1962-65 units were mounted on the right condenser support and acted on the throttle cross-shaft by means of an attached finger (‘62-‘63) or fork (‘64-‘65). 1962-3 used a “pusher” unit, whereas 1964 through mid-1965 used a “puller” unit.  In mid-1965 they switched to an all electric unit, mounted in the same location.  1966 moved the solenoid to the left side and was attached to the top shroud (turkey roaster) by a single arm.  1967 added a second arm to better support the heavy all-electric solenoid. 

The mid-1965 all-electric solenoid was the replacement unit for all earlier models once it was introduced. 

The carburetors are identical to non-AC cars in every respect other than the addiction of the “T” fitting in the vacuum advance hose for the vacuum driven units. 

I have detailed photos on the Stock Corvair Web site here:

 http://stock.corvair.org/2014/08/corvair-ac-idle-speed-control-assemblies/

Also on Corvair Center Forum:

http://corvaircenter.com/phorum/read.php?1,1118052,page=7

Or, if you are on Facebook, here:

https://m.facebook.com/media/set/?vanity=StockCorvairGroup&set=a.168036950053874

And here is a photo of the “T” fitting - NOS!!




Bill

On Apr 20, 2022, at 9:39 PM, Grant via VirtualVairs <virtualvairs at corvair.org> wrote:

I am rebuilding the carbs on a 1964 PG sedan with air conditioning. The owner is also complaining about high idle and low gas mileage (8-10 mpg). It has a idle speed-up solenoid that it is plumbed to a T-fitting in the line from the base of the carb to the choke pull off. Is that correct? If the idle is turned down, it will shut off with the A/C on when coming to a stop. The solenoid is from a 1965 car if that matters. I only want to do this once since the carbs are a bit hard to get to.
 
Thanks
Grant
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