ahhhoo wrote: » Mon Apr 29, 2024 8:51 am
1965 110 auto.
I will look into these. Thank you. I turned the idle screws back to normal this morning. Car started right up and idled nice til it warmed up. I just let the car run. As the car was warming up (a few minutes in), it was getting rougher and rougher and idle was getting lower and lower til it stalled. I am going to look at the choke too.
ahhhoo wrote: » Mon Apr 29, 2024 4:12 pm
Thanks brad for all your info. Lots to go through! Yes Massachusetts is beautiful and its funny you know where Belchertown is. I am sure most Massachusetts residence don't know where we are. I hope one day I can say that I loved driving around Rt 2 and the Berkshires in our Corvair. Feeling overwhelmed now.
The vacuum lines look good and snug. The carbs are getting jets of fuel into the chamber.
I did notice that the two butterfly valves were not lined up. One was fully open and the other, maybe a 3/4 or 1/2 open. The carbs were rebuilt.
Everything points to incorrectly adjusted and synchronized idle speed and mixture screw settings. Your description of a satisfactory idle speed until the engine warms up indicates that the FAST IDLE CAM on each carburetor associated with the choke systems is helping to keep the engine idling UNTIL GRADUALLY INCREASING ENGINE HEAT OPENS THE CHOKE MECHANISM AND DISENGAGES THE FAST IDLE CAMS.
Your second quote seems to indicate that you are looking at the choke butterfly valves at the top of each carburetor intake. There are two more butterfly valves at the bottom of each carburetor throat. THESE ARE THE THROTTLE BUTTERFLY VALVES. The individual carburetor choke butterfly valves may open at a slightly different rate, due to variations in engine temperatures as each cylinder head warms up. Both sides should be fully opened when the engine is at normal operating temperatures. The two
throttle butterfly valves at the bottom of each carburetor body will normally be very close to being mechanically equally synchronized from one carburetor to the other carburetor. Any slight variation is usually "dialed in" when fine tuning carburetor synchronization using a UNISYN airflow meter to measure actual airflow through each carburetor. Minor differences are corrected with small adjustments to each carburetor idle speed screw until equal airflow is achieved on each side, and the desired engine idle RPM is achieved. This is something of a "balancing act", working to achieve equal airflow through both carburetors and an acceptable idle speed with the engine.
i would recommend going through the idle synchronization procedure described in the shop manual.
1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE TUNE-UP, Page 6-5. This includes disconnecting the throttle linkage from each carburetor. Ensure that the choke mechanism and associated fast idle cams are disengaged and not affecting the idle speed settings. The you back out the idle speed screws so they are not contacting the throttles. A strip of paper is utilized to help you detect when the bottom of each idle speed screw is just in contact with each carburetor throttle. (Steps 3 - 7). When the strip of paper indicates that each screw is just in contact with the throttle linkage, each screw is adjusted in (clockwise) an additional 1½ turns. THIS WILL GIVE YOU AN INITIAL IDLE SPEED OF 500-600 RPM when the engine is at normal operating temperature had the chokes — INCLUDING THE FAST IDLE CAMS — are fully disengaged.
NOTE THAT STEP 11 HAS YOU ADJUST EACH IDLE MIXTURE SCREW IN UNTIL IT LIGHTLY BOTTOMS OUT, AND THEN YOU BACK IT OFF COUNTERCLOCKWISE 1½ TURNS. This is an initial preset for the amount of gasoline that is mixed with air at engine idle speed.
The attached
DELCO ROCHESTER - Models H, HV Carburetor Service Manual is also an excellent guide and provides more-detailed descriptions on the operation and component function of the carburetor subsystems and choke systems.
![chevy :chevy:](./images/smilies/chevybowtie.gif)