[FC] powerglide question/Carb adjustments

[Ken Hand]

I have had this very thing happen to me on my own and customer cars. The problem should mostly lie in carb adjustment. The first thing to check is the idle mixture, adjust the idle mixture out until you get a drop in RPM then adjust in past the point of good running and you get another drop in RPM. Adjust the mixture out until you get the best idle and add 1/4-1/2 turn additional out on the mixture screw. Do this to both carbs. Now go to the idle speed, on a free idle(neutral) you should be somewhere about 650-700 RPM. In gear you should be at 550-575 RPM. And, when you take it out of gear should give you the above mentioned free idle(neutral) RPM. The place to adjust the idle speed is in gear and the mixture in neutral. If the idle speed was way off then go back and adjust the mixture again and if needed the idle speed afterwards. 

I probably should have started with this but you should probably mechanically equalize the carbs. You will need to take the choke rods off the levers then take off the left carb link at the top and the throttle rod from the cross shaft, then back the idle speed screw all the way out. Feel where the idle speed screw just starts to open the throttle by putting your finger under the screw and on the shaft. Turn the screw in and then out until you get a feel for where it starts to open the throttle. Once you have that spot look at the screw head and turn it in another 1 1/2 turns. Do the same to the other carb. Now, pull up on the link to see if your link still lines up with the hole in the cross shaft. If it doesn't adjust it until till it does and reconnect. NOTE; I always put the return spring back on the cross shaft to simulate the state it will be in when in use, do this before the link adjustment. After this you really should put a Unisyn on the carbs for final balance adjustment but if you don't have one you CAN use the back of your fingers over the carb top and feel how much air is passing and if there is a great difference adjust the idle speed on a carb depending on the current idle speed. If you make a big change on one carb's idle speed screw, readjust the link on the left carb. Once you have the carbs balanced in this way whatever idle speed adjustment you do to one carb you do to the other if you need to change the speed. Remember to reconnect the throttle rod to the cross shaft and the choke rods to the levers.  IF you feel your carbs are balanced good enough you can skip this part.

Mixture and idle speed are the biggest part of stalling with an PG. Timing is next down the line, if you have the timing retarded this will contribute to the stalling.

I hope this isn't to much info.


Ken Hand
248-613-8586
www.corvairmechanic.com



-----Original Message-----
From: Wild8bill at aol.com
To: corvanatics at corvair.org
Sent: Mon, Mar 8, 2010 2:51 pm
Subject: [FC] powerglide question


When I shift into D or R, sometimes the motor dies, brakes on or not. Is  
his a symptom of something in the powerglide, or the motor? Everything works 
fine otherwise, and this happens less when warmed up.

Bill