Pontiac High idle question

[daleone3]

1976 Pontiac Formula, 400 4spd. 9000 original miles so have been working thru a range of repairs over the past year due to the lack of use. The carb has been rebuilt and it runs very well but having issue with high idle and choke not kicking down. Fuel system is new. Rather than hucking parts at it, thought I would ask some of the great tech folks here.
Engine is original and never been out, fuel system is new and no obvious issues under the hood, have check vacuum etc.....
In looking at some of the resources, could it be an Idle Solenoid or a Choke Pull Off assembly? Idle sits around 1100 RPM and will not kick down.
Much of what has been replaced is due to age so any thoughts on what I might look at first very much appreciated.
Thank you!
Scott

[Big Block Bill]

Originally Posted by daleone3

1976 Pontiac Formula, 400 4spd. 9000 original miles so have been working thru a range of repairs over the past year due to the lack of use. The carb has been rebuilt and it runs very well but having issue with high idle and choke not kicking down. Fuel system is new. Rather than hucking parts at it, thought I would ask some of the great tech folks here.
Engine is original and never been out, fuel system is new and no obvious issues under the hood, have check vacuum etc.....
In looking at some of the resources, could it be an Idle Solenoid or a Choke Pull Off assembly? Idle sits around 1100 RPM and will not kick down.
Much of what has been replaced is due to age so any thoughts on what I might look at first very much appreciated.
Thank you!
Scott

Scott,
First thing to check is the choke blade all the way open (straight up and down) when it is totally warmed up?
If not, the choke thermostat is set to tight or something is binding. If so, the fast idle cam on the passenger side is either sticking or miss adjusted. A good starting point is when the car is totally warmed up to engine temperature and blowing hot air out of the heater, the choke blade should be straight up and down, set the high speed idle cam at it's highest point and adjust the rpm to 1800 rpm. You can look up all the specs of your carburetor by the carb number on a google search. Hope this helps.

Bill

[WILMASBOYL78]

Bill's instructions are a great start...always cover the basics before getting too far down the road.

If you still have questions...I suggest reaching out to Eric Jackson [Vintage Musclecar Parts]. He is the best in the business on carbs for GM muscle cars.

-wilma

[LT1vette]

Originally Posted by big block bill

scott,
first thing to check is the choke blade all the way open (straight up and down) when it is totally warmed up?
If not, the choke thermostat is set to tight or something is binding. If so, the fast idle cam on the passenger side is either sticking or miss adjusted. A good starting point is when the car is totally warmed up to engine temperature and blowing hot air out of the heater, the choke blade should be straight up and down, set the high speed idle cam at it's highest point and adjust the rpm to 1800 rpm. You can look up all the specs of your carburetor by the carb number on a google search. Hope this helps.

Bill

1800 rpm.....???

[daleone3]

Originally Posted by Big Block Bill

Scott,
First thing to check is the choke blade all the way open (straight up and down) when it is totally warmed up?
If not, the choke thermostat is set to tight or something is binding. If so, the fast idle cam on the passenger side is either sticking or miss adjusted. A good starting point is when the car is totally warmed up to engine temperature and blowing hot air out of the heater, the choke blade should be straight up and down, set the high speed idle cam at it's highest point and adjust the rpm to 1800 rpm. You can look up all the specs of your carburetor by the carb number on a google search. Hope this helps.

Bill

Thank you Bill, really appreciate the insight, will follow your lead and share where I end up, appreciate it!!

[Big Block Bill]

Originally Posted by LT1vette

1800 rpm.....???

Yes 1800 rpm is the most common setting on a warmed up, choke off, fast idle cam setting on the highest step. I went to a GM Class back in 1978 on drive ability and that's what i learned. It also had me buy books (2 - 10 inches thick) covering everything carbureted in the GM line from 1938 to 1987?. I have since sent them all to Eric at Vintage Muscle Car for his collection, he is the person who deserves to have this history.

Bill