Hi,
I have a 1956 Chevy Bel air automatic with a 6 cylinder. It has a 1 barrel Rochester Carb.
When I start the car in the morning with a cold engine, the choke operates correctly and it fires right up.
When it warms up and I throttle it, it drops to a very steady 575 rpms.
My problem is after a drive. When I put it in park after a drive it idles a 1100 rpms instead of 575 rpms.
I bent the rod to try to adjust what I believe is the fast idle, but no luck. Is it time for a carb rebuild or am I missing something here?
Thanks for any help!
It could be many things and my first thought is binding is the pOWER gLIDE KICK-DOWN LINKAGE OR THE CARBURETOR LINKAGE
It is EASY TO SEE IF THE FAST IDLE CAM IS FREE AND DROPS DOWN AT HOT IDLE.
i DOUBT IF IT IS AN INTERNAL CARB. PROBLEM.
The fast idle will drop down at hot idle after I Rev the engine. All the linkages around the carb move freely.
It is only after a drive where the idle doesn't drop down. When I drive up the street at 25 mph and come to a stop sign, if I through it in neutral it idles right at 575 rpms. When I continue the drive up to 45-50 mph per hour and I put the car in neutral, it idles at 1100 rpms.
Does that shed light on anything?
I think you may be right with the power glide kick down linkage. I have never adjusted one so I need to read up on that.
I would lube the linkage pivots and swivels for both linkages with a no oil lube like WD40 first.
When it idles fast didyou try pulling the linkage back by hand at the carb.?
Yes, I did try pulling the linkage back by hand but after the car is driven at highway speeds, it doesn't want to drop down to idle. The linkages seem to all be moving freely.
Check the accelerator pedal and the tip of the rod that rides on the back of the pedal and the plastic insert on the back of the pedal.
Does the engine have a vacuum leak such as a bad wiper hose (eletric wipers?)
Chev Nut, what am I looking for here? Deterioration of the pedal or a missing plastic insert?
Everything looks good on the pedal.
I think the problem may be in the spring that pulls all the linkage back when you take your foot off the gas. It is the spring that is visible below the carb in front of the transmission that is attached to the linkage going to the carb. That spring looks to be original to the car.
I noticed that the spring is not being pulling the linkage all the way back toward the trans, and when I push the linkage back by hand, the rpms drop.
What is that spring is called?
Accelerator return spring. It has probably lost some tension due to old age You can take and cut oss about and inch and rebend the end.
I think that fixed it. Thanks.
You might try a little light oil before you take it apart. When I was driving my '40 as a work car, I would periodically have to oil between the two bell cranks. Mine seemed to gum up but a little light oil both cleaned and lubed enough that idle no longer hung up.