1971 Stalling when Idle
Thread Starter
Instructor
Joined: Apr 2011
Posts: 154
Likes: 0
From: Grand Haven Michigan
1971 Stalling when Idle
I have a 1971 Coupe with the base engine and an edelbrock carb. After driving for about 5-10 minutes when I come to a stop light or stop sign and have to sit the idle gets rough and eventually stalls out. I just had it in the shop to fix a few oil leaks and the guy adjusted the idle speed on the carburetor. It runs alot better when it is just started up, but it eventually starts to act up. Also when I got it there was a wire holding the choke open.
Is there anything i should look at or check?
Thank You,
Jay
Is there anything i should look at or check?
Thank You,
Jay
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
If you let it sit in the driveway and idle, can you recreate the problem? If so it would make it easier to track down.
Your idle in gear should be higher than 500 rpm, at least 600 I would say. If its dropping from 1000 to 500 rpm when you put it in gear its probably not running great even when its still cold either.
Some general tuning of timing & idle fuel mixture may be in order.
Based on what I see in your pictures, you might want to change the carb base gasket out to one of the 1/4" thick types.
The carb can get hot enough while running to start the fuel in the bowl boiling, which can lead to the types of problems you mention.
The thicker gasket helps to stop a lot of the heat transfer from the intake.
Your idle in gear should be higher than 500 rpm, at least 600 I would say. If its dropping from 1000 to 500 rpm when you put it in gear its probably not running great even when its still cold either.
Some general tuning of timing & idle fuel mixture may be in order.
Based on what I see in your pictures, you might want to change the carb base gasket out to one of the 1/4" thick types.
The carb can get hot enough while running to start the fuel in the bowl boiling, which can lead to the types of problems you mention.
The thicker gasket helps to stop a lot of the heat transfer from the intake.
Melting Slicks
Joined: Mar 2008
Posts: 2,023
Likes: 6
From: Austin Tx
Another thing to check are the connections at the coil. Loose or frayed connections will result in increased heat and resistance.
The cloth covered wire is the wire that connects to the starter, it is designed to provide additional power to the coil while starting. Check the connection at the starter, and make sure it is good. Also, try to make sure that this wire is away from the exhaust as much as possible.
If you have a volt meter, start the car, and check the number of volts on the +, and - side of the coil when first started, and check again later when the car is wanting to stall.
I had a problem where I had a frayed connection at the starter. It would run great at first, but as the engine warmed up, it would run progressively worse. It would start by wanting to stall at idle, and would eventually lead to where it would not run at all until it cooled down.
The cloth covered wire is the wire that connects to the starter, it is designed to provide additional power to the coil while starting. Check the connection at the starter, and make sure it is good. Also, try to make sure that this wire is away from the exhaust as much as possible.
If you have a volt meter, start the car, and check the number of volts on the +, and - side of the coil when first started, and check again later when the car is wanting to stall.
I had a problem where I had a frayed connection at the starter. It would run great at first, but as the engine warmed up, it would run progressively worse. It would start by wanting to stall at idle, and would eventually lead to where it would not run at all until it cooled down.
Racer
Joined: Feb 2010
Posts: 362
Likes: 10
From: nashville tn
Where's your PVC valve? Have you ck your eng vacum?
May want to consider changing the carb fuel inlet to a 90 deg so your air filter will not rub on it, also you cold try insulating and or relocating fuel line and filter to keep from heat soaking it as well, I used " fire hose" from a comercia
l hose and rubber supply co. You can see a little of it (orange) in the corners of the photo.
May want to consider changing the carb fuel inlet to a 90 deg so your air filter will not rub on it, also you cold try insulating and or relocating fuel line and filter to keep from heat soaking it as well, I used " fire hose" from a comercia
l hose and rubber supply co. You can see a little of it (orange) in the corners of the photo.
Thread Starter
Instructor
Joined: Apr 2011
Posts: 154
Likes: 0
From: Grand Haven Michigan
I found that my electric choke is powered off of the coil that is connected to the distributor and sits at 9V.
I was tracking down the fuse box and... was rather shocked at what i saw, even though I shouldn't have been.
My maintenance and service books are due to arrive next week, so I am not sure what Fuse is for what, can anyone help me on this? As in what fuse is what.
Thanks,
Jason
I was tracking down the fuse box and... was rather shocked at what i saw, even though I shouldn't have been.
My maintenance and service books are due to arrive next week, so I am not sure what Fuse is for what, can anyone help me on this? As in what fuse is what.
Thanks,
Jason
Thread Starter
Instructor
Joined: Apr 2011
Posts: 154
Likes: 0
From: Grand Haven Michigan
I have been trying to track down an idea on what is going on with this problem. I know right now based on what i found on the fuse box I have some wiring to look into. But with the carb, when everything is warmed up, what is in play? Is the electric choke still in play? Is it just the idle/fast idle screw settings? Also, what effect does having a fluctuating voltage of 9v-12v on the electric choke effect?
Thank you!
Thank you!
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Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Couple of things to check.
Vacuum leak, with the engine warmed up, cover the carb intake with your hand to block the air flow. If the engine idle starts to pick up instead of dieing off, it is lean.
Timing. Put a timing light on and watch while the engine is idling and see if it changes when dropped into gear.
The electric choke should not be hooked to the coil. Hook it up to the ign or acc tap in the fuse box.
Vacuum leak, with the engine warmed up, cover the carb intake with your hand to block the air flow. If the engine idle starts to pick up instead of dieing off, it is lean.
Timing. Put a timing light on and watch while the engine is idling and see if it changes when dropped into gear.
The electric choke should not be hooked to the coil. Hook it up to the ign or acc tap in the fuse box.
Last edited by '75; Jul 9, 2011 at 10:40 PM.