• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR2/3/3A Idle

Share this page

F

frankfast

Jedi Trainee
Offline
After synchronizing the carbs (working the linkage at the motor) and adjusting the idle to 850 rpms when warm (previously adjusting mixture with plug checks), took it out for a ride. Came to a stop light and the idle very slowly comes down to 1100 rpms and no further. Is the linkage binding? Carb internals worn? Looking for a solution.
 
If they are SU carbs maybe the holes for the throttle shafts need bushings....too much annular space will increase the air coming in and the idle speed along with it.
 
It's possible the linkage is binding especially around the bellcrank area underneath the front car. Can you bring the idle back down if you hook your toe under the accelerator and pull it up?

Cheers
Tush
 
Frank,
I usually don't like to comment on something that I haven't tried. I have the same problem with my 56 TR3, won't idle below 1,500, but I can push the linkage under the hood back to an 800 idle. In a thread on BCF, I read that the universals on the linkage at front of the front carb tend to bind a bit and can cause the throttle shafts to leak (what Ken said) or just bind at the bellcrank and not let the throttle plates go back to idle (what Tush said). The recommended fix, that I have not tried, was to get 1/2 turn more compression on the two springs (just in front of each carb body) on the throttle shafts. I have not tried this yet, but looked at the springs and retainers today. I don't think I can see where the spring tabs will be held if you go 1/2 turn tighter. I am only suggesting that you look because it may be a week or two before I can try this remedy myself.
Good luck!
 
jfarris said:
Frank,
I usually don't like to comment on something that I haven't tried. I have the same problem with my 56 TR3, won't idle below 1,500, but I can push the linkage under the hood back to an 800 idle. In a thread on BCF, I read that the universals on the linkage at front of the front carb tend to bind a bit and can cause the throttle shafts to leak (what Ken said) or just bind at the bellcrank and not let the throttle plates go back to idle (what Tush said). The recommended fix, that I have not tried, was to get 1/2 turn more compression on the two springs (just in front of each carb body) on the throttle shafts. I have not tried this yet, but looked at the springs and retainers today. I don't think I can see where the spring tabs will be held if you go 1/2 turn tighter. I am only suggesting that you look because it may be a week or two before I can try this remedy myself.
Good luck!
Click to expand...

I've tried it and it worked on mine. One side of the spring locks into a brass insert tied to the side of the carb. The other is loosened/tightened with a 1/4" nut and bolt. This does, of course, assume there are no issues with the carb (binding or worn shafts) or linkage (belcranks and rods in good condition and geometry). I had new shafts and completely rebuilt linkages, and tightening the end spring brought the idle to rock solid setting every time...no more "blipping" or pulling it up with your toe.

Here is a pic...obviously a "before" pic, showing the shaft end spring.

KSsrWtR.jpg


You just loosen the tiny bolt, wind the spring a bit tighter, and re-tighten the bolt.
 
I thought about that when I was lubing the joints. It seems that the more pressure that you put on the linkage to return, the better it would work. I was a little intimidated to loosen the nut because I didn't know how the spring would uncoil. But I think that I'm going to try it. The revs do return to idle with a little pressure by hand on the linkage.
 
I tightened the springs and the motor returned immediately to a nice 800rpm working the linkage by hand at the engine compartment. But when I took it for a ride the idle would not go below 1000rpms at a stop. Since I'm working by myself, I can't see if the accelerator pedal moves when I'm working the linkage at the engine compartment. I'm assuming that it does so I'm still confused why it doesn't return to a proper idle when I'm driving the car.
 
Frank, time to start spraying some carb cleaner around the intake manifold and butterfly shafts. If the idle goes up you have found your problem.

Wayne
 
Just went through this exercise on my 1958 TR3A. I just finished resolving a few weeks earlier. Issue was that when driving the idle would remain high at a stop light. It was suggested that the trottle (sp?) shaft on the right carb could be worn due to the linkage pulling over time on the trottle linkage.

I had to agree with this assessment and did two things:

1) Sent the carb body to Apple Hydraulic in New York to have the carb body reamed and a new bushing and throttle shaft installed. I shipped from California on Monday and it arrived back on Friday. Check the website for instructions for shipping. Price was $85 plus shipping.

2) I also purchased a new throttle shaft linkage from a supplier based in Seattle. It was worn. Not sure if it was needed, but I am very happy with the results. I recall the price was about $100.

So the good news is that it can be fixed. I am extremely happy with how things turned out for me. Good luck.
 
SteveBones said:
Just went through this exercise on my 1958 TR3A. I just finished resolving a few weeks earlier. Issue was that when driving the idle would remain high at a stop light. It was suggested that the trottle (sp?) shaft on the right carb could be worn due to the linkage pulling over time on the trottle linkage.

I had to agree with this assessment and did two things:

1) Sent the carb body to Apple Hydraulic in New York to have the carb body reamed and a new bushing and throttle shaft installed. I shipped from California on Monday and it arrived back on Friday. Check the website for instructions for shipping. Price was $85 plus shipping.

2) I also purchased a new throttle shaft linkage from a supplier based in Seattle. It was worn. Not sure if it was needed, but I am very happy with the results. I recall the price was about $100.

So the good news is that it can be fixed. I am extremely happy with how things turned out for me. Good luck.
Click to expand...

Some background. I tried taking apart the trottle linkage and lubricate/ grease all connections. This did not help in my case. It was the worn throttle shaft causing the throttle butterfly to stick when returning to idle.
 
Back
Top