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4Ac - Trying For Correct Idle

Featured Replies

Hi all,

 

Just did a transplant and put a 4ac into my 70. It runs great only problem is it's idling way too high. It starts up nicely and then slowly the revs get higher and higher, when you step on the throttle it will raise the revs and then they will not return the revs just keep getting higher.

 

BTW I don't know anything about carby's.

 

Also another interesting thing is that I converted the 4ac from auto to manual and so it had like an auto choke linkage, when I move the auto choke mechanism thing it seems to make a diffeence in how the

throttle butterfly thing opens and closes, when I don't touch it the buttlerfly doesnt fully return and the butterfly stays open a bit, when I put a bit of tension on it the butterfly fully closes - I think this could be at least one of the problems, I assume with carby's when there at idle the butterfly should be fully closed.

 

throttle.jpg

 

Has anyone else used a auto to manual 4ac and had same problems? or any suggestions?

 

Thanks

The auto choke opening mechanism can probably be rotated/adjusted to put more spring pressure on the butterfly and allow it to close properly.

 

I don't know which method the 4A uses to control it, but they're usually either electrical or or mechanical in operation, and they are adjustable.

  • Author

does some one have a picture or is willing to take a picture of how this is on their manual 4ac.

The spring that sits behind one of the mechanisms in the photo is pretty loose so I'm not sure

whether it has been taken off before and maybe not put back on properly.

 

Or if anyone lives on the southcoast of nsw and wants to give me a hand getting the 4ac idling I can provide $$

I have a 2AC manual transmission, hope these pics help. First two are from the front, the third is from the firewall side.

 

post-5437-0-60185900-1352517716_thumb.jpg

 

post-5437-0-41485800-1352517843_thumb.jpg

 

post-5437-0-65201000-1352517877_thumb.jpg

  • Author

I have a 2AC manual transmission, hope these pics help. First two are from the front, the third is from the firewall side.

 

post-5437-0-60185900-1352517716_thumb.jpg

 

post-5437-0-41485800-1352517843_thumb.jpg

 

post-5437-0-65201000-1352517877_thumb.jpg

 

awesome, thanks very much!!, that second one seems to show the spring I'm interested in. I'll see how I go.

  • Author

It"S FIXED!!!!!!!, you would not believe what the problem was, I was trying to hard. I was looking at that spring thing thinking it was like

a return spring (which it probably is) so I was focusing so much on that I didnt even notice the butterfly linkage thing had become mis-aligned

and the split pin was half holding it on, about 5 seconds with a set of pliers and it was fixed

 

Thanks fellas

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