Need pics of 273 4 BBL choke

-
Greasyfingers

Greasyfingers

Well-Known Member
Joined
Jul 16, 2019
Messages
403
Reaction score
432
Location
Morgan Hill, CA
I've been fighting a stuck choke on my 66 273 4 bbl for quite sometime. Pretty much just wired it open, but now I want it to work properly. I've looked at pictures of NOS chokes online and the bend on the rod looks different than the one I have. Of course probably would look different mounted on an intake. Currently mine won't fully open.

Here's a picture of what I have. I would like to see if anyone has a picture of theirs, so I can compare. This will help me figure out if my rod is bent incorrectly or not.
IMG_20200812_172638708.jpg
IMG_20200812_172717865.jpg

Thanks,
Aaron
 
Ooooo I don't know if I have any photos or not. Let me look. I switched mine to electric when I put a Edelbrock on. I was having issues with my 100,000 mile original 4 speed carb. They wear out with on and off the throttle through 4 gears for 100,000 miles. Automatic carbs not so much. (1/4 to 1/2 throttle once and then it stays there)
 
Greasyfingers said:
I've been fighting a stuck choke on my 66 273 4 bbl for quite sometime. Pretty much just wired it open, but now I want it to work properly. I've looked at pictures of NOS chokes online and the bend on the rod looks different than the one I have. Of course probably would look different mounted on an intake. Currently mine won't fully open.

Here's a picture of what I have. I would like to see if anyone has a picture of theirs, so I can compare. This will help me figure out if my rod is bent incorrectly or not.View attachment 1715577152 View attachment 1715577153
Thanks,
Aaron
Click to expand...
It looks like it's closed. The butterfly should have slight tension (and not 80° outside). The choke pull off (vacuum diaphragm)
should pull the butterfly open 1/4-1/2" when the engine fires and the thermostat in the intake should continue to open the choke as the engine warms up. All the components need to work properly for the choke system to work as designed.
 
Picture is with motor cold and not running. The pull off works as it should. When motor is warmed up the choke stat doesn't pull the butterfly all the way open. Which won't allow the carb to come off of the fast idle.
 
Greasyfingers said:
Picture is with motor cold and not running. The pull off works as it should. When motor is warmed up the choke stat doesn't pull the butterfly all the way open. Which won't allow the carb to come off of the fast idle.
Click to expand...
It may need a new choke thermostat down in the intake. Also, the heat riser in the passenger exhaust manifold should be working properly and the passageway under the carb opening in the intake needs to be clear of carbon. All the pieces need to be good for the choke system to work properly.
 
After running to full operating temp, running the fast idle screw out to eliminate it from holding throttle open, this is as far as the butterfly will open.
 
Oops forgot picture.
IMG_20200812_183442553.jpg

Maybe a bad stat. Just won't pull it open. At the prices these parts are going for it may have to wait.
 
That's definitely a different angle than how mine is. I'm going to pull it off and check the operation of the spring. If spring seems to function correctly I'll try to bend the arm. Maybe the rod needs more of a bend to pull the butterfly open all the way.
 
You might need to remove it, and adjust the spring tension lighter by loosening the nut (as seen in CudaAl's post). Also, make sure the rod pulls the choke butterfly open completely when it's hot, You may have to bend the rod to get it right.

Mine's a bit mangled....but it works....

IMG_2050 (Small).JPG
 
Last edited:
The original only has two bends, the rod goes up, angles forward and towards the carb and then into the rod hole.


Alan
 
sometimes you can tighten the spring under the choke cover to adjust opening or closing.
 
Since I got it nice and hot I'll wait until tomorrow evening to take it a part. The different pics help a lot and the possibility of being able to adjust the spring tension may get me where I want it.
Thank you
 
Got the choke stat off tonight. to me this spring is on backwards or broken where the rod would be captured by it. As it is heated it functions, but doesn't actually pull on the rod. The rod just falls with it. If that is the way it is supposed to work than the rod is binding on the housing and needs to bent differently.
IMG_20200813_185637758.jpg
 
Check for a blocked exhaust cross-over passage on the intake manifold
 
Last edited:
Greasyfingers said:
Got the choke stat off tonight. to me this spring is on backwards or broken where the rod would be captured by it. As it is heated it functions, but doesn't actually pull on the rod. The rod just falls with it. If that is the way it is supposed to work than the rod is binding on the housing and needs to bent differently.View attachment 1715577733
Click to expand...
That's exactly the way mine looks too. In your pic, as the spring warms up, it'll turn counter-clockwise, and the weight of the rod, etc. will pull open the choke butterfly and fast idle cam. Make sure all of this is freed up and moving easily. You also may need to bend the rod to get the choke to open fully.

IMG_2387.JPG
 
Thank you for the comparison to mine. I'm definitely going to have to bend the rod to get it to work properly. If I set it up in my vice and heat the coil the rod binds on the disc. Now I know for sure which direction to go to make this operate properly.
 
Oh and the service manual was absolutely useless for information on this. Only said to set 2 notches on the rich side and nothing else.
 
Greasyfingers said:
Thank you for the comparison to mine. I'm definitely going to have to bend the rod to get it to work properly. If I set it up in my vice and heat the coil the rod binds on the disc. Now I know for sure which direction to go to make this operate properly.
Click to expand...
Can you remove the rod and enlarge the slot in the plate?
 
It's actually the angle that rod comes out of the base. It really should come up straight and than bend forward. Mine comes out at angle right away and when it warms up it can only drop a little before it's bound up.
I don't know how I over looked it for so long. I guess getting fixated on something blinded me from looking for the more obvious.:BangHead:
 
I may still have a extra choke here. The intake had 1 in it and the carb purchased later had 1 dangling from it. Installing the thickest available spacer under the carb is pretty common, due to todays fuel. That screws with the choke travel also.
 
You must log in or register to reply here.
-

Back
Top