First carb rebuild...hard earned success
- Thread starter FJ Noob
- Start date
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Great work. I bet it cold starts with no issue now.
- Thread starter
- #103
I've been driving the truck on and off since the rebuild and learning about the peculiarities of the burping the 2F after coolant system work (totally different saga). The carb has been doing pretty good, but I've noticed something in the last couple of days...
After start up and giving it a little time then releasing the choke, it settles right down to around 650-700 rpm at idle. When I drive for a bit and come to a light and idle, it only comes down to around 1000 and today was only getting to down to about 1100 rpm. It did this too while I was burping it the other night after giving a little gas to help get it to operating temp. I reached in an lightly pushed up under the a/c idle up screw, helping the throttle plate rotate back closed and it settled right down to 650 rpm.
It seems like my plate isn't always returning to a "closed enough" position. Is this actuated purely mechanically by the spring and lever set-up on the firewall side of the carb or is there something else that helps it "reset"?
After start up and giving it a little time then releasing the choke, it settles right down to around 650-700 rpm at idle. When I drive for a bit and come to a light and idle, it only comes down to around 1000 and today was only getting to down to about 1100 rpm. It did this too while I was burping it the other night after giving a little gas to help get it to operating temp. I reached in an lightly pushed up under the a/c idle up screw, helping the throttle plate rotate back closed and it settled right down to 650 rpm.
It seems like my plate isn't always returning to a "closed enough" position. Is this actuated purely mechanically by the spring and lever set-up on the firewall side of the carb or is there something else that helps it "reset"?
Did you do this?
- Thread starter
- #105
Yep...cleaned it all up when I fixed the insulator. I should just stop asking questions before I look through your threads. Jumping from linked thread to linked thread, I've got some other areas to look at. Tomorrow I'm going to take a closer look along everything from from pedal to carb.
I want to finish reading about your vac advance rebuild first though!
Check the AC idle up screw for proper clearance. If it is touching when the AC compressor is off it wont allow the butterfly to close all the way causing a higher idle. It is located on the front (radiator side) of the carb. When the AC idle up is activated, it opens the butterfly to increase the idle so the AC compressor wont kill the engine. That screw should not be touching when the AC compressor is disengaged. Once AC compressor is engaged you use that screw to set the idle up RPM. I do believe it is between 1000-1200 RPM.
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Awe thanks but I can’t take credit, I didn’t rebuild it, I just pulled it apart.
- Thread starter
- #108
Thought about that the other day when I was looking at how the linkages work. I backed the screw out so there’s a 1/8 inch gap to make sure it wasn’t the culprit. Just to make sure, I also pulled the vacuum hose off the attached diaphragm while running to just make sure it wasn’t stuck for some reason. When I had the carb apart, everything checked out per the FSM and comparing to my other carb. The only change has been installing it in the truck and reattaching the linkages. I’m tempted to focus on everything from the pedal to accelerate pump because it acts normal when I push the choke in...before touching the pedal. Although I have learned thus far to not count out seemingly unrelated items when troubleshooting on these trucks.
- Thread starter
- #109
I was pretty into it until I hit the post about finding a secret stash out in TX...
There are a couple of other things to check:
The choke high idle screw. Make sure it is completely off when the choke is pushed in.
The secondary plate is completely closed.
The primary linkage is allowing the plate to close completely.
The choke high idle screw. Make sure it is completely off when the choke is pushed in.
The secondary plate is completely closed.
The primary linkage is allowing the plate to close completely.
- Thread starter
- #111
I can see daylight under the high idle screw and the secondary plate is closed. I think it has something to do with part of the linkages. Two things I noted today...
1) I can LIGHTLY press the peddle with my index finger and get increase in RPM just out of the travel "play"...like a 1/16 of an inch or so
2) It doesn't seem to stay higher if I work the linkage at the carb by hand and let it "snap" back into position....only if I simulate slowly and evenly coming off the gas like when rolling up to a light.
I'll go back to the FSM and run through the pedal & linkage adjustment procedures.
- Thread starter
- #112
@2mountainfish ... What year is your truck and/or is that the original carb? Neither of my 2 stock carbs have that spring on the front like in your picture. Not as in they are missing, there is not any attachment points like you have. Interesting....
That actually is a photo from another thread I read, not mine. It might actually be a Aussie carb, as the poster lives in Australia.
