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78 Dodge d150 carburetor adjustment questions

Also there is a extra short screw with a spring on the linkage but I don't know that that there is for either. The truck started right up which was nice and the idle seem steady and not changing with the temp as it goes up. the only issue I have is that the idle is a bit too high and i can't seem to make it any lower. the screws for the idle and adjustment isn't even hitting the shaft at all. It is almost like the cable for the pedal may be allowing it to drop some. I can put a bit of pressure down on the arm and the idle will go down but I don't really want to do that until i can figure out what is going on.
 
I didn't get a picture of the extra screw in there but it's not hitting anything at all. I installed the carb and let it run for 25 minutes as i was trying looking around trying to see what may keep it for adjusting down for the idle. I didn't even adjust the fuel or air mixture screws as it just started right up.
 
Rude Robert said:
.......I can put a bit of pressure down on the arm and the idle will go down but I don't really want to do that until i can figure out what is going on........
Click to expand...
Are you thinking the cable is too short now and holding the throttle open?
 
I don't really know. I watched the choke open from being closed. When I tried to bring down the idle by hand since the Idle screw is not even touching the cam. I noticed that the throttle cable is firmly set so I was assuming if it were not attacked i could bring down the idle if that makes any sense.
 
It should be daylight soon and I am going to go back out there and probably pull that one out as i have never had that issue before and the carb doesn't totally look like my old one. I called a freight last night and he is thinking that the other arm may have been for a cruise control possibly? I may just take it back and have them order another one and put the old one back on, until i get the next one in.
 
Rude Robert said:
.........I noticed that the throttle cable is firmly set so I was assuming if it were not attacked i could bring down the idle if that makes any sense............
Click to expand...

If the cable is too tight, it surely can prevent the throttle plates from closing.
Pull of the cable.
Hold the throttle against the stop screw.
The cable should slide on the pin with no effort.

If too short, adjust the cable at the adjustment.


For reference.......

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okay thank you for that information. I saw that but I have never had to do that and I was thinking about it too. So I have owned the truck for like 28 years and I have changed the carburetor a few times but when I moved to Texas and I had to replace the carburetor. It was leaking fuel from most of the gaskets, it was time and been years since the last time that I changed it, plus there was snow on the ground and cold. I must have done a boneheaded move and when I replaced that carburetor back in 2022, I missed the additional vacuum line in the back that was added. I didn't have lights in the garage at that time and being so cold, I assumed it was the same as the one that was on there for years, but it wasn't. I didn't see it either until this morning. Last night when I put the new carburetor on and it started right up, except the idle being too high and the additional stuff that was on this carburetor, that wasn't on the one that I just removed. When I went outside this morning to work on the truck it was raining and it was a bit of surprise as even the news didn't see it coming. I had plans to do what my friend had suggested and put my hand over the mouth of the carb to see if it would stall out and it did. Okay so there is no vacuum leaks, so I am thinking that the carburetor must really be for another truck set up. I went to the store and then to the auto parts store to see if I can get another carb ordered and it wasn't an issue but the eta was for 1300. Went home and it was still raining so I was looking at the older carb that I just removed from the truck and noticed the back vacuum port wasn't plugged. Oh great don't tell me all of this time there was a vacuum leak. It was lightly raining and I remove the new carb since i was going to have the other new carb come in around 1pm. Plugged the old carb, as I know that there was nothing wrong with the idle as it could be lowered so it wasn't so high, installed it and it started right up. It is 1130, I put the new carb that had all those extra stuff on it, put it back in the box and asked if i can hold off on the order for now to recheck this carburetor. No problem he said and the $240 was put back into my account. After the wife went to sleep I drove the truck for about 20 minutes and it ran for the most part great. I didn't have any idle increase as I did before, I just need to adjust the air mixture screws a bit as to fine tune it but it's running. Thanks for the help guys.
 
If you were close by this is about when I just grab the tools and just start doing, sometimes I can do quicker and easier than trying to explain.
I'm about to do a carb swap in a 318 myself...
But I have to go a little deeper as I'm going from a 2bbl to a 4 bbl on my 78 fury
 
volaredon said:
If you were close by this is about when I just grab the tools and just start doing, sometimes I can do quicker and easier than trying to explain.
I'm about to do a carb swap in a 318 myself...
But I have to go a little deeper as I'm going from a 2bbl to a 4 bbl on my 78 fury
Click to expand...
I hope you have found the correct intake instead of wishful thinking.
 
Oh yeah. Got a "regular" performer, not an air gap or an rpm. Plenty for how this car gets used.
Debating between one of my TQs vs one of my AFB'S. Leaning towards the TQ
 
Can you send pictures of your work, when you get a chance and maybe a parts list. I really don't want too much power, i just would think that it would be easier to look for a 4 barrel carb, but not really sure on that. And since you are talking about that. My dodge only has 3 mounts two for the engine and one for the trans. I always have to replace the motor mounts every few years at they start to crack. When i do this, I change out the trans mount too. What i come across is that the trans mount seems to be shifted to the right a bit. I know its suppose to give a bit but and always off alignment and and need to move the trans to the left. I don't think those mounts especially for the engine are strong enough? Has anyone else experienced this?
 
What are you using for mounts? You know they make different types. I get about 10 years out of a set. NAPA truck mounts.
 
I just order what ever comes up from the Auto parts store. Sorry I haven't responded it has been a busy last 3 weeks with the grandkids, had some fun with them for sure. I order what ever comes up in their system for the motor mounts and transmission mounts. The engine mounts always see too small, if i remember its like maybe 2.5 inches wide and maybe 4 inches long. Before I had the engine rebuilt the first time long time ago was cheaply done but it worked okay, the truck leaked a lot of oil so I was assuming that the oil was eating up the rubber. Then after the first rebuild it didn't leak like that anymore but the engine mounts still needed changing every few years.
 
It sounds like the choke adjustment might be part of the problem, but there could be other issues too. Here are a few things to check:

Choke Adjustment: Make sure the choke plate is adjusted correctly. It should open up as the engine warms up. If it stays closed, it could cause starting problems and affect idle.

Idle Speed: Check the idle speed setting. It might need adjustment to stabilize the idle.

Vacuum Leaks: Look for any vacuum leaks around the carburetor and intake manifold. Leaks can cause idle issues.

Throttle Linkage: Ensure the throttle linkage is adjusted properly and not sticking.

Choke Thermostat: If the new choke thermostat is different from the old one, it might need adjustments to match your carburetor.

Addressing these areas should help with the idle and starting problems.
 
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