I will bump this thread because I have the same question. I am converting from a Holley to stock on my 60. Need to know what to do with the four ports at the base of the carb and the three on the top of the carb. I have seen the diagrams but they are hard to decipher. Also plan to use the stock air cleaner assembly and there are several orifices there. Please help. My truck was already desmogged when I got it otherwise I would have kept it smogged. Thanks
There's nothing different between somgged and desmogged carburetor only except some vacuum ports for emission control.
Mine is 3F motor with fully desmogged carb. from factory.
I disassembled, compared with my carb. and tested Japan version of smogged carb and found there's nothing different.
The only difference is smogged carb has vacuum port and desmogged carb has already plugged port.
If you plug vacuum ports, you can use smogged carb with your desmogged truck.
Please get emission control FSM. your can get every answer what you want.
They are go to HAI valve(Hot Air Intake), distributer HAC port(High altitude compensation), distributer vacuum advancer port, EGR valve,...etc.
I can't memorize everything but FSM can do that.
I would like to see pics of the ports that have been pluged on the carb. and any other parts that can be removed after headers installed. I just installed headers and it seems to be running fine with the stock carb, but I think it could be better.
The emissions control manual has some cryptic diagrams of the vacuum ports on the right lower side of the stock carb. Of the 3 lower ports, the one toward the rear is the one for the "Advancer Port" which is for the distributor (page 3-13). The lower one that is to the front is for the EGR (assumably removed..so plug) (page 3-13). The lower middle one goe to the HAC (HIgh Altitude Compensation) system (page 3-31). The one for the Fuel Cut Port is the upper one that is toward the rear (page 3-44). I think that I am reading this right.
Heart - I appreciate you checking that out. If one lives in Indiana (low altitude), does that mean the HAC could be safely capped? If I wanted to connect that one, where does it show it ends up? On the left side of the carb, there are three diaphrams with ports....two on the right and one on the left. The top right port is connected by way of a green switch to the middle port on the top front of the carb. I assume the other two (lower right and left diaphrams) are connected to manifold vacuum. Is that correct? Also on the left side is a bigger port between the right and left diaphrams. Where does that connect for a smogged system? Back to the top front ports. I assume the outer ones should be capped. Correct? I will try to post pics tomorrow when I get my camera back. Thanks.
When I went out to check my carb/vacuum lines, I developed some uncertainty about my set-up, so I am not making any guarantees that it is right. My big question is why I have the line from my bimetallic vacuum switching valve 1 (BVSV-1) going to the EGR-R port on the carb. However, the vehicle is getting about 15 mpg and runs great. Jim C. did the carb and distributor for me when I did the engine rebuild and de-smog. I live at 5200 feet elevation and did away with the HAC. Maybe you would need one going from low to high in Indiana. Jim re-jetted the carb for high altitude for me and I do not plan of taking my rig to sea level.
Having said that: Looking at the top of the carburetor while standing in front of the vehicle. The diagphragm at 2 o'clock is the choke breaker and it has a small line that goes to a vacuum port at 6 o'clock..I kept this. There is a small port on the top of the carb at 5 o'clock that is plugged. There is a diaphragm at 5 o'clock that helps kick up the idle if you have air conditioning. I do, so I kept it and sent the small vacuum line over to the left fender to a vacuum switch. There is a small vacuum port on at 7 o'clock on the top of the carb that I plugged. On the air cleaner there are 3 little ports in a row on the upper tier. I plugged 2 and used one to go the vacuum control valve for the EVAP. The two large openings, one on the upper tier and one on the lower tier, are plugged with some perfectly fitting plugs that Jim C. sold me ($1 each). I kept the HIC (hot idle compensation) valve and the HAI (hot air intake) diaphragm as is.
Thanks Heart. This is the kind of info I was needing so I hope it helps the guy who started this thread. Your description raises some other questions.
1. There is a diapgram with a port below the carb break diaphram. Where does that one go?
2. You said the AC idle up goes to a switch on the L. fender. I have one there that is elect. connected. Coming off the switch, where does the other vacuum line connect to...a vacuum source?
3. I thought the Idle cut port on the passenger side of the carb went to the electronic switch on the L. Fender. Since that is for the AC idle up, where does the idle cut port from the carb go to? I figure it needs to go to a switch too since it is also activated electronically. Any pictures would be very helpful.
4. So the large port at the base of the 5 oclock port on top is plugged. Does the lower large one (also plugged) come out of the carb insulator?
5. On the air cleaner, what does one do about the Hot idle compens. valve and Hot air intake diaphram if you have a header?
6. I also need to see what I need to get to properly hook up the Accel. cable. Hooked up to a Holley right now. The end of my Acc. cable has a 3-4 inch shaft that ends in a flat rounded spade with a hole in it. Does this sound stock? I notice on the carb that something needs to hook up to the little ball. Help with how that works would be very helpful.
very helpful thread. Comments or pictures from others would be most helpful.
Your question #1 is about the choke opener diaphragm. Mine was removed by Jim C. in the carb rebuild/de-smog set up. When I removed the carb for shipping, the small vacuum went from the choke opener to a tube on the "spagetti junction" of metal tubes. The one it went to was one by itself that sticks up right behind the 12 ports that point toward the left fender. In the metal tube, it goes toward the passenger side and "T"s. One branch of the "T" goes to one of the 3 little ports on the top tier of the aircleaner. The other branch goes to the outboard port of the bimetallic VSV #2 (pink) on the thermostat housing..
Your question #2. The AC idle up diaphragm tube goes to the switch that does have an electrical connection. The other vacuum line on that switch goes to the main vacuum source for the brake booster on the rear half of the intake manifold (there is a little outlet next to the big outlet)
Your question #3. The fuel cut vacuum hose comes from the lower passenger side of the carb to a vacuum switch on the left fender. Mine does not have a second hose. It appears that when the vacuum in the carb drops (you take your foot off the accellerator) it flips the electrical switch and sends a signal to the fuel cut solenoid to shut off the gas.
Question #4. I don't think I said plug the large port on the carb. There are two large ports on the air cleaner that I plugged. The large port on the top of the carb horn at 5 o'clock I think is a gasoline overflow pipe that drains gas back to the gas tank. You would want to keep that I think. You also asked about a large port coming out of the carb insulator. On my rig, that is going to the vacuum control valve for the EVAP on the firewall. It goes into the end of the switch. I kept that. Questions #5 and 6 I don't have a clue.
Note: I am a newby and some of this may be wrong. I apologize, but I don't have a camera. Please correct any misinformation.