What is the url for that?

 

Looks OK. Ya never know... Here it is though


https://rover.ebay.com/rover/0/0/0?m...2F392012490935

 

On order, thank you !

 

 

Another thing to try is to artificially enrich the mixture on that side of the carb/manifold. Hopefully there is a vacuum port on that side of the manifold that you can use to inject some propane gas into the engine. I am guessing you will notice things pickup and smooth out as those cylinders start to see some fuel. Propane is safe to use, in fact back in the early emission days it was used to sit the idle circuits. Normal if I recall right you looked for a few rpm increase and there would be a spec in the book while feeding propane gas to the engine. When you had that right then the carb was sit lean enough to pass emission test. Not saying they ran great just past the test. As I am typing this I am wondering do you have power brakes? Wonder if the booster might be starting to leak vacuum. That would be a major enough leak to kill that side of the manifold. At the very least you did find issues in the carb so all was not lost in cleaning it. Personally I do not see how a ignition problem could effect they cylinders that way and I am still leaning towards a fuel supply issue.

 

 

Lets start with some basics. In your opinion does it run OK off idle? It seems normal driving down the road no bucking backfiring etc? You have rechecked and you still have the same 4 cylinders that are dead at idle correct? Nothing changed there? Did this problem start all at once or did you notice slow changes over time that got you to this point. Have you checked compression so you have a base to work off of and if so what was it. Do you have a way to feed it propane? If so have you tried it and what did the rpm do? It should either go up or drop off I have never seen one stay the same. What is your base timing even though I do not get the feeling this is a timing issue. Have you checked to make sure the marks on the pulley have not slipped so you know your base timing is correct? They do that once in a while. If that has all checked out what are you getting for total timing advance?

Not trying to be a smart a$$ and I am guessing when you find the problem it will be something simple. It only takes 3 things for a gas engine to run correctly. Good compression, spark at the correct time, and the proper amount of fuel. As the old Mission Impossible TV show said "Your mission if you chose to accept it is" Yours is to determine which one or more of the 3 required items is on vacation. I still get the feeling it is a fuel related problem that is tied to 1/2 of the intake manifold. I am not a Ford guy in the sense I have had several of these engines tore down as I have not. Did lots of tune-up and drive-ability troubleshooting back in the 80's. But I worked at an International Harvester dealership. Do you remember their ad's? "We are the other guys". But an engine is an engine in the basics and I saw a fair share of GM, Ford, Dodge, and Jeep come through the doors too. If I am understanding correctly you have a pre-emission engine so your not dealing with EGR systems, AIR pumps and all the other early items that EPA thought we needed to contend with. Basic engine; PCV valve, 2V Ford carb. someone has added HEI but big deal you still have a mechanical distributor so you can check out the advance systems, see what they are doing and not be second guessing what the computer is telling it to do.

You're willing to bet your next 3 pay checks on the carb being clean; CORRECT? Just kidding but how did you clean it? If I have the time and especially if working on my stuff then I will try and let it soak over night in carb cleaner, then a hot water rinse, blow dry with air and then follow that with a can of spray carb cleaner going through all the passage holes and try to make sure that there is good flow and that the spray patterns match the other half of the carb. I am hoping that the forum can help you to determine what your problem is so that you can fix it without just guessing and throwing money at it. That gets expensive very fast.

The reason I asked about the carb. I am looking at buying a big farm tractor at the moment (Cat powered 325 hp articulated 4 wd). I was told the history of the tractor repairs over the past few years. I believe the work has been done as there is evidence to support it. Unfortunately I was also able to find issues with some of that work and it will require redoing. So if your absolutely sure the carb is clean then great move on and lets explorer other possibilities. If not then spend a few minutes rechecking some things on it. Again one of the very easiest ways that I know to do it is to take a propane bottle with a hose on it and feed it to the carb. You can put the hose into each venturi and see how the engine responds. If one half is working correctly and the mixture is right then you should see a drop in rpm as you give it fuel and drive it rich. However if you have a lean feeding side then when you give it fuel your going to see a rpm increase. I would guess probably a pretty good increase if your dropping 4 cylinders at idle. You can also pick-up on worn throttle shaft bushings and other vacuum leaks by running the hose around things. I like it much better around running engines over spraying carb cleaner, either, or some other flammable chemical on things. For one thing it is much easier on ones eyes and it will not discolor paint like some of this other stuff will do. Good luck in your search and keep posting what you find.

 

A local F100 club member spent 3 hours under the hood with me last night. We are both inclined to think that because I found the plumbers putty on the inside of the accelerator pump as well as the outside the outside its a good possibility there is a clog in the idle circuit. He is going to check around for a working two barrel that I can throw on just to verify its the carb.

This is how it looked

​​​​​​​

 

Yes, that could be. It definitely needs a rebuild.

 

plumbers putty on a carb /??? now I have heard everything .

 

Just when I thought I had found all problems the PO had created, another one rears its ugly head. I could go on for two hours with a list of things that he had very cleverly hidden to make the truck run and drive. Oh and did I mention about the LED light strips he had hidden in the tail lights to make the brake lights come on ??!!!

 

lol PO are very creative

 

 

Nice to know you got it nailed. Hopefully you can get the original cleaned out. This will be one you will always remember.

 

Update, got the original (not OEM but the carb that I bought it with) back on and found that I had blown the diaphragm out of the new power valve. Literally blew it up into the float bowl. Replaced the bad power valve, had to clean all the fowled up plugs due all the gas being poured into the engine and the old 390 purrs perfectly at idle.

Now the problem is I have the engine idling perfectly I can't get any throttle. When I just barely touch the accelerator to give it gas it sputters and dies. Any suggestions? Timing is spot on, each air fuel mixture is adjusted perfectly for a 700 rpm idle