Hi All,
I bought a 1977 F100 a few months back and use it as my daily driver. I am new to all this but have great neighbors that have been a huge help. I've also been reading as much as I can find. The truck has had all the emissions stuff removed and the only thing hooked up was the distributor. I have performed some of the simple maintenance: new vacuum plugs for all open ports (I have no idea how it ran), new spark plugs and cables, new coil, oil and filter change, connected the PCV system back up with inline air oil/ water remover, changed air filters, two new fuel filters (one inline and one on carb), rigged up a new choke heater tube, lubed chassis, adjusted clutch and a few other things not worth mentioning. The previous owner also installed a new gas tank but I think its non-vented so I bought a new vented gas cap.

The main issue I have been having is hard hot starts but now I'm worried I have other issues. This weekend I decided to learn how to check the timing and wanted to see if there was a difference between using the ported vs non-ported vacuum. I have read all sides of this debate and mine is a manual transmission and it is connected to a ported connection. While performing the timing I saw very little change when I increased the RPMs which I think means my mechanical advances is not working. When I connected my vacuum advance the timing increased immediately after throttle up to around 34 - 35 from around 12. My vacuum pressure is around 10. The truck idles great but is a bit sluggish which I now think is my mechanical not working when the vacuum is low. Now the other issue is when I went to switch to the manifold vacuum port I noticed fuel was dripping out the port. The engine was off and usually that port is capped. A few months back before I capped all the ports a considerable amount of fuel leaked out on startup. Which prompted the capping of ports and tightening of all bolts. I had not seen it again until yesterday.

My question now is what would cause fuel to leak out of the vacuum port? My external carb bowl vent is capped also. Pics are below. I would also love any other suggestions if people have them.

Thanks in advance,
Kyle

My truck and the neighbors

The leak below is power steering. Fixed!



The blue port is the one that is leaking

This is where the distributor is connected

 

Getting a new Engine Control Module might also help. It's that aluminum do-dad tight behind the jack mounted on the inner fender. They are notorious for "silent" failures. Take care removing the wires as the connectors are usually brittle from age and easily broken.

 

There is definitely something going on with that carb. Fuel should not be leaking there. Has any thing been done to the carb to your knowledge? Some of those more schooled on that will probably chime in.

 

Hey, Nice Truck
The biggest problem when the PO abandoned the emissions system he didn't tell us if he had addressed the distributor timing after he abandoned the emissions. Is the EGR plate still under the carb? This is the Autolite 2150 we're looking at ? Was the timining chain set by the previous owner changed out ? Let's start there..

 

Hey thanks for the replies. I'll go ahead and add the control module to my current wish list. To answer the other question, I am not sure exactly what the PO had done. He did happen to mention his son was the last driver and was driving 90 in a 45 and blew out the carb. He said the truck was leaking like a sieve. He told me he fixed all the leaks and took the truck to a mechanic to fix the carburetor. It then sat in his driveway the last year and would drive it once a month.

I have been trying to figure out what type of carb it is. It says certified rebuilt but after reading the internets it looks to me to be an Autolite/motorcraft 2150. I think the EGR plate is still installed but not 100% sure. I think I attached the PCV to the port in the front of the EGR plate. I also have no clue if they set the timing. I attached a couple more pics.

 

 

Take the red cap off the top of the carb. That's where the fuel bowl vents. You are probably getting fuel out the blue port because the gas is getting hot in the bowl and expanding out into the intake after the engine is shut off.

You can leave the cap off the vent bowl and just let the carb breathe. All the older carbs were just vented to the atmosphere. Or, you can run a hose somewhere it won't pick up dust and dirt, or near spark, and let it hang open. Maybe put a small engine fuel filter into the hose end if you're worried about anything getting into the hose.

 

I definitely agree with the boiling gas at shut off problem. Holley makes a gasket that comes out underneath the bowl if your PVC connection is in the rear of the carb.

 

Should there be that big of gap between the egr and the egr plate?

 

Good call That definitely needs to be looked at.

 

That could cause a healthy vacuum leak.

 

My choke is electric which is hooked up but the choke heater tube was not there. The original ports on the exhaust were all rusty and I did not want to try to tap them out and Im sure the filter is probably clogged. So I jimmy rigged a copper pipe on top of the manifold hoping that it will get hot enough. Pic below. I am also worried the choke isn't closing when hot after one pump of the throttle. I noticed yesterday when doing the timing but haven't confirmed that yet.

I read a thread about the external bowl vent, which was a heated debate and went back and forth about how the vent worked and if it was needed or not. It was also about hard hot starts. My conclusion from that thread was that it was probably not needed because of the internal vents. But I tried venting it anyways for a day to see if it fixed the hard hot starts and it didn't. I've been trying to minimize the smell so I put the cap back on. I am in Texas and it gets really hot so maybe I will vent it with a tube attached.

Now this gap under the EGR I am not aware of. Are you saying that there should be a gasket under the EGR plate?

 

See the arrow in picture, Also see here for proper adjustment of your 2150 and more.

 

Thank you for clarifying that redrode.
Another question. Do you have a pcv valve in the passenger side valve cover and how sharp is the bend in the hose going to the air cleaner?

 

Thanks Redroad!
I will study how to do the settings tonight. Ill look into the EGR gap as well and see if I can find that on the internet. I was able to tighten the bolt holding the EGR valve down. Do yall recommend trying to reconnect the EGR system? Again I have read quite a few debates on that subject.