Carburetor vacuum lines. 79 Ford Holiday Rambler

[79 Rambler]

Hey everyone. I purchased a 1979 Ford Holiday Rambler with the 460 motor, going on a year and a half ago. I bought it for $500, it needs a complete remodel on the interior and the guy I purchased it from said he hasn’t been able to get it started in the 5-8 years he has owned it. After I bought it I discovered he had the battery terminals on the wrong post, I switched them and replaced the ignition coil and ignition module and it fired up with a little gas poured into the carb. Since then I have done a lot of work on it to make it road worthy but I am still struggling with it running very rough. I have replaced the plugs, plug wires, battery, ignition module, ignition coil, alternator, fuel pump, rebuilt carb, shocks, tires, belts, water pump, thermostat, valve covers, distributor and cap/rotor, hoses, PCV valve and grommet, master cylinder, all brake components, all fluids and filters, and I changed the exhaust manifold on one side and attempted the other side but I busted a bolt attempting to take it off.

With all that being said, I have numerous vacuum lines that don’t go anywhere and are just randomly appearing as I am going through everything. I have bought the book for the Holley carburetor (its model 4180) and for the Ford chassis for that year. Everyone I speak with in my area are a little lost when it comes to carburetors and so I am unable to find out what all the vacuum ports on this carburetor lead to. Few people I have spoken to have told me if its running rough then I could have a vacuum leak, so I have been trying to find out where everything goes and haven’t had any luck. I also have two vacuum canisters that aren’t connected to anything. I have an idea of where some of the lines lead to but not sure which ports. PCV valve, distributor, intake manifold, master cylinder, cruise control and I'm sure a lot more than that. I am hoping that there is another person on here who owns the same RV as I do and would be able to shed some light on where all the vacuum go to. Thanks

[select55]

Originally Posted by 79 Rambler

Hey everyone. I purchased a 1979 Ford Holiday Rambler with the 460 motor, going on a year and a half ago. I bought it for $500, it needs a complete remodel on the interior and the guy I purchased it from said he hasn’t been able to get it started in the 5-8 years he has owned it. After I bought it I discovered he had the battery terminals on the wrong post, I switched them and replaced the ignition coil and ignition module and it fired up with a little gas poured into the carb. Since then I have done a lot of work on it to make it road worthy but I am still struggling with it running very rough. I have replaced the plugs, plug wires, battery, ignition module, ignition coil, alternator, fuel pump, rebuilt carb, shocks, tires, belts, water pump, thermostat, valve covers, distributor and cap/rotor, hoses, PCV valve and grommet, master cylinder, all brake components, all fluids and filters, and I changed the exhaust manifold on one side and attempted the other side but I busted a bolt attempting to take it off.

With all that being said, I have numerous vacuum lines that don’t go anywhere and are just randomly appearing as I am going through everything. I have bought the book for the Holley carburetor (its model 4180) and for the Ford chassis for that year. Everyone I speak with in my area are a little lost when it comes to carburetors and so I am unable to find out what all the vacuum ports on this carburetor lead to. Few people I have spoken to have told me if its running rough then I could have a vacuum leak, so I have been trying to find out where everything goes and haven’t had any luck. I also have two vacuum canisters that aren’t connected to anything. I have an idea of where some of the lines lead to but not sure which ports. PCV valve, distributor, intake manifold, master cylinder, cruise control and I'm sure a lot more than that. I am hoping that there is another person on here who owns the same RV as I do and would be able to shed some light on where all the vacuum go to. Thanks

Take a can of carb clean ; spray it around the intake port areas of the intake manifold. If it revs up a bit and or smooth's out for few seconds its a leaking intake gasket,.This was very common on a 460 of that era
regarding vacuum canisters were for things like emission vapours from fuel tank and back up vacuum to heater controll etc

[tderonne]

It could be just a vacuum leak, definitely worth investigating.

Let me throw something else in the mix for you to think about.

Timing chain. Ford retarded the cam a bunch (8°?) to meet emissions back then. Add in some chain slop/stretch and the cam can be WAY behind where it'd like to be. Put fresh timing chain set (with the pre-emissions gear) in a buddy's 1976 Holiday Rambler. Advanced the cam about 20°. It went from "Why does this thing run so bad?" To "Wow!"

[79 Rambler]

I have tried spraying some carb cleaner around the intake manifold and around random vacuum lines I find and cant really hear to much of a different. there are some lines that come off of the carb that are just cut off, then some lead random places and then aren't connected to anything or near anything that I could see them connecting to. I also have a big port that comes off of the intake manifold that has around 5 ports that come off of it, that have more lines that lead nowhere.

[79 Rambler]

I am not the most mechanical guy haha, simple replacing of something is where I tend to be the best at. I wouldn't even know where to begin with the timing chain. I am still trying to find someone with a vacuum gauge who can come and adjust my carb so it is getting the best vacuum lol. But doing my best to find out where all the lines go and everything else prior to trying to get the best vacuum.

[tderonne]

Oh yeah, if you have the manuals, you have the emissions hose routing diagram, right? Googling actually finds one, no telling exactly how the motorhomes were setup though.

[select55]

Originally Posted by 79 Rambler

I am not the most mechanical guy haha, simple replacing of something is where I tend to be the best at. I wouldn't even know where to begin with the timing chain. I am still trying to find someone with a vacuum gauge who can come and adjust my carb so it is getting the best vacuum lol. But doing my best to find out where all the lines go and everything else prior to trying to get the best vacuum.

the timing chain idea is right about timing advance ;; helps with low end take off power and mid range however it won make the engine have a rough idle

[eddieelk]

Do you have a Haynes or Chilton manual on that year Ford car or truck. It should have a vacume routing picture for the 460. Eddie Elk.

[twinboat]

Pull off the dist. cap and watch the rotor as you bar the engine over, back and forth. The rotor should move, within a few degrees of the crank, if the chain is tight.

Another test of intake gaskets is to pull the PCV valve. Cover both valve cover holes with your hands, while running. If a vacuum is felt, the gaskets may be leaking internally.

[select55]

Originally Posted by twinboat

Pull off the dist. cap and watch the rotor as you bar the engine over, back and forth. The rotor should move, within a few degrees of the crank, if the chain is tight.

Another test of intake gaskets is to pull the PCV valve. Cover both valve cover holes with your hands, while running. If a vacuum is felt, the gaskets may be leaking internally.

the chain wont be tight on a engine thats run a bunch of miles so means nothing your always going to get play testing this way on any old engine and you cant check for a vacuum leak that way at all

[79 Rambler]

Yes I have purchased the book for the vehicle and for the carburetor I have. There are around 30+ different vacuum layouts, and because I'm not the most mechanical person I am not positive what half of the stuff on the diagrams are or which one to go off of. I guess I was hoping to find someone who had the same RV as I do and would be able to send some picture of where they have their lines connected to.
I got lucky enough to find some pictures online of where everything is supposed to be connected, and I called Holley and asked them about what all needs connected to this carburetor and they gave me conflicting info 😂. So now I'm hoping someone has the same year and model and will be able to shine some light on this problem.

[select55]

Originally Posted by 79 Rambler

Yes I have purchased the book for the vehicle and for the carburetor I have. There are around 30+ different vacuum layouts, and because I'm not the most mechanical person I am not positive what half of the stuff on the diagrams are or which one to go off of. I guess I was hoping to find someone who had the same RV as I do and would be able to send some picture of where they have their lines connected to.
I got lucky enough to find some pictures online of where everything is supposed to be connected, and I called Holley and asked them about what all needs connected to this carburetor and they gave me conflicting info ��. So now I'm hoping someone has the same year and model and will be able to shine some light on this problem.

one thing to make sure of if this thing runs as bad as your saying that u don't have any vacuum at idle or off idle at the egr valve

[79 Rambler]

I honestly just figured out what the EGR was about a month ago and hooked a vacuum line up to it and didn't really change how it ran.

[79 Rambler]