74' f.5 VSV/fuel disambiguation (1 Viewer)

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Location
Marietta, GA
I have a 74' f.5 with a weber carb. I was hoping to put this off for a while, but I noticed when putting fuel in the tank for the first time yesterday there was a lot of negative pressure in the tank when I took the gas cap off, so i started reading the threads and I did not want to go the vented gas cap route since the charcoal canister is still in the system. In following the wiring I noticed the VSV is not functioning and has some, but not all, wires connected. Pictures to follow, but my questions are:

1. Can I take the feed from the charcoal canister that used to feed the VSV and put it directly on the intake manifold? - is this safe, will this allow my tank to pull pressure back and fumes to go where they need to or is there a better way?

2. There are two lines that go from the front of vehicle facing side of the vsv to a junction on the intake manifold- Remove and plug?

3. All the lines in the system, specifically the lines above the tank look super old- what is the priority to replace?

4. Under the vehicle at the front of the leaf sprint is what I think is a fuel filter or a check valve. How to tell the difference?

And as always, if you see something glaring that needs to be addressed- feel free to let me know (I know you will anyway!).

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I am far from an expert, but what I would do before you do any more driving is get that rubber fuel line and fuel filter far away from the manifolds. Those exhaust manifolds get hot and if they melt that rubber line you've got gas on hot manifolds--bad, bad news. Maybe change to metal fuel line to the carb and put the fuel filter in its proper location on the other side of the engine. Take it from me, having your truck spontaneous catch on fire while your driving is no fun (you can see my build thread to see what I mean. Granted it was a jeep and not a LC, but still).
 
I am far from an expert, but what I would do before you do any more driving is get that rubber fuel line and fuel filter far away from the manifolds. Those exhaust manifolds get hot and if they melt that rubber line you've got gas on hot manifolds--bad, bad news. Maybe change to metal fuel line to the carb and put the fuel filter in its proper location on the other side of the engine. Take it from me, having your truck spontaneous catch on fire while your driving is no fun (you can see my build thread to see what I mean. Granted it was a jeep and not a LC, but still).

Thank you for the info, looks like the fuel line just jumped to the main priority. I read through your build - Marion is looking great!
 
Some recommend venting the canister to atmosphere. I added a filter off of the soft line on the passenger side to keep wildlife out, but to get rid of fumes. Others have suggested running a line to the air cleaner.

My Weber kit for my pickup uses an OE purge valve charcoal can combo. The purge valve is operated in the presence of engine vacuum, so all the fumes don't build-up in the intake manifold while the truck sits. It probably has an orifice in its internal plumbing to keep the full manifold vacuum from creating negative pressure in the tank. Intake backfire could be a problem, maybe a PCV valve could be rigged as a flame arrester.

I could probably get you more information, but my answer, basically, lacks real knowledge or engineering.

During the course of a year of my Cruiser sitting with gasoline at high altitude, I put about less than a gallon of gasoline in the tank, and two days ago, drained about a quart of it; I'm sure I could have got more if the tank wasn't on a slope. Basically, the cab creates this greenhouse environment that heats up the tank, but I wouldn't be surprised if I didn't loose a gallon a year to evaporation.

On some FJ40s there is actually a line that terminates into the body, somewhere under the passenger cowl or floor. I wonder if that is clogged with our classic Cruiser mud dauber wasps, and creating negative pressure in the context of a closed VSV, but I admit that I don't fully understand the line's function in relation to the OE canister.
 
If you are running a Weber carburetor, you are not smog legal, so why would you retain ANY of the emissions equipment, why not totally de-smog ???
 
noticed you have a vent on your valve cover.... with a weber this should be plumed into the inside of your air cleaner... looks like you have an airbox... probably does not have a provision for this on the plenum either ... you will have a much happier engine if you do

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noticed you have a vent on your valve cover.... with a weber this should be plumed into the inside of your air cleaner... looks like you have an airbox... probably does not have a provision for this on the plenum either ... you will have a much happier engine if you do

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Thank you for the input on this- I am still trying to figure out which way to go from the PO's snorkel addition. I think returning back to an air cleaner is going to be a better way to go...
 
@JohnnyC I think I have two lines from the VSV that are incorrectly hooked to the intake manifold (plenum?) in the picture below that I could use. Also in the second picture, this is my pcv valve right?



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1 last question- If I bypass the snorkel, would a circular air intake work and allow for hookups to the valve cover or am I looking for something specific? I have not taken a look at the carb and air intake system yet.
 
Yes, that is the PCV circled in red. The two lines to the intake manifold from the VSV would best be capped with an OEM (sorry, I don't know the part #, but the off-the-shelf ones at the auto store are really bad) vac cap, or the hole in the intake capped with a pipe-thread plug.

Because, you have a power steering pump, you might have trouble mounting the '74 and earlier air cleaner assembly? The 2F air cleaner wouldn't work with the '74 intake manifold; it locates the carb closer to the head than the 2F intake manifold. The Weber air cleaner isn't bad, but, the elbowed barb for the hose to the PCV in the valve cover is kinda cheap, but I'd go that route unless I knew that the power steering isn't in the way.
 
Yes, that is the PCV circled in red. The two lines to the intake manifold from the VSV would best be capped with an OEM (sorry, I don't know the part #, but the off-the-shelf ones at the auto store are really bad) vac cap, or the hole in the intake capped with a pipe-thread plug.

Because, you have a power steering pump, you might have trouble mounting the '74 and earlier air cleaner assembly? The 2F air cleaner wouldn't work with the '74 intake manifold; it locates the carb closer to the head than the 2F intake manifold. The Weber air cleaner isn't bad, but, the elbowed barb for the hose to the PCV in the valve cover is kinda cheap, but I'd go that route unless I knew that the power steering isn't in the way.

Thank you for the clarification on the PCV and the two VSV lines. I think a threaded plug is going to be the way I head. In keeping the snorkel is there a downside to using an inline filter?
 
An air filter, looking at something like a Spectre performance 9831
 
I never understood snorkels, personally. Parts such as the distributor, transmission shifter, etc. are open to atmosphere, and could need attention after taking a swim. The engine castings would best be not quenched, in a metallurgical sense. I understand maintaining the look if you already have the hole in the body. I also know that I probably wont wheel my 40 nearly as hard as others, in general.

One problem with downdraft carbs, in general, is getting air to turn the sharp corner at the air horn. And, the 38/38 Webers are actually smaller in throat then the stock carbs. So, if I was to make one move to get more fuel in, at particularly, higher rpm, I'd go with this if you can accommodate the space. It is hard wading the options of intake on the web or aftermarket. They kinda suggest that more air=more air. But with a carb, more flow thru the throat means more venturi, and more fuel. In EFI, it is all controlled by the computer. Is there something wrong with the current set-up?
 

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