Fuel Line Vent Line from Filter to the Tank

[The PIG Smith]

The stock fuel filter has an extra nipple to connect a vent line from the filter back to the tank.

That's great if you use the stock filter.
I do not plan to use that style fuel filter, opting for an inline clear glass filter with a element that can be changed or reused.

How would I plumb the vent line back to the tank with a fuel filter that does not have a provision for the vent line?

[Charles Kline]

Its not a vent, its the fuel return. without it the carb bowl would over flow since the pump is running all the time. You would do a clear filter before or after the stock one if you wanted.

[tgreese]

No, I don't think the float bowl would overflow. The earlier engines without the return don't have that problem. I believe that the return was added only to keep the fuel cooler, by circulation from the tank to the engine and back. You could plug the return and it would not affect engine operation, except in terms of vapor lock.

I agree that you could add the clear filter ahead of the factory filter. The added restriction of an additional filter should not matter.

[Charles Kline]

There is not a lot of pressure on the inlet valve of the bowl, just what the float pushes against it. ~6 psi of the mech pump could over come that I'd think.

[tgreese]

That makes sense intuitively, but I don't think there is any difference between the float valves and fuel pumps of the 70-ish engines without a fuel return line, and the later engines that have one. These earlier engines have no problems with float bowl flooding. 6 psi sounds like a lot, but the float pressure is concentrated on a very small area of the needle. Say the seat area is 1/10" in diameter, then the pressure exerted by 6 psi is about 1/4 oz. Seems pretty reasonable for the upward float pressure.

[REDONE]

Well Mr. Smith, looks like you're in a perfect position to put this to rest! Since the glass filters are only what, $12 for the name brand Holley ones? You could install it with the return line intact but unused and see what happens!

Personally, when I tried it years ago I had to many other issues with the stock carb to know if it did anything. When I installed the Holley 4bbl, I set it up with a return line.

[The PIG Smith]

Ok, but what are you doing with your tank vent or your carb bowl vent? Its literately just sitting there absorbing fuel vapor, hurts nothing. Sure it can be a vac leak if its got a bad diaphragm or bad hoses but its not the HP robber some folks worry it is.

Good point

[The PIG Smith]

Another case of "Yes, I need the Fuel Return Line" and I will have one.
As been suggested, I will install the stock filter with the return line.
Next, I will install the the glass filter between the stock filter and the carb.

[prospector]

[quote="tgreese"]I believe that the return was added only to keep the fuel cooler, by circulation from the tank to the engine and back. You could plug the return and it would not affect engine operation, except in terms of vapor lock.

That makes sense, these SJ's were plagued by vapor-lock, weren't they? I've heard vapor-lock horror stories about them for years.

[HeavyMetalThunder_81]

The vent return port on the filter is to help reduce vapor lock by having boiled fuel vapors bled off and sent back to the tank while still allowing liquid fuel to reach the carb. The vent return port must be positioned at the 12-o'clock position in order to be effective.
I use the stock fuel filter and run a glass pre-filter before my mechanical pump.

[az chip]

If I put my fuel return at 11:30, can I still post here?

[HeavyMetalThunder_81]

If I put my fuel return at 11:30, can I still post here?

If we let you do it then someone will want theirs at 10:30, then someone else will want theirs at 9, then 3...then what's next? Anarchy?!
This isn't Nam, there are rules! Has the whole world gone crazy?! Am I the only one around here that gives a **** about the rules?!



I'm joking, of course

[az chip]

I get it. Back at 12 it is. Lol.


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[fulsizjeep]

Another case of "Yes, I need the Fuel Return Line" and I will have one.
As been suggested, I will install the stock filter with the return line.
Next, I will install the the glass filter between the stock filter and the carb.

Wally has the clear glass filter installed before the stock filter.

I had a trip to Moab in April 2012 and spent the day out on Steel Bender trail. It was pretty bouncy day and by noon I had fuel problems. By 2pm it was in the mid 80s and I had a lawn sprinkler spraying fuel out of the carb. We replaced the needle and seats on the Holley 600 but they didn't last long. I came home the next morning and skipped the next 2 days of rides. Turns out the factory return was clogged in the section of steel tube. I changed the line completely with a rubber line.