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Return fuel line installed

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  • JoeHall
    replied
    Originally posted by mw2013 View Post

    how do you assure water jacket in engine is clear? flush?, if not what happens? hot spots? is this a Studebaker only issue?
    From what I could see of yours, through the freeze plug hole pic you posted, it appears yours haven cleaned, and cleaned well. JMHO

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  • altair
    replied
    I am not opposed to a fuel return line, but I nave difficulty understanding the merit in the assembly. I assume it is something to do with the fuel boiling in the fuel line/pump etc. What ever is on one side of the diaphragm in the pump will be delivered to the other side be it air/vapor or liquid. I performed an experiment with a fuel pump by placing an attached 10 foot length of hose into a container of a hydrocarbon/solvent and stood on a 10 foot ladder and actuated the lever and 5-6 strokes there was fuel delivered to the out let with a 6 foot stream. My point is the fuel pump will move vapor as well as liquid. If for some reason the fuel was to boil in the pump it would not take any more than a few strokes to clear said vapor and replace it with liquid fuel from the tank.

    After extensive discussions with a journeyman carburetor service person we concluded that the engine failure was caused from over fueling ie fuel boiling in the carburetor bowel and overflowing down the throat and over fueling the engine. Continuing to actuate the starter only worsens the condition as more fuel is delivered to an already over fueled engine. The usual procedure for this "condition" is to wait for the high temperature to reduce somewhat, but what is really happening is the excess fuel is evaporating to a point where it will restart. These engine failure conditions are frequently referred to as "vapor lock". To date I have not had it explained to me what a "vapor lock" is and what really causes it. From my understandings, the conditions of fuel boiling is in the carburetor, and not in the fuel pump. The most common factors that cause boiling fuel is elevated temperatures. Engine cooling systems are a fixed operation, eg fans, radiators circulation water pumps and a quantity of liquid to transfer the generated heat to the radiator where it is air cooled.
    Engine operating temperatures can be controlled by variable temperature thermostats. Too high of a thermostat can be detrimental in warmer air temperatures. In sufficient liquid coolant in the block can also cause increased engine temperatures, this can be as a result of debris in the block or poor maintenance and low level of liquid. Slightly retarded timing can also contribute to higher temperatures. If you bring all of these issues together at the same time, low coolant, high thermostat, slightly retarded timing , 100* air temperatures, restricted radiator and low speeds you will most likely become a victim of "vapor lock", perhaps a return fuel line will fix it.

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  • Felix
    replied
    P.S. I also run a return line. The setup has a 100 micron filter between the tank and electric pump, a regulator with return line, a 10 micron filter before the carb. The return line dumps into the tank on the opposite side, where the station wagon filler would be fitted. The regulator may not have been necessary, as the pump puts out 7psi max, but with the return line it made the job easier and with the constant flow I have cooler fuel.

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  • skyway
    replied
    Presuming you’ve not yet replaced your core plugs, you dig & flush all the muck out through those openings. For me a coat hanger & a hose and/or power washer are the tools of choice. It’s a nasty dirty job but you’ll only have to do it once.
    ...and yes, the muck will be worse toward the (lower) rear of the block.
    Oops, Felix beat me to it!

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  • Felix
    replied
    The best way is assure the water jackets are clear is to have a bare block and all the freeze/expansion/core plugs removed. At this point one takes what ever rod/wire/pokey thing and poke, scrape, scratch all the rust, muck, dirt and sand out from the spaces between the bore walls and the floor of the water jacket. Flush with copious amounts of water. Depending on condition it could take a day or two of hard work. It could be less time but don't stop half way. If it's in good condition you wouldn't be doing this.

    I have put blocks in tanks and used different methods to clean them but by far the most reliable method to remove the crud is by hand. Once one gets the idea and technique down it can be an enjoyable process.

    It is not unusual to remove 10 -20 pounds of crud/rust/mud and to find the spaces between some bores filled 1/4 or 1/2 way up the bore wall, especially at the rear cylinders. This is probably the main cause of warmer than wanted engine Temps.

    Cleaning the spaces while the engine is in the car is harder and one can't get to all the nooks and crannies but it can be done well enough so it is not an issue. I've done this before and removed whatever water jacket plugs I could get to. No issuse after so it must work effectively enough doing it in the car.

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  • mw2013
    replied
    Originally posted by Bullet View Post
    I have a return line AND and electric pump on my 64 Cruiser. As stated since installing these and insuring my water jackets in the engine are cleared, no more vapor lock.

    Mark
    how do you assure water jacket in engine is clear? flush?, if not what happens? hot spots? is this a Studebaker only issue?

    Leave a comment:


  • Bullet
    replied
    I have a return line AND and electric pump on my 64 Cruiser. As stated since installing these and insuring my water jackets in the engine are cleared, no more vapor lock.

    Mark

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  • Son O Lark
    replied
    Update: Today is in the 90 degree temperature range here in Indiana. No problem for the Possum Smasher. I am now looking forward to some hot cruisin' this summer.

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  • Son O Lark
    replied
    Originally posted by altair View Post
    My question is what is the purpose of the fuel return line?
    A fuel return line allows the pressure of vapor lock to be relieved.

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  • Buzzard
    replied
    Barry,
    Thanks for sharing this great idea.
    Bill

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  • altair
    replied
    I enjoy doing various projects on my car, I have two 6 volt batteries, one would do, I have a four barrel carburetor, a two barrel would work ok, I have two fuel filters, whereas one would do. My question is what is the purpose of the fuel return line?

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  • Mridgway
    replied
    Can a return line be used with an electric fuel alone? Would it be of any benefit?
    Marshall

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  • Paul Keller
    replied
    I have seen anywhere from .032 - .045 restrictors recommended. The above hint to test fuel pressure is definitely worthwhile.
    paulk

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  • JoeHall
    replied
    My experience with those filters is that the PR valve inside soon grows weak, then line pressure drops, and fuel starvation begins.. An in-line restrictor is a permanent fix. With a 1/4" return line, and the .035" restrictor, it still pushes a stream nearly all the way across the fuel filler neck.
    Last edited by JoeHall; 07-23-2021, 08:17 AM.

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  • r1lark
    replied
    Originally posted by JoeHall View Post
    You might wanna install an in-line restrictor, lest the motor starve for fuel under heavy load conditions. I used a Harley carb jet, that fits inside the line perfectly, and has about .035" hole in center.
    Joe has a good point. But Barry, check this filter first to see if there is already a restriction on the return connection. Pretty much all of these types of filters I have used have a orifice visible in that return connection.

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