The Stovebolt Site Forums The Shop Area Engine Shop Fuel Line fittings size question (Carb & Pump)

Today I fired my engine up for the first time! Seems to have a nice idle but I noticed I'm dripping fuel at the fittings in 2 places, the fittings that connect my fuel line to the Pump & Carb. I have new Stainless Steel fuel lines purchased from Inline Tube. The website says the lines are 5/16, I'm guessing that refers to the line itself and not the Male Connectors. Those to my eye appear to be 7/8. Anyway, I have the original brass fittings on my truck that step down the size to what appears to be 5/8?? These connect to the pump which I purchased at BowtieBits.com and carb which is a Carter YF. So I'm guessing the new fuel lines don't like my old fittings (they are almost 70 yrs old now) Does anyone know where I could buy these Brass Fittings, and can you point me to the correct size, it seems the fuel line male thread is 7/8 and needs to step down to about 5/8, but alas hoping someone knows what the exact inlet (female) size is on the Fuel Pumps and Carter YF Carbs. Thanks!

Do you have a NAPA nearby? They usually carry an assortment of brass fuel fittings. Take yours off and match them to some new ones.🛠

Try backing the line nut off and applying some silicone grease to the back of the taper and the threads of the line nut. Then while holding the brass nipple, really tighten down the lines. Stainless steel takes more effort to seal then the softer steel/hybrid lines do. The grease will keep the stainless from seizing.

Joe

You might want to check with the supplier of the fuel lines.

Normal fittings are 45 degree. Fittings for stainless are 37 degrees. They are not compatible.

Generally the Carter YF carbs have a female 1/8 pipe.

Jon.

Whenever I deal with new stainless lines (specifically from Inline), I make sure that the old fittings are spotlessly clean and not galled.
I then tighten them and loosen them repeatedly. If you pay attention during this process, you will observe the gradual progression of the nut turning further as you go.
This occurs without actually increasing the amount of torque being applied on each successive tightening sequence.
What you are observing is the stainless steel flare becoming form-fitted to the brass fitting.
If you try to tighten these lines in only one gorilla-like step, you risk galling of the stainless steel flare. Stainless steel is notorious for galling.
Carl

Besides following the procedure described by Carl, I also use stainless-steel-fitting grease (anti-seize compound).

Tim/Carl, thanks for this info. On the Stainless steel line, do I apply some of the anti-seize compound on the inside face of the trumpet head steel line or around the outside collar/neck of the steel line that is inside the nut, or do both? I will try your advice this weekend. Also, not sure if it is overkill but i went ahead and ordered a new set of fittings from Jim Carter's Old Chevy Trucks. After looking at my original 1948 fittings more closely, they don't have a smooth mating surface/face for the trumpet head of the stainless steel fuel line to press up against. I tried soaking in soap and water for days, tooth brush,etc...but there is an old layer of dark, dirty brass patination inside each one.

OK, don't laugh, but get a packet of hot sauce from Taco Bell and squirt it inside of the brass fitting, then rinse it off after 5-10 minutes . If it is just caked with tarnish deposits, the hot sauce should clean it off just like it works on copper pennies.

Thanks Carl, I'll give it a try, won't throw anything away. But at the same time, hoping the new ones I ordered will do the trick with the anti seize.