1/2" Fuel Line Gas Tank? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

'70 C/10 SS500 · 08-17-2004, 06:46 PM

I've heard that BB equipped trucks came with 1/2" fuel lines. I suppose then that the fittings on the gas tank would be 1/2" as well. I'm getting ready to do a complete overhaul of my fuel system because my truck was originally I6-250 powered. The 5/16" fuel lines trying to feed my swapped 500cid Caddy motor are too small IMO, and I'm going to go bigger. My questions are:

1. Is it true that I6 vs. BB truck's gas tanks have different sized FITTINGS for the fuel line coming out of them? If yes, I'd hate to re-use my old tank and have a small 5/16" outlet trying to feed 1/2" lines from a transition just outside the tank. Sounds kind of silly to have any choke point at all if I'm going through all this trouble, gotta get rid of ALL the old 5/16" stuff!

2. If question #1 is true, then where, other than the wrecking yards, can I find a BB / 1/2" fuel line gas tank? Are they available new?

3. Are the return lines different depending on size of motor, or all they all 5/16"?

I just thought about this....When I say fittings or outlet, I guess that is in actuality the Sending Unit, right? That is the pickup point for fuel to leave the gas tank right? So, are there different sized sending units?

I'm sure this will all be cleared up quick, enough rambling and nose bleeding!
Please give some input to clear some of this up for me, thanks!

68 Suburban · 08-17-2004, 06:52 PM

I do believe the size would be 5/8's.

**john** · 08-17-2004, 07:01 PM

350's and bb's had 3/8 fuel line . sixes had 5/16. I guess you could just put the right sender in it. John

Sweet72 · 08-17-2004, 09:27 PM

Setting the record straight, the inline 6 and 307 had 5/16 lines. It would seem to be a big waste of time and money to go to 1/2 when the fuel tank pickup tube is only 3/8.

**kwmech** · 08-17-2004, 09:32 PM

My 79 big block tow truck has a 1/2 fuel line but about 2'' from the end near the pump it flares back down to 3/8''.

flatblackclassic · 08-17-2004, 10:05 PM

Just throw a new sending unit in there that has 3/8 line. Problem solved

08-17-2004, 06:52 PM	#2
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	I do believe the size would be 5/8's. __________________ Just sitting here contemplating contemplation.

08-17-2004, 07:01 PM	#3
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	350's and bb's had 3/8 fuel line . sixes had 5/16. I guess you could just put the right sender in it. John __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

08-17-2004, 09:27 PM	#4
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Setting the record straight, the inline 6 and 307 had 5/16 lines. It would seem to be a big waste of time and money to go to 1/2 when the fuel tank pickup tube is only 3/8. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

08-17-2004, 06:46 PM	#1
'70 C/10 SS500 Registered User Join Date: Jun 2003 Location: Chandler, AZ Posts: 130	1/2" Fuel Line Gas Tank? I've heard that BB equipped trucks came with 1/2" fuel lines. I suppose then that the fittings on the gas tank would be 1/2" as well. I'm getting ready to do a complete overhaul of my fuel system because my truck was originally I6-250 powered. The 5/16" fuel lines trying to feed my swapped 500cid Caddy motor are too small IMO, and I'm going to go bigger. My questions are: 1. Is it true that I6 vs. BB truck's gas tanks have different sized FITTINGS for the fuel line coming out of them? If yes, I'd hate to re-use my old tank and have a small 5/16" outlet trying to feed 1/2" lines from a transition just outside the tank. Sounds kind of silly to have any choke point at all if I'm going through all this trouble, gotta get rid of ALL the old 5/16" stuff! 2. If question #1 is true, then where, other than the wrecking yards, can I find a BB / 1/2" fuel line gas tank? Are they available new? 3. Are the return lines different depending on size of motor, or all they all 5/16"? I just thought about this....When I say fittings or outlet, I guess that is in actuality the Sending Unit, right? That is the pickup point for fuel to leave the gas tank right? So, are there different sized sending units? I'm sure this will all be cleared up quick, enough rambling and nose bleeding! Please give some input to clear some of this up for me, thanks!

08-17-2004, 09:32 PM	#5
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,628	My 79 big block tow truck has a 1/2 fuel line but about 2'' from the end near the pump it flares back down to 3/8''.

08-17-2004, 10:05 PM	#6
flatblackclassic Registered User Join Date: Mar 2004 Posts: 210	Just throw a new sending unit in there that has 3/8 line. Problem solved



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