Factory big block fuel system - The 1947 - Present Chevrolet & GMC Truck Message Board Network

FLYNAVY30 · 11-02-2013, 12:38 PM

Did the big block trucks come with a factory return style fuel system? Im in the middle of my motor swap and it looks like I have a pressure and return line running from the tank, all the way to the mechanical fuel pump and back. In addition, it looks like I have some kind of vent line running to the black canister up next to the battery tray on the passenger side.

Im just curious because if this is the case, I can use the pick up and return already in the tank for the fuel sytem for the new motor.

**WIDESIDE72** · 11-02-2013, 01:38 PM

Yes

**bigmac73** · 11-02-2013, 07:12 PM

black canister was a charcoal filter for fumes hooked up to a vac line,old emission set up, i would just pull it out and cap off the vent

FLYNAVY30 · 11-02-2013, 08:17 PM

agreed. Im running a carb'd LS1. Im planning on a 6-AN line through the electric pump to the regulator, up to the carb. I was planning on a 4-AN line for the return from the regulator to the tank. Any thoughts? The return port on the regulator is 6-AN, but I thought that was probably far bigger than necessary on my very mild, carb'd build.

**bigmac73** · 11-03-2013, 07:02 AM

i don't think the size of the return line would matter, it all depends on the regulator setting,
I take it you have relocated the tank to the rear of the truck and everything has AN fittings

FLYNAVY30 · 11-03-2013, 08:20 AM

Its actually in a '72 C20 Suburban so the tank's already in the rear....I just post over here when Ive have nonmodel specific questions since this side gets a little more traffic. Regulator will be around 7-8 PSI

**bigmac73** · 11-03-2013, 09:41 AM

well i don't know what the ID is for a AN-6 or 4, I think a AN 6 is close to a 3/8 fuel line, so 4 would be close to a 5/16 i think that is a stock return line size,
but with a Elec pump might put out a lot more flow so i would go with a AN 6

**bigmac73** · 11-03-2013, 09:42 AM

P.S
throw some pics out of the burb, I don't think I have seen one driving around town

**chiefcfd** · 11-03-2013, 09:48 AM

Just FYI AN hose and fittings. Hose is sized in 1/16 ID so each number is the number of 16ths of hose. Just wanted to pass this on.

-4= 1/4
-6=3/8
and so on.

FLYNAVY30 · 11-03-2013, 10:30 AM

**bigmac73** · 11-03-2013, 02:29 PM

I like it Looks good

11-02-2013, 12:38 PM	#1
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Factory big block fuel system Did the big block trucks come with a factory return style fuel system? Im in the middle of my motor swap and it looks like I have a pressure and return line running from the tank, all the way to the mechanical fuel pump and back. In addition, it looks like I have some kind of vent line running to the black canister up next to the battery tray on the passenger side. Im just curious because if this is the case, I can use the pick up and return already in the tank for the fuel sytem for the new motor.

11-02-2013, 01:38 PM	#2
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,500	Re: Factory big block fuel system Yes

11-02-2013, 07:12 PM	#3
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Factory big block fuel system black canister was a charcoal filter for fumes hooked up to a vac line,old emission set up, i would just pull it out and cap off the vent __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

11-02-2013, 08:17 PM	#4
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Re: Factory big block fuel system agreed. Im running a carb'd LS1. Im planning on a 6-AN line through the electric pump to the regulator, up to the carb. I was planning on a 4-AN line for the return from the regulator to the tank. Any thoughts? The return port on the regulator is 6-AN, but I thought that was probably far bigger than necessary on my very mild, carb'd build.

11-03-2013, 07:02 AM	#5
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Factory big block fuel system i don't think the size of the return line would matter, it all depends on the regulator setting, I take it you have relocated the tank to the rear of the truck and everything has AN fittings __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

11-03-2013, 08:20 AM	#6
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Re: Factory big block fuel system Its actually in a '72 C20 Suburban so the tank's already in the rear....I just post over here when Ive have nonmodel specific questions since this side gets a little more traffic. Regulator will be around 7-8 PSI

11-03-2013, 09:41 AM	#7
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Factory big block fuel system well i don't know what the ID is for a AN-6 or 4, I think a AN 6 is close to a 3/8 fuel line, so 4 would be close to a 5/16 i think that is a stock return line size, but with a Elec pump might put out a lot more flow so i would go with a AN 6 __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

11-03-2013, 09:42 AM	#8
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Factory big block fuel system P.S throw some pics out of the burb, I don't think I have seen one driving around town __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

11-03-2013, 09:48 AM	#9
chiefcfd Senior Member Join Date: Oct 2010 Location: Cadiz, Ky Posts: 514	Re: Factory big block fuel system Just FYI AN hose and fittings. Hose is sized in 1/16 ID so each number is the number of 16ths of hose. Just wanted to pass this on. -4= 1/4 -6=3/8 and so on. __________________ 1972 Chevy LWB Roadster 1999 Chevy Silverado 2wd 2015 Chevy High Country 4x4 Crew Cab

11-03-2013, 10:30 AM	#10
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Re: Factory big block fuel system

11-03-2013, 02:29 PM	#11
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Factory big block fuel system I like it Looks good __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

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