Why do people block fuel return lines??
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
rajsid:
It all depends on what carb you have in regards to the cfm, jets and how you are going to drive it. Just do nto want to starve it for fuel. I will check, unless somebody has the info already, on how many cfm the factory pumps deliver. I will get back to you tomorrow, or like I wrote, somebody has done this and has the "trick"
"DUB"
It all depends on what carb you have in regards to the cfm, jets and how you are going to drive it. Just do nto want to starve it for fuel. I will check, unless somebody has the info already, on how many cfm the factory pumps deliver. I will get back to you tomorrow, or like I wrote, somebody has done this and has the "trick"
"DUB"
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
rajsid:
It all depends on what carb you have in regards to the cfm, jets and how you are going to drive it. Just do nto want to starve it for fuel. I will check, unless somebody has the info already, on how many cfm the factory pumps deliver. I will get back to you tomorrow, or like I wrote, somebody has done this and has the "trick"
"DUB"
It all depends on what carb you have in regards to the cfm, jets and how you are going to drive it. Just do nto want to starve it for fuel. I will check, unless somebody has the info already, on how many cfm the factory pumps deliver. I will get back to you tomorrow, or like I wrote, somebody has done this and has the "trick"
"DUB"
I am just a normal driver and I don't race the car.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
grandmastercorvette,
Let me use this opportunity to pick your brain as well.
My car has a 502 HT crate motor. The PO installed the new motor and a Holley electric fuel pump close to the tank. And of course he removed the return line and there are enough rubber hoses involved. I have been wanting to return the car back to almost stock condition. A few questions.
1) Will a stock fuel pump set up work with a 502 HT crate motor?
2) If not, are there other alternatives that resembles the stock set up?
Let me use this opportunity to pick your brain as well.
My car has a 502 HT crate motor. The PO installed the new motor and a Holley electric fuel pump close to the tank. And of course he removed the return line and there are enough rubber hoses involved. I have been wanting to return the car back to almost stock condition. A few questions.
1) Will a stock fuel pump set up work with a 502 HT crate motor?
2) If not, are there other alternatives that resembles the stock set up?
The 502 HO requires an electric fuel pump because the 502 Gen VI block has no mechanical fuel pump boss.
Melting Slicks
Joined: Dec 2006
Posts: 2,483
Likes: 1
From: Bay Area CA
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
A 502 doesn't have a provision for a mechanical fuel pump, so you'll need to go electric with a regulator.
Also, a SB (383) mechanical pump and a BB pump (454) are not interchangable as was stated above. The actuating arms are different.
And agree. Rubber fuel lines between the pump and carb is dangerous. Right up there with running without an air cleaner.
Lastly be careful with pressure. With carbs, it's easy to overpower the needle and seat, especially in a Q-Jet.
Good luck!
Also, a SB (383) mechanical pump and a BB pump (454) are not interchangable as was stated above. The actuating arms are different.
And agree. Rubber fuel lines between the pump and carb is dangerous. Right up there with running without an air cleaner.
Lastly be careful with pressure. With carbs, it's easy to overpower the needle and seat, especially in a Q-Jet.
Good luck!
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I have a stock mech. fuel pump and i'm able to run with my foot on the floor for extended periods of time without fuel starvation.
Thread Starter
Pro
Joined: Oct 2006
Posts: 542
Likes: 3
From: Vilnius, Lithuania
Sorry, but I keep comming back with additional dumb questions. I would like to re-connect the fuel return line to fuel pump, even though it would not be '68 factory correct set-up. What should I be concerned about? I'm thinking, that's what I should do:
1. Inspect the fuel return line, if it does not leak and whether it is connected to fuel tank (not being cut somewhere in the middle)
2. Re-connect the return line to the fuel pump (as seen in the picture below).
3. Start the engine & check how it works
Or am I missing something?
1. Inspect the fuel return line, if it does not leak and whether it is connected to fuel tank (not being cut somewhere in the middle)
2. Re-connect the return line to the fuel pump (as seen in the picture below).
3. Start the engine & check how it works
Or am I missing something?
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Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Linas, that will work. I'd make sure the 1/4 inch isn't clogged.
Also, it's said above that a stock mechanical fuel pump can keep up with higher HP engines (600 was said to be ok and L-88's were said to be ok) but I disagree.
A typical stock MFP will flow about 30 GPH. Trust me. That won't keep up with built BB.
L-88's did not have a typical stock fuel pump. I believe they had a Carter rebuildable pump that's similar to today's Carter Street pump that flows 80 GPH. Somebody can confirm or correct what pump was used on L-88's and ZL-1's, but it wasn't the same pump used on typical BB's.
Also, it's said above that a stock mechanical fuel pump can keep up with higher HP engines (600 was said to be ok and L-88's were said to be ok) but I disagree.
A typical stock MFP will flow about 30 GPH. Trust me. That won't keep up with built BB.
L-88's did not have a typical stock fuel pump. I believe they had a Carter rebuildable pump that's similar to today's Carter Street pump that flows 80 GPH. Somebody can confirm or correct what pump was used on L-88's and ZL-1's, but it wasn't the same pump used on typical BB's.
Last edited by 73, Dark Blue 454; Jun 18, 2009 at 05:02 PM.
Melting Slicks
Joined: Nov 2001
Posts: 2,659
Likes: 7
From: Katy (Houston) TX
CI 7-8 Veteran
Linas,
Check that return line out real good before trying it. A lot of times there was a very good reason that line was not used. And if it's been sitting there unused for awhile there may be a lot of crud in it or it may have started rusting from the inside if any moisure has made its way in there.
Check that return line out real good before trying it. A lot of times there was a very good reason that line was not used. And if it's been sitting there unused for awhile there may be a lot of crud in it or it may have started rusting from the inside if any moisure has made its way in there.
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
pressurize the old lines with compressed air, say 60psi.
then close a valve off to the line, if it holds the pressure for 10 minutes or so,
you should be good with no leaks. 69VETTE
The lines usually start to leak, and thats why they are not used any longer,
usually no one goes in and dissconnects a perfectly working system.
then close a valve off to the line, if it holds the pressure for 10 minutes or so,
you should be good with no leaks. 69VETTE
The lines usually start to leak, and thats why they are not used any longer,
usually no one goes in and dissconnects a perfectly working system.
Last edited by 69Vett; Jun 18, 2009 at 11:45 AM.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Linas,
Check that return line out real good before trying it. A lot of times there was a very good reason that line was not used. And if it's been sitting there unused for awhile there may be a lot of crud in it or it may have started rusting from the inside if any moisure has made its way in there.
Check that return line out real good before trying it. A lot of times there was a very good reason that line was not used. And if it's been sitting there unused for awhile there may be a lot of crud in it or it may have started rusting from the inside if any moisure has made its way in there.
see, you need that thingamabobby on the side there to connect your return line.
DSCF0001.jpg?t=1245360500
Last edited by PRNDL; Jun 18, 2009 at 05:30 PM.
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
That "thingamabobby" is for vapor return line that comes down the drivers side frame rail. It a one way valve that will close if the car ever rolled over on its roof and prevents the fuel from running out the charcoal canister. So at least I have been told and when I tested it when I have had them out, It appeared to be correct.
"DUB"
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
No but BUBBA does.....all teh time as WE all know!
That "thingamabobby" is for vapor return line that comes down the drivers side frame rail. It a one way valve that will close if the car ever rolled over on its roof and prevents the fuel from running out the charcoal canister. So at least I have been told and when I tested it when I have had them out, It appeared to be correct.
"DUB"
That "thingamabobby" is for vapor return line that comes down the drivers side frame rail. It a one way valve that will close if the car ever rolled over on its roof and prevents the fuel from running out the charcoal canister. So at least I have been told and when I tested it when I have had them out, It appeared to be correct.
"DUB"
WE need more pics of more tanks.
The one I think your talking does has the nipple on the drivers side but has a black plastic fuel separator bolted to the side.
Racer
Joined: Jun 2009
Posts: 302
Likes: 2
From: Milton Delaware
Best Carb for a 350
The car came with pretty new Eldelbrock 600 carb and I was wondering if this the best fuel economy carb for this 350. Seems to get poor gas mileage. Just had it adjusted by certified mech so it would pass inspection. Too much CO2. I've a quardrajet is good on fuel. What do you all think? Not so worried about burning rubber. Want to save $$$ so I can drive it around.
Racer
Joined: Jun 2009
Posts: 302
Likes: 2
From: Milton Delaware
Best Carb for a 350
The car came with pretty new Eldelbrock 600 carb and I was wondering if this the best fuel economy carb for this 350. Seems to get poor gas mileage. Just had it adjusted by certified mech so it would pass inspection. Too much CO2. I've a quardrajet is good on fuel. What do you all think? Not so worried about burning rubber. Want to save $$$ so I can drive it around.
Drifting
Joined: Jul 2007
Posts: 1,889
Likes: 23
From: Kansas
Fuel lines blocked
Grandmastercorvette, Mr. Dub. Hose that I am using (SAE 30R7KX) rated gasoline, are at the tank connections (factory) @ new Bosch electric fuel pump (69404) rated @ 6.9 PSI 25 gal flow, on frame next to gas tank. @ factory fuel filter location, @ steel line from carb, to original 1980 steel line from carb to original 1980 steel line which went from manual fuel pump to carb, from original steel line on frame of 82 vette. The only extra hose is @ the new fuel pump location. Removed original 82 sending unit from tank & installed 80 unit. I do not have any drilling on late model block for manual pump.I have no problem with vapor lock. My Question Is ( do I need the return line Tee'ed into the main line for any reason? or can I leave it capped? ) Thank-you for worrying about me, I Appreciate Gene
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
ok, this is going to require some 3D imagination, but the picture I posted above is of a 1968 corvette gas tank. The nipple is for a fuel return line (not vapor) and I believe it has no valve. The gas just pours into that little nipple. After the tank is properly installed it is in fact on the passenger side. That fuel filler hole you see is the top of the tank but it is installed towards the front of the car. That's why the fuel filler is in the middle of the corvette rear deck.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
with you PRNDL. If you remove the fuel cap and look into the tank with the engine idling, you can see the surface of the fuel is agitated somewhat by the returning fuel. I did this on my '69 back when it was new and was curious why the fuel looked disturbed until I figured out the return line coming from the filter, as shown by 68rdstr in post #34, was dumping fuel back into the tank.