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  #1  
Old Aug 27th, 09, 7:20 PM
c69454 c69454 is offline
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Default Fuel return line size?

I'm finally getting around to installing my racepump and back a few years ago when I got it one of the advantages or so I thought was you didn't need a return line but after reading the site recently it looks like it will vapor lock street cruising if I run it dead headed.

Does anyone think I could install a stock fuel line and use it as a return line? to minimize the headache.

I know for the "best" solution the return line should be the same size as the delivery line but 2 - 1/2 lines seems like a pita to plumb back and forth.

What are some of you guys doing as far as plumbing

Thanks

PS, after doing a lot of reading and searching I see since my pump is soo old there has been internal upgrades and gaskets to help with vapor lock so I called up Howard to see what I needed and even though I bought it in 2006 he said ship it back and he will upgrade it for me... pretty cool
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  #2  
Old Aug 28th, 09, 3:00 PM
c69454 c69454 is offline
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Default Re: Fuel return line size?

I should of asked first but I need to make some progress on this car, after ordering my SS brake line from inline I saw they had a SS 1/2 fuel line and since I was told I need a return line I ordered....

SS 1/2 formed fuel delivery line
SS 3/8 formed return line (I know some say it should match and be 1/2 but Howard says I only need a 1/4 so I went in the middle)

I'm hoping to match the return line up to my sending unit and use that for the return since I have a 1/2 bung welded into the bottom of my tank.

Does anyone see a problem with this? should I cut off the tube on the sending unit that goes into the tank so it's not pushing it under the gas in the tank and let it just drop it on top or does it matter?

I need a good flaring tool and have seen Rigid mentioned alot so I will have to track one down since I will have alot of cutting for a filter, etc.

Let me know if anyone has any better ideas or sees any major problems here as I will be doing it next weekend.

Thanks
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  #3  
Old Aug 28th, 09, 8:38 PM
Motorvation Motorvation is offline
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Default Re: Fuel return line size?

No foam/bubbles with return line below fuel level. I let mine free fall from top of fuel cell with no problems (alky). IMHO, a return line saves the pump diaphram (mechanical) and removes pressure spikes from regulator going on/off. 3/8 has to work, but can you have residual pressure build up?

Steve O.
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  #4  
Old Aug 28th, 09, 8:54 PM
c69454 c69454 is offline
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Default Re: Fuel return line size?

That is what I was wondering.. will there be back pressure like with a full tank of gas and it trying to push the gas out which damages the pump

Might be a good question for Howard... I will fire him an email.


Thanks
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Old Aug 28th, 09, 10:35 PM
Schurkey Schurkey is offline
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Default Re: Fuel return line size?

The big question is: Do you want a VAPOR RETURN style return plumbing; or do you want a full-scale performance-style return regulator?

If all you care about is vapor lock--all you need is a vapor return. And that can be the stock-type 1/4" tubing; because you're bleeding vapor through a small orifice (~.060) into that 1/4" tubing. Fuel vapor goes through the orifice rapidly, but it slows down liquid fuel nicely. This is what GM did on lots of A/C equipped cars. The fuel pump vapor return nipple might have been 1/4"; but there was an internal restriction of about .060.

If you're using a return-style fuel pressure regulator, you need the full-size return plumbing. Maybe even a size larger than the supply plumbing.

So: Are you using a dead-head regulator that you could coax into providing a vapor return; or are you using a bypass/return-style regulator that MUST have full-size return plumbing?
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Old Aug 28th, 09, 11:39 PM
c69454 c69454 is offline
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Default Re: Fuel return line size?

Probably the 2nd one on this list...

http://www.racepumps.com/Regulators-Street.html
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  #7  
Old Aug 29th, 09, 12:14 AM
Schurkey Schurkey is offline
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Default Re: Fuel return line size?

Quote:
Originally Posted by c69454 View Post
Probably the 2nd one on this list...

http://www.racepumps.com/Regulators-Street.html
That's set up for a vapor return, so 1/4" tubing is just fine.
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  #8  
Old Aug 29th, 09, 12:17 AM
c69454 c69454 is offline
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Default Re: Fuel return line size?

But bigger is better right

It will still work with 3/8 right? like I said the other idea was if the racepump doesn't work and I have to go electric I can use the 3/8 for a normal return line on the electric.

Or do you think I have to call and order 1/2 in and back? I thought most return lines are always smaller then the supply on newer cars altho that is EFI I guess so at much higher pressure


Thanks
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  #9  
Old Aug 29th, 09, 11:10 AM
c69454 c69454 is offline
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Default Re: Fuel return line size?

I emailed Howard and he replied this morning.. .fast email response for an older guy.. lol...

He said the regulator is a 1/4 with a #70 Holley jet as a restrictor so I will need to use a 1/4 to 3/8 adapter but it should work and I should still be ok incase I have to got back to an elec pump and use the 3/8 for a return


Thanks
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  #10  
Old Sep 17th, 09, 6:02 PM
c69454 c69454 is offline
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Default Re: Fuel return line size?

Just wanted to say I called Howard today for an update on my pump....

He was hee hawing like he had no idea who I was.. even tho I called and emailed ahead of time... he was just stalling.. lol.. he is like oh yeah the BIG BLOCK... I like that guy...

Anyway he already shipped it back to me after like 2 days... I asked how much I owe him he said nothing.... and I got one of his pump shafts and he just said the bill is in the box.. send in a check when you can... what a guy... and to top it off he send me a NEW pump and regulator with a return line which I didn't have before.

Remember now even those this was never removed from the box it is at least 5 years old... what a guy... hope the pump works half as good as his service.
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