Edelbrock 1721 Fuel Pump conversion HELP
Thread Starter
Instructor
Joined: Apr 2012
Posts: 227
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From: Clarksville Tennessee
Edelbrock 1721 Fuel Pump conversion HELP
I am replacing my stock mechanical fuel pump with an edelbrock 1721 mechanical pump. The problem is with the fuel lines. The old/current setup has 2 lines from the tank to the bowl and one going to the carburetor. The 1721 has one in and one out. What needs to be done? Has anyone else installed/converted a fuel pump this way before. I am very timid when it comes to fuel work so I wanna do it right and safe. 1973 350 SBC.
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
"Generic" aftermarket pumps don't have provisions for the return line. If you want to maintain the return line system to avoid vapor lock issues on your car, you have to put a splitter in the fuel output line with a restrictor orifice for the return. If you don't, you'll risk serious vapor lock issues at the most inopportune time. Unless you're running well over 500hp, send that non-return pump back and install the correct stock pump to keep the system operating with the least amount of custom fabrication work: there's a really good reason why GM spent a bunch of money installing return systems in these cars.
Your other option is to use the '69 GM fuel filter with the return feature on it: You can see the photo in this post with the return line coming out of the fuel filter mounted in front of the carb. If you do this, just make sure you remove the in-carb filter so you don't run dual filters:
http://forums.corvetteforum.com/c3-t...7029207-a.html
Lars
Your other option is to use the '69 GM fuel filter with the return feature on it: You can see the photo in this post with the return line coming out of the fuel filter mounted in front of the carb. If you do this, just make sure you remove the in-carb filter so you don't run dual filters:
http://forums.corvetteforum.com/c3-t...7029207-a.html
Lars
Last edited by lars; Aug 18, 2012 at 10:45 AM.
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
Here is additional info you might want to get familiar with regarding vapor lock and fuel return lines:
http://forums.corvetteforum.com/c3-t...turn-line.html
Also see my posts and photos in the following topics:
http://forums.corvetteforum.com/c3-t...k-in-a-c3.html
(see my post #20)
http://forums.corvetteforum.com/c3-t...d-by-lars.html
Lars
http://forums.corvetteforum.com/c3-t...turn-line.html
Also see my posts and photos in the following topics:
http://forums.corvetteforum.com/c3-t...k-in-a-c3.html
(see my post #20)
http://forums.corvetteforum.com/c3-t...d-by-lars.html
Lars
Last edited by lars; Aug 18, 2012 at 01:29 PM.
Burning Brakes
Joined: Dec 2011
Posts: 844
Likes: 6
From: Fort Wayne, IN
"Generic" aftermarket pumps don't have provisions for the return line. If you want to maintain the return line system to avoid vapor lock issues on your car, you have to put a splitter in the fuel output line with a restrictor orifice for the return. If you don't, you'll risk serious vapor lock issues at the most inopportune time. Unless you're running well over 500hp, send that non-return pump back and install the correct stock pump to keep the system operating with the least amount of custom fabrication work: there's a really good reason why GM spent a bunch of money installing return systems in these cars.
Could you do a similar setup with an Edelbrock carb using a banjo fitting (at the carb fuel inlet) attached to a "T" fitting with a splitter with restrictor orifice then plumb the inlet and return lines the same way you showed? I also have the Edelbrock 1721 pump and would like to fix this little problem before I drop the engine in my car.
I'm looking at doing my own fuel line setup and would like your input.
I have a drop base air cleaner and would like to keep it, so I think the banjo fitting with "T" fitting may be the best way to do it.
Instructor
Joined: Dec 2008
Posts: 103
Likes: 0
From: w. jordan utah
pump
if you run a regulator with return line provision and a gauge it should work. also to run and edelbrock you will need to get the bottom line adapter as the stock position won't work , non liquid filled gauge as lars stated
Last edited by surfertom; Aug 19, 2012 at 10:01 AM. Reason: extra info
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Burning Brakes
Joined: Dec 2011
Posts: 844
Likes: 6
From: Fort Wayne, IN
can you or anyone recommend a good regulator with return? I have seen them priced anywhere between $35 to $185.....not sure how much better one is over another.
where would you recommend plumbing the gauge into the system? After the inline filter (as in the pics) or after the regulator?
where would you recommend plumbing the gauge into the system? After the inline filter (as in the pics) or after the regulator?
Burning Brakes
Joined: Oct 2008
Posts: 1,037
Likes: 14
From: Mobile Alabama
can you or anyone recommend a good regulator with return? I have seen them priced anywhere between $35 to $185.....not sure how much better one is over another.
where would you recommend plumbing the gauge into the system? After the inline filter (as in the pics) or after the regulator?
where would you recommend plumbing the gauge into the system? After the inline filter (as in the pics) or after the regulator?
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
can you or anyone recommend a good regulator with return? I have seen them priced anywhere between $35 to $185.....not sure how much better one is over another.
where would you recommend plumbing the gauge into the system? After the inline filter (as in the pics) or after the regulator?
where would you recommend plumbing the gauge into the system? After the inline filter (as in the pics) or after the regulator?
Install the fuel gauge as close to the carb inlet as possible so it's reading and displaying actual pressure available at the carb inlet. If you install the gauge after the regulator, you'll be in the return line, and the gauge will read -0-.
Burning Brakes
Joined: Dec 2011
Posts: 844
Likes: 6
From: Fort Wayne, IN
I pieced it together using these parts so far.....
Everything is -6 size (from Russell, Mr Gasket, or Edelbrock):
(amount) description - part number
----------------------------------------
(4) Hose Straight end - 610020
(2) 90degree swivel hose end - 613160
(2) -6 flare x 3/8" NPT adapter (for the fuel pump) - 660460
(1) Female straight swivel coupler - 640000
(1) AN Flare Tee - 661020
(1) Flare pressure union adapter (for fuel pressure gauge) - 670000
(1) Edelbrock banjo fitting - 8089
(1) 3" Fuel filter - 650130
(1) Mr Gasket Fuel Pressure Gauge (non-liquid filled) - 1561
(1) 6' prepackaged ProFlex hose - 632060
Like I said, I still need to get my regulator, then I can finish. I'll update here as I do so. Hope this helps
Everything is -6 size (from Russell, Mr Gasket, or Edelbrock):
(amount) description - part number
----------------------------------------
(4) Hose Straight end - 610020
(2) 90degree swivel hose end - 613160
(2) -6 flare x 3/8" NPT adapter (for the fuel pump) - 660460
(1) Female straight swivel coupler - 640000
(1) AN Flare Tee - 661020
(1) Flare pressure union adapter (for fuel pressure gauge) - 670000
(1) Edelbrock banjo fitting - 8089
(1) 3" Fuel filter - 650130
(1) Mr Gasket Fuel Pressure Gauge (non-liquid filled) - 1561
(1) 6' prepackaged ProFlex hose - 632060
Like I said, I still need to get my regulator, then I can finish. I'll update here as I do so. Hope this helps
Instructor
Joined: Dec 2008
Posts: 103
Likes: 0
From: w. jordan utah
fuel pump
looks great , i am planniing a simmilar pump and line install. i will be running a 700 holley duel feed double pump mech secondarys. i think i will mount my reg closer to the pump with a modified smog pump bracket. so i can run a much shorter line to the return. have a holley reg w/return. only problem i can see from your pic is line from tank to pump looks like it will be way to close to the frame rail , which is why they make a bottom plate to move both in and out to carb lines from the side of the pump.
Burning Brakes
Joined: Dec 2011
Posts: 844
Likes: 6
From: Fort Wayne, IN
That was the same angle I had the pump on the motor I had on the car, it had JUST enough clearance with the frame rail to where it didn't rub at all. I used a bare hose, but I think I will go with the braided steel this time around.
Lars, is there a quick easy way to adjust the amount of fuel that's returned on the Mallory, and how much do I back the little "plunger thing" out? Also, do I keep the vacuum comp port plugged?
Once I get my last military paycheck, I will finish and get some pics up of the installation.
Lars, is there a quick easy way to adjust the amount of fuel that's returned on the Mallory, and how much do I back the little "plunger thing" out? Also, do I keep the vacuum comp port plugged?
Once I get my last military paycheck, I will finish and get some pics up of the installation.