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I'm trying to dial in my carb to get it right so I installed a fuel pressure gauge. Gauge shows around 9 PSI at idle, goes down a little when engine is revved up. So I am thinking of getting this edelbrock fuel pump: https://www.summitracing.com/parts/edl-1721 My question is it only has one inlet. What do I do with the other fuel return line - plug it?
Thanks
Note pictures are from when engine was not running.
The first thing I might note is that I thought that is plenty of fuel pressure for a carb. I thought 5-6 psi was a sweet spot, but maybe I'm thinking wrong. I would not plug the return line.
I have a 1980 with a 383 stroker and my fuel pump requirements should be similar to yours. If you insist on buying a new one, I would purchase this:
Carter M6955 Mechanical Fuel Pump 1970-1981 GM Car 5.0L/5.7L, 38 gph flow rate
The first thing I might note is that I thought that is plenty of fuel pressure for a carb. I thought 5-6 psi was a sweet spot, but maybe I'm thinking wrong. I would not plug the return line.
I have a 1980 with a 383 stroker and my fuel pump requirements should be similar to yours. If you insist on buying a new one, I would purchase this:
Carter M6955 Mechanical Fuel Pump 1970-1981 GM Car 5.0L/5.7L, 38 gph flow rate
Max pressure should be held at or below 6. The needle and seats in the carburetor can become overpressured and flood the engine.
Yes, 6 is what I am after. I'm not using a regulator, I figured regulator was just as expensive as a fuel pump so just get the pump. Plus regulator would be more plumbing in al already crowded location.
That is the exact fuel pump I have now and it is giving me (according to the gauge) 9 psi.
I also have a fuel gauge (Mr Gasket 1563) on my setup and my pressures read very normal the last time I ran it. Could it be that the gauge is reading high and you really don't have an issue ? Does the car run fine ?
It is interesting that from the Carter website, it says the Max psi is 9.0 (Jegs website says 5.5 to 6.5), which is what you are seeing,
so either there is something wrong with the pump, it puts out 5.5 to 6.5 psi, or something is wrong with the gauge. Rent or buy a gauge to verify you are getting the correct reading. You may be chasing a non-existent problem
I also have a fuel gauge (Mr Gasket 1563) on my setup and my pressures read very normal the last time I ran it. Could it be that the gauge is reading high and you really don't have an issue ? Does the car run fine ?
Richard
Who knows about the gauge, it is new and of good quality.
I am trying to fine tune the carb and optimize it and I figured this is the best place to start by checking the fuel pressure. I will take another look at it tonight.
I looked at pressure regulators on Summit and they are expensive! Like around $100 or more. Maybe this is the way to go? Looks like a hassle hooking it up but I'll do it if it works.
Carter website: 9.0 psi max <--- so who do we believe ??
Jegs: 5.5 - 6.5 psi
Summit: 5.5 - 6.5 psi
If you go to the Summit site and read the product reviews for the Carter M6955, you will see several reviews from Corvette owners where they chose to regulate the pressure down for this pump.
Richard
Last edited by lakerider57; Apr 11, 2018 at 04:59 PM.
Reason: adding info
A Holley regulator is about $40 and you already have AN line and fittings.....it would be very cheap and easy to install.
You MUST have 6 or less on an Edelbrock......they are very touchy on this fact.
When they blow the floats and fill the bowl up all the way they bleed through the boosters as the float level is higher than the booster at that point. You may not have problem during spirited driving but it will leak horrible when shut off til the pressure is bled off.
A Holley regulator is about $40 and you already have AN line and fittings.....it would be very cheap and easy to install.
You MUST have 6 or less on an Edelbrock......they are very touchy on this fact.
When they blow the floats and fill the bowl up all the way they bleed through the boosters as the float level is higher than the booster at that point. You may not have problem during spirited driving but it will leak horrible when shut off til the pressure is bled off.
A Holley regulator is about $40 and you already have AN line and fittings.....it would be very cheap and easy to install.
You MUST have 6 or less on an Edelbrock......they are very touchy on this fact.
When they blow the floats and fill the bowl up all the way they bleed through the boosters as the float level is higher than the booster at that point. You may not have problem during spirited driving but it will leak horrible when shut off til the pressure is bled off.
Jebby
This is what I had to do. Set at about 5 psi. I have a Holly pump at 9 psi and when I put on the Edelbrock carb it was too much pressure. Runs fine now.
OK, well I completed some work so I thought I'd update this thread.
After I installed the fuel pressure gauge, I didn't really like the way it looked and I also needed a regulator. So I went back and forth about which way to plumb the fuel system (AN vs hard line) and decided to go hard line (3/8 steel). The AN stuff is cool but expensive and you are limited in some things. I also read Lars' paper on fuel line fabbing and decided to go that way.
Up at the carb I started with an Edelbrock fuel line kit which includes the banjo connection and bent line with filter. This system tucks nice under the choke and looks good. I purchased a Summit regulator and logically that sits right at the 'corner' where the line makes a 90 degree bend. I then installed the gauge between the reg and filter.
Bending the fuel line was cool and came out perfect. I used a 3/16 copper brake line to get a template for the bends and bent the 3/8 tube to match. I was surprised it was just right. I also ordered a 37 degree flaring kit so I could join the tube to the AN fitting at the bottom of the regulator. I actually ended up not using it though and flaring to 45. Lars says that's ok ... lol.
So here are the pics:
3/8 NPT male x 3/8 flare female 90 degree fitting which was buried at the back of the hardware store.
Edelbrock fuel line kit attached to carb (AVS 650)
I aimed the gauge this way because it fits better.
With air cleaner back on
With all this done, I hope to get back to checking the fuel pressure and chasing that down.
OK, well I completed some work so I thought I'd update this thread.
After I installed the fuel pressure gauge, I didn't really like the way it looked and I also needed a regulator. So I went back and forth about which way to plumb the fuel system (AN vs hard line) and decided to go hard line (3/8 steel). The AN stuff is cool but expensive and you are limited in some things. I also read Lars' paper on fuel line fabbing and decided to go that way.
Up at the carb I started with an Edelbrock fuel line kit which includes the banjo connection and bent line with filter. This system tucks nice under the choke and looks good. I purchased a Summit regulator and logically that sits right at the 'corner' where the line makes a 90 degree bend. I then installed the gauge between the reg and filter.
Bending the fuel line was cool and came out perfect. I used a 3/16 copper brake line to get a template for the bends and bent the 3/8 tube to match. I was surprised it was just right. I also ordered a 37 degree flaring kit so I could join the tube to the AN fitting at the bottom of the regulator. I actually ended up not using it though and flaring to 45. Lars says that's ok ...
With all this done, I hope to get back to checking the fuel pressure and chasing that down.
Jim
Nice work! Thanks for updating us with the pictures.
What are the black fittings you used for the steel line that connects it to regulator and the one that connects reg to filter that you have the gauge on?
Fuel pump
