So much for the Edelbrock fuel pump... |
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OleDutchD
Member Joined: 02-August-2003 Location: Tennessee Status: Offline Points: 151 |
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Posted: 04-June-2006 at 8:46AM |
Been having some questions about my fuel pump from the beginning.
A month ago my carb flooded BIG TIME when I started it one evening. Checked needle/seat assemblies, floats, power valve... nothing. Clean as a whistle and moving freely. Put it all back together and all was fine. What the...? Well, in my haste, I neglected to really watch the fuel pressure gauge. I've noticed some pressure fluctuations from the beginning, but nothing that was really cause for alarm. Well, a week ago while I was riding shotgun in the car I saw the fuel pump throw a 10 psi spike that held on for some time. Fortunately we were on the freeway where the motor speed/load was such (2600 rpm) that it didn't become a great issue. Then it settled back down to 6 psi. After we got off, my wife jazzed the gas (6K in first) pulling away from a stop and I saw the pressure drop to nearly 4 psi!!! Then it became quite clear....time for a new pump! At first I wondered about a clogged filter or pick-up when I saw the pressure drop, but it wasn't consistently repeatable. So, less than 2500 miles on a new Edelbrock Performer mechanical pump (rated at 110 gph @ 5.5 - 6.5 psi), and it appeared to be shot. At a good friends' (McFord) insistence, I relented and stuck a Carter #6904 on it (rated 5.5 - 6.5 psi @ 120 gph). I balked and fought it for a while because it only has 1/4" NPT ports, and being the anal retentive pipefitter that I am, I get all hung up on effective diameters, Cv ratings, pressure drops.... things like that. So to mate it to my existing -8 AN lines (yes, I know.. overkill), I had a toolmaker at work chuck a pair of -8 AN x 1/4" NPT fittings into a lathe and run in a 60 degree countersink bit to open up the ends. The intention being to minimize turbulence at the transition between the effective ID's of the lines and fittings. So anyway, yanked the E'brock pump and did a quick comparison to the new Carter before it went in.... the E'brock pump lever had in excess of 3/4" free play in its' stroke, whereas the Carter has 1/4"! Something amiss there, it would seem. Mounted the new pump, fiddled with connections/lines and turned the key. 6.5+ psi right off the bat and rock solid. Even at operational temp, the pressure hardly changed. The E'brock pump would show a full 1 - 1.5 psi drop when warmed up. Jazzing the gas (in park) produced no fluctuation. Took it for a spin this morning and a 6K blast in 1st w/ a bang to 2nd gear and then twisted to 4K , the pressure just barely dipped to 5 1/2 psi and no fluttering of the needle. Much better! Moral of the story? Hell, I don't know... I'm just a little ol' plumber!! Kevin |
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Just an analog guy stuck in a digital world!
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Psquare75
Admin Group Member of the Stroker Club Joined: 26-November-2005 Location: United States Status: Offline Points: 4591 |
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Sort of related question.. The Ebrock/Carter pumps don't require a regulator? |
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Paul
77 XR7 460/C6/3.00:1 *SOLD* 78 XR7 523/C6/3.5:1 79 F100 460/TKO500/3.25:1 'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500 |
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OleDutchD
Member Joined: 02-August-2003 Location: Tennessee Status: Offline Points: 151 |
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Not these particular pumps, Paul. My understanding is that once you're over 7psi then it's best to step up to a regulator.... according to Jesse @ Bigs. He said you can get away with a little more, but then you start having to crank the float level down to compensate for the added pressure trying to force the needles off their seats, and when you nail it and dump the contents of the bowls in a hurry you run the risk of leaning it out.
For the time being I'm hoping this set-up works for me. As long as I can hold to at least 5.5psi on the big end I think I'm OK. Now I just have to get it on a dyno to see what the A/F ratio looks like through the curve and how the pressure holds up. God help me if I have to jet it up! Kevin PS.. Running 750DP w/ 4-corner idle, 74/81 jetting, 4.5 PV, .033 shooters, .031 idle feeds and the secondary butterflies are cracked to expose about .030" of the idle transfer slot for best idle. |
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Just an analog guy stuck in a digital world!
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JimW
Senior Member Joined: 09-December-2003 Location: USA Status: Offline Points: 602 |
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FWIW, my little Carter electric pump worked for years and years on my 460 with the stock fuel lines..
Jim |
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1976 S&H Gran Torino
460/C6/4.33 13.05@105.6 545/C6/3.56 11.52@117.8 More to come!!!! 463rwhp/495rwtq two tons of fun see it and hear it at: www.torinocobra.com www.st |
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