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09-08-2017, 06:17 AM | #1 |
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Join Date: May 2010
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2 1/2 psi fuel pressure
I've had a few requests for 2 1/2 psi fuel pump springs. To my knowledge
there is not a spring available that fits this criteria. In my opinion many things can effect pump pressure not the least of which is hard to detect wear in the components. My average success rate with achieving 2 1/2 psi the first time with a rebuild is less than 50%. After an unsuccessful test I will install a slightly weaker or stiffer spring depending on the the pressure readings or failing that the lever or base....I never really know. Can't beat real world testing. Charlie ny |
09-08-2017, 06:39 AM | #2 |
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Location: Lehighton Pa
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Re: 2 1/2 psi fuel pressure
Your post makes me wonder if the springs are constant from spring to spring or manufacturer to manufacturer?
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09-08-2017, 01:19 PM | #3 |
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Re: 2 1/2 psi fuel pressure
Phil,
Part of the answer is the number of times the pump has been rebuilt and by whom. Bases and bowls from Holley, AC, B, and off shore bases and bowls get mixed. Then the slotted type of arm vs the bushed type of arm adds to the challenge....it's all good however once the needle settles on 2 1/4 to 2 3/4 psi. Spring consistancy in my experience is vague, different number of coils, slightly different diameters, varying heights....etc etc. Charlie ny |
09-08-2017, 02:55 PM | #4 |
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Location: MN
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Re: 2 1/2 psi fuel pressure
Charlie, what are your thoughts on putting an extra gasket under the pump to lower pressure?
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09-08-2017, 04:20 PM | #5 |
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Re: 2 1/2 psi fuel pressure
I've tried that with limited success, those gaskets are pretty thin. I admit trying this
but it bit me in the behind, I'll spare the details. It's easier in the long run to work within the confines of the pump.......thank heaven for patient customers. Charlie ny |
09-08-2017, 04:59 PM | #6 | |
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Location: Williamsburg, VA
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Re: 2 1/2 psi fuel pressure
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Quote:
Because the pump diaphragm up stroke (pressurizing) is on the down stroke of the push rod, the strength of down spring of the pump lever would theoretically limit pump pressure. That spring also keeps the pump push rod from floating off of the cam at high rpm. I am guessing that the Ford engineers have that spring just high enough to avoid that problem. Interesting physics problem for this winter. I will report back. I recommend keeping the pump at full stroke and using a pressure regulator. Grosse type float valves have worked well for me to over 4 psi. |
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09-08-2017, 05:17 PM | #7 | |
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Location: SLC Utah
Posts: 798
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Re: 2 1/2 psi fuel pressure
Charlie, or anyone else...
I have a pal who does any imaginable spring in any quantity, from medical pacemakers to mine elevator springs and anything in between. He supplies all my choke return springs, accelerator fulcrum springs and throttle speed springs, all heat-treated 302 stainless. Don't laugh, but he has a degree in Spring Engineering. Have a peek at his website: www.springworksutah.com If you'd like a quote, just send me a sample and/or a good description. Everything is CNC and kept in a file, so if I go back for more in 10 years, I get the same thing... Did I mention he did the valve springs for the recent restoration of the Mormon Meteor? Quote:
__________________
RIP Tyler... My Son, Helper & Best Friend. Feb '78 to Father's Day '10. www.97-express.com ~ [email protected] |
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09-08-2017, 05:28 PM | #8 |
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Re: 2 1/2 psi fuel pressure
d,
Good points. The flex in the diaphragm is in the picture. While developing my own diaphragm I tried lots of materials and thicknesses, a single piece of .062 material behaved way different than what I ended up with........which is two pieces of .031 material. The material by the way is military grade viton. Keep us posted on what you come up with this winter. Regulators are great but it's possible to go with full stroke and stay within the comfort range of our little carbs. Charlie ny |
09-08-2017, 06:35 PM | #9 | |
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Location: MN
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Re: 2 1/2 psi fuel pressure
Quote:
Plus I personally prefer the look of just the pump. Thanks Charlie thanks for your response. It's appreciated. |
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09-09-2017, 06:11 AM | #10 |
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Join Date: Feb 2011
Location: Ottawa ON Canada
Posts: 301
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Re: 2 1/2 psi fuel pressure
I know this is a little off topic, but I have been using the Airtek electric pump for several years now, located at the back of my model B. I had the same excessive pressure problems overrunning the carb float. Rather than add a regulator, I put 2 Tee's at the inlet and outlet of the pump and a bypass hose with a very small orifice inserted in the hose to limit the amount of pressure out of the pump. I don't remember the orifice size but was about .02 to .04 if I remember. I used a solder plug and drilled it out till I got the pressure I wanted. Its around 1-2 PSI now, down from the 5 or so.
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09-09-2017, 06:43 AM | #11 |
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Re: 2 1/2 psi fuel pressure
Max,
Thank you for the intro to Spring Works ! Charlie ny |
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