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Old 09-07-2013, 03:10 PM   #1
waynes
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Default Dual Carb Fuel Pressure?

I just installed an Edlebrock Regular Dual (Hi-rise) set-up in my 38 coupe. The manifold came from the estate of an old stock car driver who welded a 1/4 inch plate on the bottom. This made a problem with the fuel pump lever not engaging the push rod so I installed a 4-7 lb electic pump and the engine fired right up. Problem is it has a real fast idle and backfires when given more gas. Should I install a pressure regulator or is there some other solution? Thanks.
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Old 09-07-2013, 03:24 PM   #2
ford3
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Default Re: Dual Carb Fuel Pressure?

4 to 7# is to much pressure, 2 to 2 1/2# is all that is needed, any more and you can have a carb flooding problem. is it back firing out carb or tail pipe? most likely a stuck valve causing that
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Old 09-07-2013, 03:43 PM   #3
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Default Re: Dual Carb Fuel Pressure?

Yes about 3x too much. A lower pressure pump would be better along with a suitable 2 to 4 lb regulator , I think Holley blue , but there are others also. Though the round dial type ones are notorious for irregular pressure. So at present you are probably lifting the needle valve off the seat and flooding the carb. Fix the fuel pressure first , the evaluate other issues.
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Old 09-07-2013, 07:18 PM   #4
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Default Re: Dual Carb Fuel Pressure?

Using the right Facet electric pump, there is no need for a pressure regulator as they self regulate to the pressure range you select. One source is Aircraft & Spruce. Thay are made in USA in NY by Purolater. Their tech people can help you pick the right pump for your application. About $35.oo.
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Old 09-07-2013, 07:21 PM   #5
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Default Re: Dual Carb Fuel Pressure?

I have read that 1 backfire is enough to damage you power valve. You may well have other issues as well, but you fuel regulator set for 2 1/2 psi is the first step.
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Old 09-07-2013, 09:08 PM   #6
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Default Re: Dual Carb Fuel Pressure?

2 1/2 to 3 PSI is more than adequate. A stock FP will feed two carbs with out a problem. Get rid of the electric pump and shim the push rod a 1/4". If it backfired through the carbs you may need to replace the PVs.
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Old 09-08-2013, 07:54 AM   #7
waynes
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Default Re: Dual Carb Fuel Pressure?

Thanks to all for input. I ordered a Holley low PSI regulator. I'd like to go back to the mechanical pump and keep electric for backup and intial start up but not sure how to shim the push rod recommended by 41Ford1. Would appreciate input on that.
Thanks again.
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Old 09-08-2013, 01:43 PM   #8
Roger/Sacramento
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Default Re: Dual Carb Fuel Pressure?

I have a new stock mechanical pump which is supposedly around four lbs. pressure and an electrical backup which is rated at four lbs. Don't use a regulator and my three 97's don't leak.
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Old 09-08-2013, 01:45 PM   #9
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Default Re: Dual Carb Fuel Pressure?

rather than shimming, find out how long you want the push rod, right down the length, then braze up the end of rod, file it round so it fits in the push rod hole, then measure rod length, file it to length, ive done that on a lot of my flat head valves when i used a reground cam in my race cars, now i just use chevy valves they are longer
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Old 09-08-2013, 03:10 PM   #10
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Default Re: Dual Carb Fuel Pressure?

Quote:
Originally Posted by waynes View Post
Thanks to all for input. I ordered a Holley low PSI regulator. I'd like to go back to the mechanical pump and keep electric for backup and intial start up but not sure how to shim the push rod recommended by 41Ford1. Would appreciate input on that.
Thanks again.
With the correct length stock pushrod, there is no reason for any shimming.
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Old 09-08-2013, 05:59 PM   #11
Mike in AZ
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Default Re: Dual Carb Fuel Pressure?

might think about pressure gauge to check pressure from regulator.....Mike
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