fuel PSI regulator
08-08-2003, 11:19 PM
#1
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fuel PSI regulator
ok this might be a dumb question. But it needs to be answered none the less
454 with a 174 blower and s single 1050dom with a holley mech fuel pump. Do i need a fuel PSI regulator? or can i just go tank to filter to pump to carb (dual feed line)??? I go have a PSI sender on the fuel line rigght on the dual line splitter.
454 with a 174 blower and s single 1050dom with a holley mech fuel pump. Do i need a fuel PSI regulator? or can i just go tank to filter to pump to carb (dual feed line)??? I go have a PSI sender on the fuel line rigght on the dual line splitter.
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08-09-2003, 02:01 PM
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i unfortunatly don't have return line on my fuel tank and i woudl assume puting one in is a major project.
as for the push/pull on the fuel filter ther esems to ab ew afew schools of though on that. IE if you push fuel into it and it somehoe leaks fuel will be sprayed everywhere. but if you pull you just get air in the line. Granted you might pop your engine from the lean condition that follows but at least your boats not on fire.
back to eth psi regulator, Use 12 PSI???
as for the push/pull on the fuel filter ther esems to ab ew afew schools of though on that. IE if you push fuel into it and it somehoe leaks fuel will be sprayed everywhere. but if you pull you just get air in the line. Granted you might pop your engine from the lean condition that follows but at least your boats not on fire.
back to eth psi regulator, Use 12 PSI???
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08-09-2003, 05:29 PM
#3
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You should always draw through a filter unless it is specifically designed to hold pressure. From my own experience I would NEVER push through a filter. No matter what way you would do this if there is a restriction in the fuel system then it is going to lean out draw through or push through.
Now generally speaking you do not need a regulator with a mechanical fuel pump. Holley carbs will be safe with up to 10-PSI on the needle valve. Anymore than that it will begin to force the needle off the seat and flood it out. You can put a regulator on it if you want too and you won't need a return as long as you are using a mechanical fuel pump. However if you ever use an electric pump then you MUST have a return line or the pump won't last.
Roby
Now generally speaking you do not need a regulator with a mechanical fuel pump. Holley carbs will be safe with up to 10-PSI on the needle valve. Anymore than that it will begin to force the needle off the seat and flood it out. You can put a regulator on it if you want too and you won't need a return as long as you are using a mechanical fuel pump. However if you ever use an electric pump then you MUST have a return line or the pump won't last.
Roby
08-09-2003, 10:42 PM
#4
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puder,
You don't HAVE to get another regulator. A drawthru blower (like you have) doesn't require any more fuel line pressure to the carb than if the carb was sitting on top of the manifold.
BUT
A blown motor is WAY more picky about how it tolerates a lean condition. AND it demands a significantly higher volume of fuel to the carb. In many cases, the standard fuel pump simply will not supply the carb with adequate fuel at high rpm. This can cause the mix to lean out over a long pull. ALSO, as fuel FLOW increases through a set of lines and fittings, drag in the lines causes there to be less pressure at the carb than at the fuel pump (assuming the pump is still supplying fuel at its rated psi).
Therefore, it is almost a given that you will add a fuel pressure gauge off your dual feed line and have some brave soul stare at it while you run wide open for 2 solid minutes to make sure it doesn't drop any. Chances are, that it WILL. As the line pressure drops, it changes the float level a little bit which leans the mix out.
Unless you observe full fuel pressure (6 to 7) at wide open for 2 solid minutes, you will end up adding more fuel pump. If you do that, then you will usually end up adding an external regulator. If you add an external regulator, the best place to put it is as close to the carb as possible. External regulators "can" be nonbypass style, but if so then you better make sure that the pump is compatible with a deadhead load (not a positive displacement Aeromotive or Carter). Otherwise you will need to use a bypass style. You can return the fuel back to a tee in the feed line, but the fuel can get hot that way unless you run it thru a cooler.
hope this helps.
You don't HAVE to get another regulator. A drawthru blower (like you have) doesn't require any more fuel line pressure to the carb than if the carb was sitting on top of the manifold.
BUT
A blown motor is WAY more picky about how it tolerates a lean condition. AND it demands a significantly higher volume of fuel to the carb. In many cases, the standard fuel pump simply will not supply the carb with adequate fuel at high rpm. This can cause the mix to lean out over a long pull. ALSO, as fuel FLOW increases through a set of lines and fittings, drag in the lines causes there to be less pressure at the carb than at the fuel pump (assuming the pump is still supplying fuel at its rated psi).
Therefore, it is almost a given that you will add a fuel pressure gauge off your dual feed line and have some brave soul stare at it while you run wide open for 2 solid minutes to make sure it doesn't drop any. Chances are, that it WILL. As the line pressure drops, it changes the float level a little bit which leans the mix out.
Unless you observe full fuel pressure (6 to 7) at wide open for 2 solid minutes, you will end up adding more fuel pump. If you do that, then you will usually end up adding an external regulator. If you add an external regulator, the best place to put it is as close to the carb as possible. External regulators "can" be nonbypass style, but if so then you better make sure that the pump is compatible with a deadhead load (not a positive displacement Aeromotive or Carter). Otherwise you will need to use a bypass style. You can return the fuel back to a tee in the feed line, but the fuel can get hot that way unless you run it thru a cooler.
hope this helps.
08-10-2003, 04:56 PM
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I am also looking into a Fuel Pressure regulator... I am running a mechanical Hi-Volume fuel pump on my SBC. I am confused as to how the install is done. I thought that it was a simple bolt on between the fuel filter and carb? I am a little confused now. What is this about a return line? I really dont' want to have to plumb another line....I just need a basic regulator to limit my pressure to about 5lbs...Suggestions?
BH
BH
08-10-2003, 07:24 PM
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Originally posted by BUDAH
You can do just that with no problem but a return does work better if you can and want to install one ,,just get a good mallory or BGrant regulator and bolt it on ,,,
hope this helps you BH
You can do just that with no problem but a return does work better if you can and want to install one ,,just get a good mallory or BGrant regulator and bolt it on ,,,
hope this helps you BH
BH
08-11-2003, 11:27 AM
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I have B+M174 on my 625 HP 502 and would recommend a Regulator. You do not want to run lean on a blown motor. Would recommend a Mallory regulator and fuel pump over the holley, holley's are known to stick. I run 8lbs of prssure at idle and no less than 5 lbs at WOT. I would also install an in dash Fuel Pressure gauge.
08-11-2003, 12:52 PM
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already have the in dash PSI guage. I 'm thinign i need to order a PSI regulator
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08-11-2003, 01:37 PM
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An electric fuel pump motor will overheat if you do not allow it to pass fuel continuously (return line). A mechanical fuel pump could care less if it is not pumping fuel. The diaphragm simply stays full of fuel and the fuel pump arm free wheels. It doesn't hurt it a bit. Simply installing a fuel pressure regulator between the mechanical fuel pump and the carburetor is fine, 6 or 7 PSI is perfect at idle and 4 or 5 PSI is fine at top rpm.
Dennis Moore
Dennis Moore
