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Old 04-22-2014, 09:13 PM   #1
1965
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Default Re: AN-6 or -8 for My Fuel System (SBF)

I am running a 10 from tank thru a 10 large filter to pump and then 10 filter small filter then 10 to regulator mounted on a fuel log with a return of a 10. used all aeromotive a2000 pump and there regulator and fuel log. expensive but figured it would handle any motor comb I want to run
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Old 04-23-2014, 12:24 AM   #2
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Maybe I`m just cheap & stupid, but a lot of these recommendations seem like overkill to me. First off, the origional poster said he is using a 780 Holley, which has 2 large float bowls, and 2 needle and seat assemblies, so it is not as hard to keep the carb full, compared to a Q Jet.
Both my cars have Holley "Blue" pumps and regulators, and have been reliable and adequate for many years.
My 427 FE Ford bracket car has a 780 Holley and runs 9.9-10.0s at 132MPH with the same blue Holley setup and 1/2" hard line since I started running the car over 25 years ago, and my Stocker 85 Mustang has had the same blue pump and reg, with 3/8" hard line and stock gas tank for 11 years. This setup has been fine even with my bracket engine, which has gone 10.3 @128 MPH with a Holley 650, and was obviously more than adequate for the much slower Stocker engine. I`m not saying that spending over a grand on a fuel system is a bad thing, if you don`t mind spending the $$$$, but at least with a Holley carb, there are cheaper setups that will work
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Old 04-23-2014, 01:44 AM   #3
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Take the jets in the carb + the PVCR and figure the total area.
Then take the sizes of the needle & seats. Figure that area.
The two total areas should be close to equal.
Then take a Blue Holley Regulator apart and measure the size of the hole in it. Then figure the area. But wait to get the actual area you need to subtract the area of the pin from the diaphragm that works through the hole & pushes on the check ball. (that pin is a restriction) The flow of you system should more than match what you are flowing at the carb. Area is not the real way to figure it, but is the easy way & is close enough for our use. If it isn't right it could cause float levels to change and down track performance be affected. BTW check the size of the pump inside, too.
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Old 04-23-2014, 07:49 AM   #4
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Default Re: AN-6 or -8 for My Fuel System (SBF)

I've never seen too much fuel system slow a car down.
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Old 04-23-2014, 10:50 AM   #5
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Quote:
Originally Posted by Chad Rhodes View Post
I've never seen too much fuel system slow a car down.
I have, if I get some time a little later in the day I will explain.
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Old 04-23-2014, 11:52 AM   #6
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Default Re: AN-6 or -8 for My Fuel System (SBF)

also while we are at it depending on the type of material your float is made of you just might not have the float set at the correct level causing improper engine performance due to lack of fuel-- look into it its something that does happen from time to time
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Old 04-23-2014, 01:06 PM   #7
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Current wish list.

-10 braided line
MagnaFuel filter
MagnaFuel Quick Star 275 pump
MagnaFuel regulator
Holley pressure gauge
Summit 15 gal aluminum fuel cell and straps
AN hose cutters and Koul AN installation tool for -10

Total damages: $1,044

The pump maxes out at 18psi which is twice what a carb motor needs. It's rated to feed up to 700 hp and I hope for around 500. It's also been used on the street, so I wouldn't worry about burning it out driving to the strip this year towing a small trailer.

There seem to be two return systems, one from the pump and one from the carb feed. One is a closed pressurized line at the carb and the other is a loop back to the tank. Most big pumps return from the pump. Any preferences here?

Thanks for all the feedback and well thought out PMs.

Dale
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Old 04-23-2014, 01:57 PM   #8
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Ours has -10 from tank to regulator and -8 from there to carb. Using a BG 280 pump it shows 14psi on the high side then goes thru a big body Holley regulator which is set to 6-1/2psi. I have not seen it drop pressure down track as of yet. Recently added a gauge on the cowl to confirm this...who knows if it is really accurate/responsive enough to show tho.
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Old 04-23-2014, 09:19 PM   #9
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Quote:
Originally Posted by Bill Edgeworth View Post
I have, if I get some time a little later in the day I will explain.
I have seen a couple things that I would deem as problems created by oversized fuel systems.
Hot fuel on systems with real big lines. If you are using real big lines on a low horsepower application the flow velocity is quite low. So when you throw a #10 system on a lets say 350hp motor the fuel takes a long time to get from the cell to the carb. Most of that time its spent in a fuel line that is probably routed through areas exposed to a fair amount of heat either radiated from the ground, exhaust or engine compartment. All I can say on this issue is if you insist on putting a system in your car that could support 1000hp make sure it’s well insulated. I should also add putting in way too big a pump generates heat in the fuel.
Another example of better isn’t bigger is a problem a friend faced on his modified car a few years back. He decided to freshen his carbs and afterwards had a huge problem with the car stumbling after the launch. During the freshen on the carbs he figured what the heck he might as well get all the good stuff from Brasswell. He spent big bucks on their bowls and needle and seats. Figured bigger was better. Turned out (and I understand C-25 is especially bad for this problem) as the floats dropped and fuel started to flow after the launch the inrush into the bowl was so great that it causes spill over into the boosters. Not sure if it was foaming or just the flow being so high that it pushed the fuel into the boosters. Moving the floats up or down did not help. He took the big Brasswell needle and seats out and put the smaller stuff back in and the problem went away. Guess the lesson here is don’t use Pro Stock carb parts on a 300 inch motor.
I know in my car running 11 teens in H I used to just run a Holley blue pump with no problems the data recorder showed no fuel pressure or O2 issues. I decided to upgrade to the Magnafuel 300 when the Holley was getting a little noisy and immediately started having problems with the hydraulic shock at start up overpowering the regulator and the Q-Jet. Took a bit of work and a real light regulator spring from Magnafuel for the bypass on the pump to solve the problem.
Adger touched on the subject talking about orifice sizes; there is not much point in having fuel lines 20x the size of the flow orifices in your pump, regulator or needles and seats. The system needs to be big enough to not cause excessive pressure drops but way bigger could possibly cause you some grief.
My .02
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Old 04-23-2014, 09:27 PM   #10
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Default Re: AN-6 or -8 for My Fuel System (SBF)

Quote:
Originally Posted by Bill Edgeworth View Post
I have seen a couple things that I would deem as problems created by oversized fuel systems.
Hot fuel on systems with real big lines. If you are using real big lines on a low horsepower application the flow velocity is quite low. So when you throw a #10 system on a lets say 350hp motor the fuel takes a long time to get from the cell to the carb. Most of that time its spent in a fuel line that is probably routed through areas exposed to a fair amount of heat either radiated from the ground, exhaust or engine compartment. All I can say on this issue is if you insist on putting a system in your car that could support 1000hp make sure it’s well insulated. I should also add putting in way too big a pump generates heat in the fuel.
Another example of better isn’t bigger is a problem a friend faced on his modified car a few years back. He decided to freshen his carbs and afterwards had a huge problem with the car stumbling after the launch. During the freshen on the carbs he figured what the heck he might as well get all the good stuff from Brasswell. He spent big bucks on their bowls and needle and seats. Figured bigger was better. Turned out (and I understand C-25 is especially bad for this problem) as the floats dropped and fuel started to flow after the launch the inrush into the bowl was so great that it causes spill over into the boosters. Not sure if it was foaming or just the flow being so high that it pushed the fuel into the boosters. Moving the floats up or down did not help. He took the big Brasswell needle and seats out and put the smaller stuff back in and the problem went away. Guess the lesson here is don’t use Pro Stock carb parts on a 300 inch motor.
I know in my car running 11 teens in H I used to just run a Holley blue pump with no problems the data recorder showed no fuel pressure or O2 issues. I decided to upgrade to the Magnafuel 300 when the Holley was getting a little noisy and immediately started having problems with the hydraulic shock at start up overpowering the regulator and the Q-Jet. Took a bit of work and a real light regulator spring from Magnafuel for the bypass on the pump to solve the problem.
Adger touched on the subject talking about orifice sizes; there is not much point in having fuel lines 20x the size of the flow orifices in your pump, regulator or needles and seats. The system needs to be big enough to not cause excessive pressure drops but way bigger could possibly cause you some grief.
My .02
Makes a lot of sense. Efficiency is important.

Thanks.

Dale
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