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Discussion Starter · #1 ·
Ok, people.

How many of you ran or run a dual fuel regulator setup on a naturally aspirated BBC?

Reason I ask is we ran a single 4 port to 2-1150 dominators. We are using a magnafuel 500gph pump and a magnafuel 4 port regulator. We have 30psi to the regulator and 6.5 to the carbs.

We are putting 2 magnafuel 4 port regulators with a magnafuel fuel log in because we think the single 4 port is not flowing enough fuel. We have .120 needles and seats in the carbs. The engine acts like it is starving at the launch, after the gear change and at about the 1000ft mark. It is a 637 inch 11 degree motor.
 

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6.5 LBS. of pressure to the carbs sounds low , adjust needle and seat for 8.5 (no lower than 7) LBS. that sounds like a good start for your fix . Good luck
 

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Rear mtd fuel cell? I am with 565 here, jack some fuel pressure into it for starters. If it is rear mount cell you might need bigger pump or better to move the cell up front. I can't remember, is the return on the pump? If so you might consider blocking the pump mounted return and return from the fuel log, that'd send all fuel up to the log (assuming it is rear mt fuel cell). If you have front mt fuel cell i'd have the pump tested.
 

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Discussion Starter · #4 ·
Rear mounted cell, pump has been checked a rebuilt. We have used over 6.5 lbs and it caused some aeration in the fuel and the car ran worse.



Rear mtd fuel cell? I am with 565 here, jack some fuel pressure into it for starters. If it is rear mount cell you might need bigger pump or better to move the cell up front. I can't remember, is the return on the pump? If so you might consider blocking the pump mounted return and return from the fuel log, that'd send all fuel up to the log (assuming it is rear mt fuel cell). If you have front mt fuel cell i'd have the pump tested.
 

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Rear mounted cell, pump has been checked a rebuilt. We have used over 6.5 lbs and it caused some aeration in the fuel and the car ran worse.
aeration or/& cavitation? Just a thought, pump position hose size, just maybe? that big engine will need a fair bit of fuel, so maybe you're on the right track too with the log & reg
 

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I run that same pump/reg setup in a pulling truck with a 648" pro stock BBC. We run for a good 15 secounds and I have never had a problem with the engine starving for fuel, so I would look elsewere.
 

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Ok, people.

How many of you ran or run a dual fuel regulator setup on a naturally aspirated BBC?

Reason I ask is we ran a single 4 port to 2-1150 dominators. We are using a magnafuel 500gph pump and a magnafuel 4 port regulator. We have 30psi to the regulator and 6.5 to the carbs.

We are putting 2 magnafuel 4 port regulators with a magnafuel fuel log in because we think the single 4 port is not flowing enough fuel. We have .120 needles and seats in the carbs. The engine acts like it is starving at the launch, after the gear change and at about the 1000ft mark. It is a 637 inch 11 degree motor.
If you go to Barry Grant, he has a fuel can test you can perform. For example, if you have a 7.0 second car you should be able to flow one gallon of fuel under 12 seconds (per float I believe). It's just a test to check your fuel system..
 

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Ok, people.

How many of you ran or run a dual fuel regulator setup on a naturally aspirated BBC?

Reason I ask is we ran a single 4 port to 2-1150 dominators. We are using a magnafuel 500gph pump and a magnafuel 4 port regulator. We have 30psi to the regulator and 6.5 to the carbs.

We are putting 2 magnafuel 4 port regulators with a magnafuel fuel log in because we think the single 4 port is not flowing enough fuel. We have .120 needles and seats in the carbs. The engine acts like it is starving at the launch, after the gear change and at about the 1000ft mark. It is a 637 inch 11 degree motor.
What size fuel lines are you running to the pump, regulator, etc..?
 

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I run that same pump/reg setup in a pulling truck with a 648" pro stock BBC. We run for a good 15 secounds and I have never had a problem with the engine starving for fuel, so I would look elsewere.
x 2!!!

I had a situation where we thought were running out fuel also.. Boat ran worse when fuel pressure was increased. We verified float levels and went down on the main well air bleed from 26 to 22 which, so far, has helped!!!! Just a thought.. My combination is

565" Pontiac 427s with dual 1150s.
 

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u need a bypass regulator and run the fuel pressure at seven the regulator is the restriction in the system i had same problem ,put a bypass regulator in and it flows the same as no regulator at all in system cause it has no restiction to the carbs its wide open in the inside of it
 

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Well i had a simular deal a while back, this may not be your problem but it is something to look at, the car would act like it was starving for fuel after the launch and after gear changes, the plugs would look different from hole to hole, what we finally figured out was the float were not set high enough , when the car would launch the front jets were being uncovered due to the carbs mounted sideways, we set the fuel pressure at 7 and raised the float levels and the problem went away,, pull all of your plugs and start looking there
 

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We run -12 to the pump, -10 to the reg, and -8 to the reg and carbs. Main well bleed? The high speed bleed? We have idles, intermediates, and high speeds.
My bad, high speed.. Couldn't think this morning..
 

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Discussion Starter · #16 ·
We have been through the carbs reset the floats using a .400 drill bit. The plugs are all consistent with one another and we checked them on clean shutoffs after the finish line. We went ahead and plumbed in the dual regulators and set the pressure to 6.5lbs to each carb. The fuel pump does not sound like it is working as hard having to bypass the extra fuel compared to before. I appreciate everyone's input, and will be running the car next weekend. If anyone thinks of anything else feel free to comment.
 

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We have been through the carbs reset the floats using a .400 drill bit. The plugs are all consistent with one another and we checked them on clean shutoffs after the finish line. We went ahead and plumbed in the dual regulators and set the pressure to 6.5lbs to each carb. The fuel pump does not sound like it is working as hard having to bypass the extra fuel compared to before. I appreciate everyone's input, and will be running the car next weekend. If anyone thinks of anything else feel free to comment.
let us know the results ,after you go to the track
 

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Have any of you all even tried running fuel pressure lower than 6? Lower pressure on regulator equals more fuel in bowl. I didn't believe either. I was running lean on big end, talked to quick fuel, he said to just try, i lowered fuel pressure to 5.5, reset bowl level, had to raise level way up. Made a pass, checked recording, to my surprise i was no longer running lean on big end.
 

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I can't really understand this... The only way I can see the fuel pressure changing your fuel level in the bowl is if the fuel is blowing by the needle and seat. if the seat is closed the fuel level in the bowl is "X" wether the pressure against the seat is 5 psi of 8 psi. When the seat is closed the float is essentially against a stop at the top.
 
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