Hi Folks; I wanted to ask what fuel pressure are you guys running with 1/2" fuel lines throughout the system? The number 7psi comes to mind, but none of the carb manufacturers seem to mention a volumetric flow rate (GPM, or some other unit). I have a suspicion my fuel pressure is too high. Currently set to 6psi. Some background; 1) Problem: I have a BG 850 Demon, that out of the box was pig rich. It wont idle, because the boosters are constantly dripping fuel, as if the engine was at WOT. I don't have much product support available, since BG isn't around anymore. 2) I intend to rebuild the carb, paying close attention to the IFR circuits, and making sure to clear them of any debris. I did have it apart, but nothing was obviously wrong. Everything looked clean. Going to try again and look closer at the IFR, and main wells on the metering block. Before I rebuild it, I just wanted to ask what fuel pressure others are running. The most suggested remedy for this issue to me has been to lower my fuel pressure. I have a Fuel cell in the trunk, and a Holley Black Electric Fuel pump mounted just below the fuel cell. There is an inline prefilter. 1/2" lines carry to fuel to the aeromotive regulator in the engine bay, which feeds 6psi to the carb. There is a gauge on both the regulator (aeromotive) and carburetor inlet (mr gasket) and both register 6psi. The regulator returns the unused flow back to the fuel cell via 1/2" line. Interestingly, the edelbrock 650 that came in my car, doesn't seem to mind the 6psi of pressure. Thoughts?
Demons are very sensitive.to idles speed screw adjusments they really sshould idle off the mixture screws if the blades are open due to to much idle screw its gonna pull fuel ive run 10lbs and never pushed past the seat unless yours just isnt sealing
I agree I think your fuel pressure is to high. Back it down until it quits running over. On my 1050 Dominator I only run 4.0-4.5 psi and I never run out of fuel lines are 1/2". Run the lowest fuel pressure you can to avoid running out of fuel and vapor lock problems. Mike D.
Mike; That's the answer im thinking is right. The part that I don't like, is with the edelbrock slapped on there (no other changes) it has no issues. But I am going to try this anyway. Hugger; The idle mixture screws had zero effect when I was trying to dial it in. Transfer slots were set correctly all around.
I run the CV products billet mechanical fuel pump that Jim Weise sells. I have the Robb Mc 1/2" pick up and -8 push lok hose, and no regulator at all. The pump makes a consistent 8-9 psi. Both my AED 1000, and Q-jet don't seem to have any problem with the pressure.
I run an HP 1000 with a Mallory electric pump and 1/2" lines regulated to 7psi. Never an issue. Just a thought, try replacing your needle and seat if you haven't already. I remember I had a similar problem a few years back and replacing the N&S fixed the issue. Sometimes it's very difficult to see any problem with the naked eye when checking these.
Thanks guys. Was looking to see if anyone is running this kind of pressire with 1/2" lines and some people are. New needle and seats will be put in although the old ones comtrolled the float level perfectly.
Nozzle drip drip drip.....just for kicks try lowering the float 1 or 2 r.c.h 's. Im guessing that Demons have less idle bypass air,
Oooh, good to know Larry. This is the exact setup I'm putting in my car right now. Car's been sitting idle for two years now with the engine rebuilt after melting the #7 piston. Hopefully will be at Norwalk in April.
