Anyone know how to setup fuel to two 81's ? I thought I did. Installed a 5-9 PSI inline electric pump with a 1-5 PSI regulator and set it at 3 PSI. When you open the throttle setting still the pressure drops to 1 PSI. How do I get a steady flow of fuel for drag racing?
Like we told you in your other thread, your problem is the type of regulator you are using. those things do not work very well
The original fuel system was gravity feed. Do you really think you need all that much pressure to feed a banger even with two carbs. I don't think much of thst dial type regulator but is it really an issue?
To be efficient you need to rethink all those fittings , to many sizes , 90deg angles , not smooth bore , it all ads up . Do not just Focus on just pressure Volume is needed. If your not familiar with racing There a reason why over years fuel tank moved to front , lets just say a high G force trying to push fuel forward then there is negative G force yada yada. Vent size matters also . With thought you could make a steady Pressurize system with check valve to maintain steady psi & volume,
It might be ignition related. With how the coil is mounted, all of the electricity might be leaking out.
The only thing reliable about that regulator is that it is always inconsistent. Pure Chinese garbage. 3blap.
Get all that JUNK out of your fuel system and run tank-pump-carbs. What pump are you using? Does it have the flow rate you need?
I run 2 81's on gravity works good, 20 years running. If I needed more I would air pressure tank with hand pump.
I have changed to a good regulator, lowered pump so that fuel gravity feeds to pump, reset timing several times, engine still starves and pops under acceleration
Exactly how does it pop under acceleration? Like instantly/in the first car length of kicking her from a standing start? (like would happen with a bad tune, or vacuum leak)? Or after the mill has been winding out for a bit and the carb is running out of fuel? Specific details matter. Not having seen your other posts, I don't know if the car has ever run right or you just did some overhaul/upgrade and the car hates it. -rick
On my banger running a 97 and an 81 (because that is what I had), I run a Holly Mighty Mite 12-425 putting out 1.5-25 psi. The pump is right beside the shut off. I am running one of those regulators like you and a 10lb. pressure gauge. I drag race this car at the dirt drags and the engine easily winds up to 4K without hesitation. I am running an FSI dizzy. Warren
You're right alchemy, I was desperately looking for a 10lb., but ended up running a 15lb. I did see an industrial unit, but wasn't sure if it would work. Sorry for the misinformation. Warren
@alchemy the pressure gauges I use are 0-15 PSI full scale that were for pneumatic control systems... the ones I have are Winters or Marsh and they are really inexpensive and work well...
Run a small header tank in front of the carbs [The weight of the fuel increases with acceleration] The problem could be the pump can't pull [or push] the weight of the fuel from a tank further rearward under G forces There is a reason why g***ers had tanks in the front To test my theory just cannibalize a small tank from a lawn mower Then if it works make a period correct looking header tank from a small fire extinguisher bottle
1-3 lbs max is plenty . Are you sure advance is not causing stump and cough ? As stated throw that style regulator in the trash . You also need a good pump . Constant pressure must be present . When needles are closing head pressure increases on the pump , maybe a return line would help you also . You may not be using as much fuel as the pump is moving at low flow and causing flooding .
I use a Malp***i Fuel Pressure Regulator with my dual 81’s on a Hopped Up Riley. I have a Holly in-line electric pump. Not only does it look good, there are no lags, or pressure drops. I don’t race it, but never had a problem off a stop or under acceleration. The sales picture is few years old so I’m sure the price has changed. I’ll post some pictures of my set up later today.
If you go out on the road and slowly push the pedal down, does it run up to full rpm? If you mash the pedal, does it cut out and pop and not run right while driving? Is the fuel gauge where you can see it while driving? How do you know how to set the regulator if you don't know what the pressure is doing while driving? The round regulators don't always match the pressures marked, have you tried turning one up or one down from the original setting? Fuel pressure between the pump and regulator should always be constant. Fuel pressure between the regulator and carburetors floats will always drop when the floats drop due to fuel usage, doesn't matter what regulator you use. It's no different than holding your thumb over the end of a garden hose, the pressure drops when you remove your thumb. Kink the garden hose and hold your thumb over the end, the pressure is still actual line pressure same as before, remove your thumb, pressure drops same as before, but so does the volume due to the kink. Both ways have the same pressure, but not the same volumes. Does you system have " kinks " preventing enough volume?
These are the only 0-10 PSI fuel pressure gauges I could find when I was looking. I wanted something better and bought the Edelbrock/Russell 0-15 PSI instead. Not a banger but an AV8. I am using a Facet (60104) pump paired with a Malp***i FPR015 return line regulator. Probably overkill but sorts out possible issues suffered by flatties as well as a miriad of other engine/carb combinations. The review: Paired together, the Facet 60104 Posi-Flow Fuel Pump and the Malp***i FPR015 Byp*** Fuel Pressure Regulator create a premium, highly reliable fuel delivery setup for carbureted engines. This combination is a cl***ic motorsport and vintage car upgrade, specifically engineered to solve the common issues of carburetor flooding, vapor lock, and erratic hot-starting. Component Specifications Facet 60104 Posi-Flow Pump Malp***i FPR015 Regulator Application Low-pressure electric lift pump Byp*** regulator with anti-vapor lock Output / Range 1.5 to 4.0 PSI (25 US GPH / 94 LPH) 1.5 to 5.0 PSI adjustment range Port Size 1/8" NPT Female 1/8" NPT Female (Inlet, Outlet, & Return) Special Features Internal check valve, composite quiet casing 1:1 Turbo boost reference port (5mm) Performance Review: Why This Pair Works Seamlessly 1. Total Vapor Lock Prevention The defining benefit of the Malp***i FPR015 is its byp*** (return-to-tank) configuration. Standard dead-head regulators trap fuel in the engine bay when the carburetor float bowls are full, letting it absorb engine heat and boil (vapor lock). By using the FPR015, the Facet 60104 can constantly cycle fresh, cool fuel back to the tank. This completely eliminates hard hot-restarts and fueling stumbles. 2. Rock-Solid Needle & Seat Protection ️ Most cl***ic carburetors (such as Weber, Dellorto, or SU) are highly sensitive to fuel pressure and will flood or weep if pressure exceeds 2.5 to 3.0 PSI. While the Facet 60104 is low pressure (1.5–4.0 PSI), it can spike on a hot day or under sudden throttle closure. The Malp***i regulator tames these spikes perfectly, allowing you to dial in an exact, unwavering 2.5 PSI right at the carb inlet. Crucial Installation Tips for Best Performance The Return Line is Mandatory: Because the FPR015 is a byp*** regulator, you must plumb a dedicated return line back to your fuel tank. You cannot block off the return port. Mounting Positions Matter: Mount the Facet 60104 pump low down, near the fuel tank. Electric pumps are great at pushing fuel but terrible at pulling it. Mount it at a slight upward angle so it self-purges air pocket cavitation. Mount the Malp***i FPR015 regulator in the engine bay, close to the carbs. Always Use a Pre-Filter: Facet solid-state pumps have tight internal tolerances. A tiny piece of tank debris can jam the internal slug. Always fit a 74-micron co**** filter on the inlet side of the pump to protect it. Setting the Pressure: Use a temporary inline mechanical fuel gauge on the regulator's outlet port. Turn the top adjusting screw on the Malp***i clockwise to increase pressure or counter-clockwise to lower it until your target PSI is hit.
Wuga: The part ## is FPR007, is for the regulator. PN FPG001/G is for the matching 0-15 Fuel Pressure gage & regulator sold as a kit. They are specifically designed for low pressure applications. It’s by far the best set up I’ve used and plan to use same one on my other project.
Some times you have to look outside of automotive wish book. Fitting design and types can will affect Pressure , cavitations . Facet brand are good pumps . When diagnosing issues I feel you can not just use , have in this situation OneGauge , need multiple & verify all read Same , calibrate do***ent readings. Working with Low pressure is going to be more critical / sensitive For testing there are gauges that read in 1/8 increments. Mechanical and digital. Me , I would start simple , start @ carb With fewest fittings gravity tank maybe not but work backwards . testing @ each step. & look @ fitting that are cross drilled to say away from , as you move rearward in build of fuel system all those cross drilled fitting , ports add up . Up & down different size ID will cause issues when added up . You might end up with return , byp*** poppet's to cure issue .
Use a Facet 40177. It outputs 1-2 psi so no need for the regulator. I installed mine as shown below and it works well including runs at the drag strip.
The round dial type fuel pressure regulators are reliably unreliable. They self adjust too easily. I love the malp***i but wish they had a bigger diameter fuel flow tube , kinda like a lawn mower size and hope the flow is enough. .
The Jalopy Journal
