viven44 Posted June 16 Share Posted June 16 My 78 Bronco with the 460 is running rich. I am using a new Edelbrock 1411 (750CFM), with a frame mounted Edelbrock 17301 fuel pump that puts out between 4-7PSI. No return line as I am running the stock tank. Symptoms -- loss in power with sudden throttle application or get up and go... I just don't have the oomph (with Big Blue 2WD as reference using the same Edelbrock 1411). I had assumed this was TC/Transmission related but I'm starting to suspect A/F ratio. -- black soot in tail pipe -- horrendous gas mileage... even for a 460 (this is probably what got me to look into this) -- Idle fuel pressure over 6PSI... but then when warm this number comes down. I know this is gauge related as I've seen gauges with the internal fluid do this when warm (Big Blue 2WD's gauge is at 0 when fully warm ). Questions -- I'm going to install a fuel pressure regulator... Can I set it at 4.5 ~ 5PSI? Big Blue 2WD is at 4.5PSI using the stock 460 hot fuel system and does well. -- Is my assessment correct that I am running rich because the fuel pressure is a bit higher than it needs to be ? I just can't understand why that would as the float would limit the fuel entering the carburetor correct ? I have no leaks or other indications that the pressure is too high. -- Do I need to change the stock metering, etc ? The carburetor is literally brand new with approx. 250 miles on it. Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 16 Share Posted June 16 Do you have two Edelbrocks? If so, swap them? As for pressure, 6 psi is probably too high. What happens is that you set the float level but when the pressure comes up it lifts the needle and tends to raise the fuel level, which makes the AFR a bit richer. But that usually shows up at idle, not WOT. So yes, you can set the regulator at 4.5, which is where I like to run them on an Eddy. It'll be plenty of pressure but not raise the float any. As for the metering, I wouldn't change it until you get the fuel pressure where it should be. Do you know that the secondaries are opening? What happens when they do? Link to comment Share on other sites More sharing options...
viven44 Posted June 16 Author Share Posted June 16 Do you have two Edelbrocks? If so, swap them? As for pressure, 6 psi is probably too high. What happens is that you set the float level but when the pressure comes up it lifts the needle and tends to raise the fuel level, which makes the AFR a bit richer. But that usually shows up at idle, not WOT. So yes, you can set the regulator at 4.5, which is where I like to run them on an Eddy. It'll be plenty of pressure but not raise the float any. As for the metering, I wouldn't change it until you get the fuel pressure where it should be. Do you know that the secondaries are opening? What happens when they do? Good question on the secondaries. The power increase from secondaries opening has been something I have never noticed. In this truck, I can clearly tell when they do as there is immediate boost in power. Before I installed the carb, I could tell (since bottom is visible) also that approx 60 percent throttle the secondaries open. When I rev the truck when parked I can see excess smoke/fuel out the tailpipe. That was my cue to the WOT aspect. I was wondering if excess pressure combined with spikes in fuel pressure during WOT might do some funny stuff. I wish I had a spare carburetor, but I don't. Link to comment Share on other sites More sharing options...
viven44 Posted June 16 Author Share Posted June 16 Good question on the secondaries. The power increase from secondaries opening has been something I have never noticed. In this truck, I can clearly tell when they do as there is immediate boost in power. Before I installed the carb, I could tell (since bottom is visible) also that approx 60 percent throttle the secondaries open. When I rev the truck when parked I can see excess smoke/fuel out the tailpipe. That was my cue to the WOT aspect. I was wondering if excess pressure combined with spikes in fuel pressure during WOT might do some funny stuff. I wish I had a spare carburetor, but I don't. I just climbed up there and verified the secondaries are indeed opening... and they are all the way. Now I did find that for some reason the carburetor had the accelerator pump setting at the very top (Richest). I would have thought the carburetor would have come in the middle spot from the factory! This was a new carb I bought from summit. I set it in the middle now... I feel it is doing better. Maybe a placebo effect :) Will install the "Holley" fuel pressure regulator when it arrives later this week. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted June 16 Share Posted June 16 I just climbed up there and verified the secondaries are indeed opening... and they are all the way. Now I did find that for some reason the carburetor had the accelerator pump setting at the very top (Richest). I would have thought the carburetor would have come in the middle spot from the factory! This was a new carb I bought from summit. I set it in the middle now... I feel it is doing better. Maybe a placebo effect :) Will install the "Holley" fuel pressure regulator when it arrives later this week. I definitely have a 650 AVS in Wilton. I just haven't been there in 9 months.... I'm going to make a valiant attempt at retrieving my tools and will let you know if I still have it. It worked fine on my truck, with minor mods: like a cam, Performer intake and big exhaust. It should be fine in a Bronco (if a little under-tuned, given how heavy my P/U is..) Link to comment Share on other sites More sharing options...
viven44 Posted June 17 Author Share Posted June 17 I definitely have a 650 AVS in Wilton. I just haven't been there in 9 months.... I'm going to make a valiant attempt at retrieving my tools and will let you know if I still have it. It worked fine on my truck, with minor mods: like a cam, Performer intake and big exhaust. It should be fine in a Bronco (if a little under-tuned, given how heavy my P/U is..) Jim, thank you!! but don't worry about that carb.. I think the carb I have is probably just fine, if not.... still under warranty . I'll update after installing the fuel pressure regulator!! Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 17 Share Posted June 17 I just climbed up there and verified the secondaries are indeed opening... and they are all the way. Now I did find that for some reason the carburetor had the accelerator pump setting at the very top (Richest). I would have thought the carburetor would have come in the middle spot from the factory! This was a new carb I bought from summit. I set it in the middle now... I feel it is doing better. Maybe a placebo effect :) Will install the "Holley" fuel pressure regulator when it arrives later this week. If the carb is, for some reason, jetted rich and you hit it with a full accelerator pump shot it'll fall on its face. And any extra fuel pressure will exacerbate the problem. So backing off to the middle is a good idea, and installing the fuel pressure regulator should be next. And you should check the float setting to make sure it isn't too high out of the box. I've seen a lot of poorly-adjusted brand new carbs. Link to comment Share on other sites More sharing options...
viven44 Posted June 17 Author Share Posted June 17 If the carb is, for some reason, jetted rich and you hit it with a full accelerator pump shot it'll fall on its face. And any extra fuel pressure will exacerbate the problem. So backing off to the middle is a good idea, and installing the fuel pressure regulator should be next. And you should check the float setting to make sure it isn't too high out of the box. I've seen a lot of poorly-adjusted brand new carbs. Thanks! Float check requires the air horn to be removed if I'm not mistaken. I have never had to adjust the floats before on an Edelbrock. I'll install the regulator and also keep an eye on the vents to see if I see fuel coming out. I'll call Edelbrock just to be sure on why the accelerator pump setting was not set at the factory defaults. Just in case.... I think on a 302 especially a carb or accelerator pump that is running rich may be obvious but a 460 will drink all the fuel it can get so I'm a bit late here paying attention to this... even now it runs great. Vac is better than 21 inches.... just horrendous gas mileage and a lot of fumes when I rev it while parked Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted June 17 Share Posted June 17 Thanks! Float check requires the air horn to be removed if I'm not mistaken. I have never had to adjust the floats before on an Edelbrock. I'll install the regulator and also keep an eye on the vents to see if I see fuel coming out. I'll call Edelbrock just to be sure on why the accelerator pump setting was not set at the factory defaults. Just in case.... I think on a 302 especially a carb or accelerator pump that is running rich may be obvious but a 460 will drink all the fuel it can get so I'm a bit late here paying attention to this... even now it runs great. Vac is better than 21 inches.... just horrendous gas mileage and a lot of fumes when I rev it while parked Not ALL the fuel a 460 can get! When I first bought the 08457-S that I gave to George for their Ranchero, one of the butterfly screws on the secondary was not tight and hung up the float. Holley demanded their QC was 100%! 🧐 It hydro locked, naturally.... With a mechanical pump, no fuel at all is moving unless the cam is turning. But the higher the R's the more volume you can get. The pump itself has a return line.... Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 17 Share Posted June 17 Not ALL the fuel a 460 can get! When I first bought the 08457-S that I gave to George for their Ranchero, one of the butterfly screws on the secondary was not tight and hung up the float. Holley demanded their QC was 100%! 🧐 It hydro locked, naturally.... With a mechanical pump, no fuel at all is moving unless the cam is turning. But the higher the R's the more volume you can get. The pump itself has a return line.... Amen, brother! When I got Big Blue had bypassed the safeties on the electric fuel pump. Someone turned the key on and hydrolocked the engine. I pulled the drain plug and got 6 quarts of oil and 7 quarts of gas. And each cylinder was FULL as well. But yes, pull the air horn on the Eddy and you can set the float levels. Specs are in this document: https://www.edelbrock.com/media/wysiwyg/documents/carb-owners-manual.pdf Link to comment Share on other sites More sharing options...
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