For you carb gurus....where can I look for this problem? Edlebrock 1406, stock 327 SBC engine (I think...mild cam if any) Got it idling fine, 22-23 on vacuum gauge, set idle to best vacuum,around 750-800 RPM. 6psi fuel pressure In Jan I soaked the carb, blew it out, and rebuild kit, set float levels and it seemed fine.It sat for a while,and had to clean some slime out again a month or two later. Idles great, but when I open throttle up to maybe 1500-1800 (haven't looked at a tach) it dribbles fuel out the brass tube nozzle into the booster venturi on the upper left into the drivers side primary throat making it rich,stumble and I have to keep hitting the gas to keep it running. I slide the plates over to watch the metering rods and they seem to be pulled down except when you blip the throttle and move freely & equally depending on vacuum I thought maybe dropping the pressure down to 4 1/2-5 and bought a regulator, but was thinking if the pressure is over riding the float, it would do both primary sides but it's only on the drivers side. Any places for me to look ? I'm going to recheck the float heights and drops and spray some passages,and check the needle/seats The fuel comes out of the brass tube into the ring at the top left....it didn't show the dribbling in this photo
Your fuel pressure is to high. put the regulator on and drop the pressure down a little. If you check on Edelbrock's website you can download the owners manual and it will tell you the exact pressure you need. I think that it is around 4psi.
I'm running two 1406's on mine and am only running 4 pounds of pressure. That is where it seems to run the best, you might try that. If you are getting slime your ethanol fuel is probably turning sour on you. Put some Startron or Marine Stabil in it if you are going to lay it up again. My Son has a T bucket that sits for 6 months at a time or more, and he keeps Startron in it and hasn't had any issues. He is also running two 1406's. Don
Just looked at the instructions for the regulator the speed shop sold me and it says not to use with mech pumps!!! It's a Holley 12-803 I don't know what the difference is,but I'm learning a lot of new crap here.
Yea, I try to run straight fuel,but had to use some E-10 a while back....I added straight so it's about 50/50 now
I don't see that in the Holley instructions, and I don't see what difference it would make. http://www.holley.com/data/Products/Technical/199R7914-3rev5.pdf
Re-read it and it says 12-803BP can't be used with mech....I have the 12-803, I guess that's a different regulator I guess they put instructions in the pkg that cover multiple products
I called Edelbrock and they told me 5.5 psi. I check my GM mechanical pump and it was putting out 8 psi so I used a regulator.
i had a carb that would do that. Drove me crazy. luckily i have a pile of these carbs and just grabbed another and through it on there and now it works great.
I keep reading how everyone claims 4psi for fuel pressure.... Well let me go on record as saying, I run a mechanical pump. between 6 and 7 PSI. I do NOT run any regulator. I have no problems since I did the rebuild.... Prior to, I did have a rich issue, which was a result of the guy before me not knowing what was up when he took the carb apart.... Make sure your High and Low float levels are correct. Each are equally important. And your issue is almost certainly result of poor fuel quality or to high of E10 content... Fill it up with good gas, and a bunch of Sea Foam to clean it out..... Gas dripping out of secondary copper colored tubes is normal when secondaries are opening. And is also not normal at low rpm and will happen if floats aren't right, or crap is in the needle and seat. http://www.edelbrock.com/automotive_new/misc/tech_center/install/1000/1402.pdf exerp....6. Do not use more than 6.5 psi fuel pressure. Excessive fuel pressure may cause flooding. If your fuel pressure is too high, install an adjustable pressure regulator such as Edelbrock #8190.
I would bet your gauge is reading the wrong PSI. Myself and many others have installed a regulator and dropped the pressure down on these Edelbrock carbs and have eliminated flooding issues. I never had dirt or bad gas in the carbs just too much pressure.
Read the original post instead of responding to mine. He states past tense he dropped the pressure already.... Used E-10 .... and cleaned stuff out "slime" since his rebuild..... As I posted, Edlebrocks claim is 6.5. I have no problems after I adjusted High an low float setting, but did prior.... My info is just F.Y.I. per my real hands on experience.
As usual you are giving bad info, So what you are saying is that everyone should run a Edelbrock carb at 6.5 7 PSI just like you do with no issues? We all know how to set float levels on these things but sometimes they just run better at 4 PSI.
That's why I posted the link to edlebrocks tech.... It states 6.5.... Perhaps your issue is with edlebrocks tech then..... I also don't believe your reading the whole thread.... But hey..... Cry away
take 10 guys and ask about a regulator. 5 will say it's a must, 5 will say don't use one. never have i read a post about this that is anything more than guess work.
I added a regualer a few years back. I also have an almost brand new carb that probably only has ablout 300 miles on over the past three years and just this week it wasn't idling good. took it apart and it had dirt in it. looks like the finish is eating away I guess form the ethanal. haven't tried it to see if it will run better yet but hoping it does. maybe dirt is your problem
A fuel dribble can come from a restricted bleed or jet in the carburetor. A restricted idle circuit can cause it too. A flood would seem likely to affect more than 1 nozzle and wouldn't stop the instant airflow (engine) shut off.
I really didn't want to cause any grief here.Thanks for the pointers and I'll try to get to it sometime this week. Hoop, I wondered something like that cause it was only coming from one side. I have lots of ideas to try now....thanks I'll follow up when I find out something
I would check the air bleeds for sure. Now if you think of the fuel pressure blowing the needle off the seat it would not always do it on both sides because once one needle is pushed open it will drop the pressure and not affect the other needle and seat.
The brass tubes shown in the photo?... Are those the discharge nozzles or are they vent tubes? Could there be something out of whack with the bowl venting?
Well it's not guess work and most guys will runaround in circles until they get so frustrated that they think setting themselves on fire is a better idea than checking fuel pressure. Any time there is a drivability problem where fuel is being considered as an issue, one needs to check fuel pressure first. Here's the logic that simply escapes some guys.... The first clue that something is wrong is that you DO NOT have the expected or desired output. In the string of items from that output are a bunch of individual items that are designed to work in unison. At the beginning of that string is a required input ( fuel pressure in this case) that the string was designed around. Unsure of the input, or unwilling to check it, then you really have no idea on what's happening or why it is not happening.
I agree strongly, with a proviso, any problem above idle should get a pressure and "volume" check. Diagnosing is like solving a mystery. You need to eliminate suspects. But when possible by testing, not just replacing. Back to this problem. There is a anti-siphon function built into the main circuit so fuel doesn't siphon out one flow has started. I haven't had time to study this carb yet, but if the air bleed or anti-siphon port that provides this function is clogged fuel will siphon out of that nozzle.
Open up the carb and clean the hell out of it as well as set the floats according to the Edelbrock directions. Fuel pressure regulator set to 4-5 lbs. and no more. I also find that a good fuel filter helps as they seem to be very sensitive to dirt. All from real world experience and not guessing.
And volume depends on the size of the line as well. So a larger line at lower pressure can deliver the same fuel as a smaller line at higher pressure. And you really need to figure out the volume that your engine actually needs.
Mechanical Pump Fuel volume is tested at 0 PSI, no restriction. How To... Use a handheld calculator and plan on .5 lbs/hp-hr. (gasoline). Methanol alcohol requires about 1.0 lbs/hp-hr. Use .7 lbs/hp-hr when planning a gasoline system for nitrous assist. EXAMPLE: You have a 650 hp engine. 650hp x .5 = 325 lbs/hr. (gasoline). Although you need to know how much your fuel weighs, assume for this example that it weighs 6.2 lbs/gal. 325 lbs/hr. ÷ 6.2 = 52.42 gal/hr. Dividing by 60 (minutes per hour) yields .847 gal/min (GPM). Note that this flow number is what your engine needs at the float bowls.
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