Welcome to Our Community

Wanting to join the T-Bucket Forums discussions? Then sign up for a free forum account, today!

Sign Up

Ron Pope Motorsports                                   California Custom Roadsters                                   Spirit Industries                                   Advertise with Us!                                  


Dismiss Notice
Thank you for visiting the T-Bucket Forums! This site was created in 2006, to provide enthusiasts with a place to discuss T-Buckets. Over the years, there have been many imitators, but this is the T-Bucket resource you have been looking to find. We encourage you to register a FREE account and join in on the discussions.

Fuel pressure regulator

Discussion in 'Engines and Drivelines' started by KPoole9008, Sep 6, 2010.

  1. KPoole9008

    KPoole9008
    Expand Collapse
    New Member

    Joined:
    Nov 1, 2009
    Messages:
    59
    Likes Received:
    0
    Gender:
    Male
    I have an electric fuel pump from Summit Racing. It is putting out 7 psi. I have an Edelbrock 750 carb on my 350 Chevy engine. The instructions that came with the carb says the fuel pressure needs to be no more than 6.5 psi. Can I get away with the 7 psi or will I need a pressure regulator ? I have a regulator already that has three fitting openings. One is in the bottom of the regulator [ I assume that is the supply ] and one on the left and one on the right side [I assume one is for the carb and the other is for a return back to the tank ]. If I use the regulator can I block off the return hole ? Thanks
     
  2. Lee_in_KC

    Lee_in_KC
    Expand Collapse
    Active Member

    Joined:
    Mar 15, 2008
    Messages:
    1,179
    Likes Received:
    31
    Gender:
    Male
    Occupation:
    Retired
    I have found those Edelbrock Performers don't like more than about 5 to 5.5 pounds. Above that you will get stalling on hard braking or hard cornering. Edelbrock explained the reason to me is that under hard braking or cornering, the fuel in the bowls moves to one side or to the front and allows the floats to drop, opening the needle valves and flooding the carb. Keeping fuel pressure down reduces the ability of the pump to push the needle valves open when the floats don't have enough fuel under them to overcome the pressure. Does that make sense? Anyway, when I reduced my fuel pressure from 6 to 5, it really helped the stalling, but did not completely eliminate it. I'm going to try raising the floats a little next time I have reason to open up the carbs. My thinking is this will keep the bowls fuller and reducing sloshing. Might just flood it worse... we'll see.

    On your regulator, yes you can plug one of the outlets as long as it is NOT a return-type regulator, which requires a return to function properly. There should be arrows or labels on each of the openings. My Holley regulator has labels and arrows cast in. The bottom opening is "IN" and the two side openings are "OUT." This is a "splitter" type regulator for dual-feed single carbs or two single-feed carb set-ups. The instructions say to plug one "OUT" opening for single-carb, single-inlet applications.
     
  3. ellis8500

    ellis8500
    Expand Collapse
    Supporting Member
    Supporting Member

    Joined:
    Nov 24, 2009
    Messages:
    943
    Likes Received:
    64
    Gender:
    Male
    Occupation:
    Engineer
    I know I'll get a lot of flack for this but..........when I was looking for a car project I started looking at Cobra replicas and read as much as I could about them. What I did find out was that the popular belief among those guys is that Edelbrock carbs do not work well on light weight cars with big engines. Nearly everbody that wrote about their problems getting the ED carb to work well were told to get a Holley carb. Personnally, I do not know if this is true. However, based on some collective knowledge of experience car builders, I decided to stay away from an Edelbrock carb for my 27T. I decided to take a gamble on the new Summit line of carbs. They have the one piece body like the ED carbs but have the internals of the Holleys. Also have site glssses on the bowls and external fuel level adjustments. So far it runs well on the test stand but I haven't run it in the car yet [not fininshed]. I'll let ya all know how it works out when I've got the car running.

    As far as not building the Cobra....too, too expensive. Besides, my wife thinks she'll look just as cool in the 27T.
     
  4. putz

    putz
    Expand Collapse
    Member

    Joined:
    Jun 1, 2008
    Messages:
    3,259
    Likes Received:
    22
    put one of these on my sons truck works great.
    summit

    [​IMG]
     
  5. LarryH

    LarryH
    Expand Collapse
    Member

    Joined:
    Apr 2, 2008
    Messages:
    379
    Likes Received:
    0
    Occupation:
    Retired
    Very smart lady.
     
  6. Gerry

    Gerry
    Expand Collapse
    Member

    Joined:
    Dec 31, 2009
    Messages:
    1,563
    Likes Received:
    13
    Gender:
    Male
    Im sorry but in 2010 I cant believe any maker of carbs can offer that as an excuse for stalling,- HARD cornering or hard braking (heaven forbid I should do either in a T). I may be out of order here but I for one would NOT accept that as an excuse for what seems to be a design fault. I know that float levels can change with acceleration/deceleration but give me a break guys, they cant be serious about this. Its not like they have never been fitted to a car that can pick its butt up and stop on a dime. OR am I missing something here.
    How come the trials bikes can climb mountains, stop with the rear wheel in the air and go from tick over to max rpm in a second. Turn upside down and still keep going!!!
    Gerry
     
  7. ellis8500

    ellis8500
    Expand Collapse
    Supporting Member
    Supporting Member

    Joined:
    Nov 24, 2009
    Messages:
    943
    Likes Received:
    64
    Gender:
    Male
    Occupation:
    Engineer
    From what I recall, it has to do with ED's side mounted fuel bowls. Heavier vehicles do not experience the stopping, accelerating and turning G forces that one can experience in a high powered, light weight car. What they describe is correct. The floats are affected by the G forces in these carbs. Front/rear mount fuel bowl floats do not experience the same effect. Holley carbs have front/rear bowls.
     
  8. GT63

    GT63
    Expand Collapse
    Supporting Member
    Supporting Member

    Joined:
    Oct 26, 2006
    Messages:
    803
    Likes Received:
    14
    Gender:
    Male
    Occupation:
    Lead System Consultant, analysis and programs

    The ED 600 CFM carbs I had on my blown 355 used to do that. If I turned sharp or stopped hard it would stall,as soon as I hit the gas pedal the engine would catch back up. Didn't matter if I had the fuel pressure set at 7, 6, or 5.5.
     
  9. Lee_in_KC

    Lee_in_KC
    Expand Collapse
    Active Member

    Joined:
    Mar 15, 2008
    Messages:
    1,179
    Likes Received:
    31
    Gender:
    Male
    Occupation:
    Retired
    I should clarify... my T only chokes up under VERY hard braking or cornering, well beyond normal driving. I can usually catch it with just a blip of the throttle. I can live with it. Still thinking about EFI, though.
     
  10. Hotrod46

    Hotrod46
    Expand Collapse
    Member

    Joined:
    Aug 22, 2007
    Messages:
    742
    Likes Received:
    66
    I have to agree with Gerry about it being ridiculous that this would be a problem, but I know it is. I've always followed Edelbrocks recommendation and kept my fuel pressure around 5 PSI. No problems and I've ran at least one for over 200,000 miles in a truck. A buddy of mine has never been able to get one to run right without flooding or running rich. I told him to run a regulator, but he said no way, shouldn't need it. I have seen stock replacement Chevy pumps go over 8 PSI. I have to guess that when the original Carter AFB was designed, the fuel pressure was kept low.

    Can't comment on the problems with cornering.

    I've always found it odd that Edelbrock doesn't sell a mechanical or electric fuel pump with pressures set to what they recommend for their own carbs. Of course they also sell air cleaners that won't fit their carbs without an adapter ring too. Strange.

    Mike
     
  11. Wild Mango

    Wild Mango
    Expand Collapse
    Member

    Joined:
    May 15, 2008
    Messages:
    360
    Likes Received:
    27
    Another thing that can cause a "stumble" under high G manouvers is fuel in the bowls sloshing into the bowl vents and riching out the engine. The engine appears to stumble, but in fact its loading up, and a bit of accelerator gets enough air in to burn the rich mix. You can often see the puff of black smoke, and/or smell the raw fuel. Holley (for one) sell vent "whistles" (properly called vent baffles) which fit over the bowl vent and prevent fuel spilling into the vents. With whistles fitted, drop the bowl levels slightly more to keep the floats away from the whistles. Problem solved
     
  12. 2old2fast

    2old2fast
    Expand Collapse
    Active Member

    Joined:
    Mar 25, 2010
    Messages:
    1,171
    Likes Received:
    169
    Gender:
    Male
    Occupation:
    sorta retired
    Regarding this fuel pressure thing , both holley & edelbrock enthusiasts reccomend between 5&6 p.s.i. . I find it difficult to believe this is the case when a quick look through a 72-80 chilton's manual listed most G.M., ford & chrysler V-8 fuel pump pressure at anywhere between 7-9 p.s.i.. comments? dave
     
  13. Screaming Metal

    Screaming Metal
    Expand Collapse
    Active Member

    Joined:
    Mar 12, 2009
    Messages:
    2,523
    Likes Received:
    215
    Occupation:
    Pro Engine Builder, Master Welder
    What Mango said! Also....when hard takeoffs....like drag racing....the fuel will 'climb' the metering plate in the front bowl and slosh in the rear....and in side mounted carbs on tunnelrams and blowers, the float will drop if its a center hung float...both situations contibute to a leaning out, sucking air, or even a flooding condition for a few seconds.

    Also, besides the 'whistle' as Mango suggested, get a piece of rubber fuel line about 6 inches long, cut 2 small notches into this rubber fuel line about 1/2 inch from the center mark of the hose. The notches don't have to be big, just a small something to allow the hose to breath. Now....stick this hose onto your vent tubes on your carb and this will help vent the carb in the corners and in high 'g' manuevers.

    This one will make the old Carrol Shelby folks smile a big one....
     






Advertise with Us! Advertise with Us! Advertise with Us! White Rose Technology Ting Mobile Buy VPN


SSL Certificate