Thank you for all the time and info in your videos Randy, i had a Jeg's liquid filled gauge on my 850 gave me a ton of fits so i got a Mr.Gasket cheap O to see what was going on, old one was at 2 psi but really at 10 psi with new one, so looking for a better one now. Thank again,Scott.
I'll tell ya what Randy, I've been watching your videos all day today. Love them! Your carb explanations make it very easy to understand. I'm trying to dial in my tunnel ram with dual 660's on my 427 and this was extremely helpful.
Super video , and yes sir my fuel pressure is just under 6 lbs . Gotta go and watch your ot h er videos, I'm still fighting my super rich ultra double pumper on my cobra, the more I watch your videos the closer I get to solving my problem. I'm a ga. boy, reckon I should just bring it you guys so I can watch n learn or just get er done and go back to driving.
Great Videos. Thanks for sharing your knowledge. I have a question about fuel pressure and idle mixture setting when using 4150's in a air box with a procharger. Do you run the fuel pressure higher to offset the boost pressure? Do you have a rule for setting idle mixture screws for example say 1/4 turn richer since you don't have access to the idle mixture screws with the additional air at idle with the air box closed? This is a marine application so setting out of gear adds additional variables.
Great video I am running a 500 cc Holly 4412s 2bbl on my 69 Ford f 250 390 c.i it says in the instructions 5_7 psi ? For a 2bbl ? It has a 50 cc accerator pump. I am running a elec fuel pump with the same regulator you had by quick fuel 1_5 psi regulator although the pump is 4_9 psi I ran it in a 5 gallon can it filled that can pretty quick the needle and seat is supposed to stop the fuel right ? I have it set a 3psi that seems plenty for a 2bbl can't see over 4psi on a single bowl , I had thought to get a lower rated pump 2.5 to 4psi since I think the pump is to high for the regulator with the screw all the way out it will.only go as low as 3 psi ... Also I have a hard time getting a fuel pressure gauge to work I had to hold fuel outlet with my finger to block the fuel off to get the gauge to work I ran it at the top of a t fiiting is it because it was running in the bucket and not hooked to the carb ??? I'm a newborn lol ....
how much is the proper fuel pressure psi at idle?...I just added the holley fuel lines with the pressure gauge and it shows 3psi at idle but the engine works perfectly.
three psi is a little low i'm assuming you have a manual fuel pump but if your pressure comes up to 4 to 6 psi racing the engine up and you have good volume you should be ok, don't know if this is a street car or race car , a lot has to do with what you are using it for, if pressure does not rise quickly with engine speed would replace pump, need more information for sure , like engine and carb style and what your doing with it, hope this helps randy
What happens when it’s too much can needle seat get damaged? Was running 7psi turned regulator down put needle and seats back in turned fuel pump on still flooding. Thanks for video
Usually it don't hurt anything , watch my video on flooding , I covered most things that causes flooding , sometimes you run a cross a bad part, I thing the video was next to the last .
hey randy I have a 350 small block with a quick fuel brawler 750 diecast. My question is if I have the car on how do I get the pressure up to 6 PSI? Right now its at 3
I need more information , if you have a mechanical fuel pump or electric pump i take it you have a fuel pressure regulator if so you can adjust the pressure there usually its a stud and lock nut, loosen lock nut and turn stud clockwise slowly and recheck till you reach your desired pressure. If you don't have a pressure regulator then just check your fuel pump out put for a weak stream also check fuel filter for blockage or dirty. Hope this helps.
Hi Randy, I bought a Holley 12-834. It says GPH is 80, and psi is 7.5 and says regulator not needed. I have a 450 hp 383 stroker sbc with a 750 Holley...I bought this pump because its a compact design that I needed to fit in my 55 Chevy 210...whats you thought on this?
Hi Randy, my holley 670 street avenger has a real hard time starting when its cold if you give it more than a pump it doesnt want to start but when you do get it started you need to hold the idle up for a minute to keep it from dying out which it usually will a few times regardless of trying to give it a little gas or just letting it try to idle. I believe it may have something to do with fuel pressure because when i first start it up cold it has 8-9psi but then once warm will drop down to 5-6psi and run great and when warm starts right up with a bump of the key. Any suggestions on the cold start issue and high fuel pressure when cold? Thank you in advance
And just figured i should add that i have the aeromotive fuel pressure gauge that has the little pin to release the pressure when warm to keep the reading consistant but it still isnt. Also the fuel pump is a holley 110gph mechanical pump
Paul I would fix the fuel pressure first should stay the Same hot or cold , I had some problems with the holley pumps , they hate any kind of contamination especially dirt which causes the spring loaded bypass piston to stick at times and make the fuel pressure erratic , then if you still have concerns write me back.
I'm running a Holley 12-834 fuelpump which max is 7.5 psi on my SBC 400 and the fuel pressure bouces between 7psi and 11 psi is there something wrong with the fuelpump I run these fuelpumps all the time with no issues and the car runs and drives GREAT?Thanks
Dickey usually 7.5 psi is questionable, some carbs will handle that some won't, there is a lot of factors including heat and fuel and pivot points and types of float material, I would try lowering fuel pressure to 5.5 to 6.0 psi.
Any pressure regulators with return lines you’d highly recommend? Finding a lot of people putting down big name brands on normal street car regulators but I don’t need a crazy fancy one. All I’ve got is a 10:1 N/A Cammed 350 sbc with a Holley 4150 650 double pump
I dont recommend using a return fuel system on a street car, I've used them on most of my race cars with great results .Fuel didn't creep up stays very consistent, but street use no I would not recommend using a return system to dangerous , fuel leakage on the return side would not effect the engine performance , and could be a very dangerous fire Hazzard. I ran a return fuel system (achohol) on our open wheel modified dirt race car and on our drag cars. But I would never run it on a street. car.
@@holleycarbshowtosadvice40y90 I was looking at switching to a fuel cell in the bed instead of my cab in my 63 C10 and going to braided lines. Wanted the return for safety from flooding bowls and to help circulate fuel so temps stay little lower. Still think it would be dumber to go that route?
You replied to my question in your other video yesterday about my issue with fuel flowing from only one primary booster starting at about 2k rpm. I measured my fuel pressure today and it's 8.5 psi. So at first I was concerned but I know many accomplished racers running the same pump without a regulator. It's a discontinued Carter 172 BBC mechanical race pump. The spec sheet says 8.5 psi and a similar Holley pump is rated at 8 psi. Floats are adjusted without any issues. I'm a little confused because many guys with fast and well setup drag cars are running these pumps.
Well to me that's a lot of fuel pressure John but if you are just strictly drag racing you might get away with it, alot of different fuels and heat will change things, if you are just drag racing sometimes your ok , but I assure you it's not always that way, I normally run 7 psi or less but I run an electric pump . Now that being said, I have much more confidence in a mechanical pump than in an electric pump when it comes to dependability , they both have good and bad things, electric has continual flow were mechanical has to see two full revolutions of the motor to pump once. With me it would matter what I'm doing with it. With most things volume always trumps pressure. Hope this helps.
Can you help Holley isn’t no help. I have a return style regulator and set the pressure at 6.5. I can go drive around for 10-15 minutes and then the pressure is at 3psi. I can reset it at 6 and then it goes to 7+. I put a gauge on the regulator and at the at the fuel log to try to trouble shoot the psi. I have a Holley blue and changed the regulator bc Holley said not to dead head the regulator. I installed a return line and also bought another fuel pump. If I don’t adjust it the pressure at the carb goes to 0 the car doesn’t die but I haven’t had it in the track to see if it starves. Any suggestions or just set it and don’t worry about it?
Brian drive it and when the fuel pressure drops check the fuel volume at the carb if there is very little fuel then start tracing back to the tank. Remove the gas cap to see if its a venting problem, look for any type of restriction or hole in any rubber hose , make sure the fuel pump is mounted correctly , some fuel pumps won't pull gas they have to be gravity fed, I also had a problem similar to yours and it turned out to be dirt in the tank and it was sticking the pressure regulator valve in the electric pump driving the fuel pressure crazy. Hope this helps.
hi Randy, I run a holley 4175 spreadbore on AMC 304 V8 in jeep cj5. Mechanicsl pump, using Mr. Gasket fuel regulator in dead head system. Running 3.5 to 4 psi. Everything is great. Use is off and on road. I did not want any fuel spill over so I set the floats a tad lower. Also used the whistles in bowl vents. A guy on utube said the spreadbore likes only 3.5 psi. No problems yet but rough trails are ok and hill climbs?? Dont know yet. Also I have installed float springs to keep floats stable. Any comments I would like you to give please. Other jeep guys said holley is bad for off road. My 4175 is getting amazing gas milage 18 mpg. The 304 can idle down to 200 rpm and is smooth as silk.
Struggling with my pressure regulator install. Wondering if there is too much pressure for regulator coming in, but Can't find answers. And should I be using thread locker on adjustment nut and screw? It sprang a leak from there after a little driving. t was working for about 10 or 12 miles worth of driving. Ugh!
If it leaking around the adjustment screw when you loosen the nut the diaphragm is ruptured, and probably won't control the pressure and there's no need to put thread locker on the adjustment screw or nut at all. As far as the pressure I would have to know what pump your using. Let me know and maybe we can sort it out. Hope this helps.
@Holley Carbs: How To's & Advice ,40 yrs of exp. I know nothing, so forgive the dumb question's. I basically installed a deadhead regulator (rated for controlling fuel PSI to 4-9 PSI). Inlet without the Deadhead regulator was 10-11 psi (per the in-line gage). Do you think it's also possible Nut wasn't tight enough? I'm referring to the adjustment nut and screw on top of regulator.
I recently swapped a new Holley 850 DP with a 650 DP and I can't get my 383 to run with less than 10 pounds of fuel pressure. I've adjusted the carb up and down to try and lower the fuel pressure and it just won't run. I'll be changing the fuel filter next. I am open to thoughts and ideas
It did but I'm trying to get better gas mileage. I'm trying to put a bog truck back on the street. I did get the 383 to run on 7lbs. After changing the fuel filter. My problem now is I'm getting popping out of one cylinder so Ive got a valve lash problem on the roller rocker or my cam has gone to shit. I want to get rid of the roller rockers and put regular rockers in it. I'm learning as I go and it sucks. Nobody near me knows how to nor wants to work on hot rods.
There is several things that can cause the valve lash to tighten up and cause this popping ,include cam lobe wear on a flat tappet cam or valve seat recession, popping can be caused by a broken valve spring ,there is a long list of things, hope this helps. PS the 650 could have problems too.
I like to use electric high volume pumps at the race track, 6psi to 7psi with return regulator. Not racing I want to see 5 to 6psi , just remember a mechanical pump has to see the crankshaft turn two complete revolutions to pump fuel one time. Electric has steady fuel flow , sometimes you can get away with a stock pump it matters what your doing with the car and the size of the engine.Hope this helps.
Hi Randy. Have you ever known a mechanical fuel pump to over-pressurize under wide open throttle conditions? I have a 383 SBC with a mechanical pump and no regulator. At idle I have 6.5ish psi. No signs of flooding or booster leaking at idle. However, when I go over half throttle and get into the secondaries (Quick Fuel 750 dp) it goes pig rich. 10:1 on an air fuel gauge. No amount of jet changing (10+ sizes) has leaned it out. I’m out of ideas except for maybe it’s a fuel pressure issue? I have swapped out the carb for a new Edelbrock to rule that out and it does the same thing. Also bought a brand new air fuel meter and o2 sensor to rule that out as well. Still no luck!
I have seen stock mechanical fuel pumps pump as high as 13 psi, now the majority of them pumped maybe 8 to10 psi at idle but the pressure would increase with rpms. So you could diffenitely have this problem. I use to hook my inline fuel pressure tester up and monitor the fuel pressure as I raised the engine rpms up, the pressure would increase usually by 3000 rpms the pressure would be way to high ( 10 to 13 psi ). Please let me know if the fuel pump is the problem, if not we'll figure something out.
Ok thanks Randy. Should my first step be adding a regulator with the existing pump? Or will I still get pressure creep with a regulator if the pump is “bad” and gradually increasing pressure with revs?
If you know the pressure is rising with the rpm then I would replace the pump as far as regulators I only like the bypass regulators for strictly drag racing , they don't seem to creep. hope this helps.
You always feed the carbs the same pressure ,if your just cruising 5 to 6 psi. Full race 6 psi 7 max, a good fuel system has to be designed right for the application. Hope this helps.
If fuel is restricted bad enough it can cause what you described , the most common problem is lost power under a load, but a stopped up carburetor will have a lot of the same symptoms, always check fuel pressure and volume first. Remember you can have pressure without fuel, a cracked hose at the fuel tank will deliver air and not fuel. Hope this helps. thanks for watching.
Check your fuel pressure. 5 to 6psi is what you won't. Install a fuel return regulator and that should take care of it. Make sure it is a fuel bypass regulator ,this will require a good quality fuel return line to the tank .
Also, the size of the return is very important. Generally, it should be at least the same size as the feed, if not bigger. If the return is too small, the regulator will have a hard time, well, regulating.
I agree , I've seen alot of fuel systems where they use one size smaller return , I always ran the same size and never had a problem. With alcohol I ran a Barry Grant regulator that was linked to the carburetor linkage that increased fuel pressure as the throttle increased, idled at 4psi ran 12 psi at wot worked perfect.take care.
Hey Randy, I have a 355 small block with a 650 DP that I just swapped into my camaro. It isn't a race motor but a healthy street motor, made 445 hp on the dyno. I have an electric pump and the pressure at idle is at 3psi. This seems a bit low to me but the spark plugs come out looking rich. I have 67 jets in the front and the float bowls are adjusted properly. I haven't been able to drive the car much because it really does not run well at the moment, stutters and not much power. Any help? Thanks.
Bowtie Performance Watch the videos how to adjust your transfer slots by drilling out your primary butterflies with a 1/16 drill bit. Then you can start jetting smaller.
Yes that is not enough fuel pressure i would run 5 to 6 psi i don't know if your running a fuel pressure regulator if so adjust it to higher pressure if not running regulator then check your pump pressure output and check any fuel filters, may have defective pump.hope this helps
There is a several things that effect booster dribble like booster type, float material,how high the float setting, how much velocity in the venturi for instance big throttle plate with small venturi and an annular booster even the heat can factor in, I've seen holleys run 8psi and with out flooding, I've ran 7psi on my race car but I don't recommend any higher. Hope this helps.
@Holley Carbs: How To's & Advice ,40 yrs of exp. interesting... I've had it happen on both my 870 carbs.. float level was the first issue but now seems to be pressure related. When I get it down to 6psi it stops. I have a radical cam with very low vacuum. Wish I could lean it out at idle more but it starts to stumble when I go any leaner then 1 and1/2 turns in on my mixture screws
I just stumbled upon your videos Randy. I love em! I am a carb-rookie and I love how well you explain everything. Thumbs up pal!
Thanks for watching.
Thank you for all the time and info in your videos Randy, i had a Jeg's liquid filled gauge on my 850 gave me a ton of fits so i got a Mr.Gasket cheap O to see what was going on, old one was at 2 psi but really at 10 psi with new one, so looking for a better one now. Thank again,Scott.
Great thinking and thanks for watching.
I'll tell ya what Randy, I've been watching your videos all day today. Love them! Your carb explanations make it very easy to understand. I'm trying to dial in my tunnel ram with dual 660's on my 427 and this was extremely helpful.
Thanks
Randy nice work - I just added you to my library. Look forward to more of your vids. Keep up the great work.
Thank you Mike
Thanks Randy, well explained sir. Glad to know where I should set my "deadhead" regulator at for my street rod 750 cfm Holley! Cheers from Motown!
Thanks my friend.
Super video , and yes sir my fuel pressure is just under 6 lbs . Gotta go and watch your ot h er videos, I'm still fighting my super rich ultra double pumper on my cobra, the more I watch your videos the closer I get to solving my problem. I'm a ga. boy, reckon I should just bring it you guys so I can watch n learn or just get er done and go back to driving.
Good luck, let me know if I can help
Great Videos. Thanks for sharing your knowledge. I have a question about fuel pressure and idle mixture setting when using 4150's in a air box with a procharger.
Do you run the fuel pressure higher to offset the boost pressure? Do you
have a rule for setting idle mixture screws for example say 1/4 turn richer since you
don't have access to the idle mixture screws with the additional air at idle with the air box closed? This is a marine application so setting out of gear adds additional variables.
I'm not the go to person when it comes to boost I'm sorry.
Awesome video
thanks a lot , let me know if I can help randy
Great video I am running a 500 cc Holly 4412s 2bbl on my 69 Ford f 250 390 c.i it says in the instructions 5_7 psi ? For a 2bbl ? It has a 50 cc accerator pump. I am running a elec fuel pump with the same regulator you had by quick fuel 1_5 psi regulator although the pump is 4_9 psi I ran it in a 5 gallon can it filled that can pretty quick the needle and seat is supposed to stop the fuel right ? I have it set a 3psi that seems plenty for a 2bbl can't see over 4psi on a single bowl , I had thought to get a lower rated pump 2.5 to 4psi since I think the pump is to high for the regulator with the screw all the way out it will.only go as low as 3 psi ...
Also I have a hard time getting a fuel pressure gauge to work I had to hold fuel outlet with my finger to block the fuel off to get the gauge to work I ran it at the top of a t fiiting is it because it was running in the bucket and not hooked to the carb ??? I'm a newborn lol ....
Recheck fuel pressure with another guage and if all else is well with the carb should work fine at 5psi. Hope this helps.
Thank you sir for great video helpful 👍
Glad I could help
Love them keep it up
Glad it was helpful.
Very thieral and understanding
Thank you.
how much is the proper fuel pressure psi at idle?...I just added the holley fuel lines with the pressure gauge and it shows 3psi at idle but the engine works perfectly.
three psi is a little low i'm assuming you have a manual fuel pump but if your pressure comes up to 4 to 6 psi racing the engine up and you have good volume you should be ok, don't know if this is a street car or race car , a lot has to do with what you are using it for, if pressure does not rise quickly with engine speed would replace pump, need more information for sure , like engine and carb style and what your doing with it, hope this helps randy
Great video
Thank you
What happens when it’s too much can needle seat get damaged? Was running 7psi turned regulator down put needle and seats back in turned fuel pump on still flooding. Thanks for video
Usually it don't hurt anything , watch my video on flooding , I covered most things that causes flooding , sometimes you run a cross a bad part, I thing the video was next to the last .
Randy. Any videos on air bleeds and adjustments of afr with them?
Yes look through my videos I have some.
hey randy I have a 350 small block with a quick fuel brawler 750 diecast. My question is if I have the car on how do I get the pressure up to 6 PSI? Right now its at 3
Buy a fuel regülatör. You can adjust to any psi.
I need more information , if you have a mechanical fuel pump or electric pump i take it you have a fuel pressure regulator if so you can adjust the pressure there usually its a stud and lock nut, loosen lock nut and turn stud clockwise slowly and recheck till you reach your desired pressure. If you don't have a pressure regulator then just check your fuel pump out put for a weak stream also check fuel filter for blockage or dirty. Hope this helps.
Hi Randy, I bought a Holley 12-834. It says GPH is 80, and psi is 7.5 and says regulator not needed. I have a 450 hp 383 stroker sbc with a 750 Holley...I bought this pump because its a compact design that I needed to fit in my 55 Chevy 210...whats you thought on this?
Bob you might get by with it , I would rather see no more than 6psi on a street car.
Hi Randy, my holley 670 street avenger has a real hard time starting when its cold if you give it more than a pump it doesnt want to start but when you do get it started you need to hold the idle up for a minute to keep it from dying out which it usually will a few times regardless of trying to give it a little gas or just letting it try to idle. I believe it may have something to do with fuel pressure because when i first start it up cold it has 8-9psi but then once warm will drop down to 5-6psi and run great and when warm starts right up with a bump of the key. Any suggestions on the cold start issue and high fuel pressure when cold? Thank you in advance
And just figured i should add that i have the aeromotive fuel pressure gauge that has the little pin to release the pressure when warm to keep the reading consistant but it still isnt. Also the fuel pump is a holley 110gph mechanical pump
Paul I would fix the fuel pressure first should stay the Same hot or cold , I had some problems with the holley pumps , they hate any kind of contamination especially dirt which causes the spring loaded bypass piston to stick at times and make the fuel pressure erratic , then if you still have concerns write me back.
I'm running a Holley 12-834 fuelpump which max is 7.5 psi on my SBC 400 and the fuel pressure bouces between 7psi and 11 psi is there something wrong with the fuelpump I run these fuelpumps all the time with no issues and the car runs and drives GREAT?Thanks
Dickey usually 7.5 psi is questionable, some carbs will handle that some won't, there is a lot of factors including heat and fuel and pivot points and types of float material, I would try lowering fuel pressure to 5.5 to 6.0 psi.
Any pressure regulators with return lines you’d highly recommend? Finding a lot of people putting down big name brands on normal street car regulators but I don’t need a crazy fancy one. All I’ve got is a 10:1 N/A Cammed 350 sbc with a Holley 4150 650 double pump
I dont recommend using a return fuel system on a street car, I've used them on most of my race cars with great results .Fuel didn't creep up stays very consistent, but street use no I would not recommend using a return system to dangerous , fuel leakage on the return side would not effect the engine performance , and could be a very dangerous fire Hazzard. I ran a return fuel system (achohol) on our open wheel modified dirt race car and on our drag cars. But I would never run it on a street. car.
@@holleycarbshowtosadvice40y90 I was looking at switching to a fuel cell in the bed instead of my cab in my 63 C10 and going to braided lines. Wanted the return for safety from flooding bowls and to help circulate fuel so temps stay little lower. Still think it would be dumber to go that route?
You replied to my question in your other video yesterday about my issue with fuel flowing from only one primary booster starting at about 2k rpm. I measured my fuel pressure today and it's 8.5 psi. So at first I was concerned but I know many accomplished racers running the same pump without a regulator. It's a discontinued Carter 172 BBC mechanical race pump. The spec sheet says 8.5 psi and a similar Holley pump is rated at 8 psi. Floats are adjusted without any issues. I'm a little confused because many guys with fast and well setup drag cars are running these pumps.
Well to me that's a lot of fuel pressure John but if you are just strictly drag racing you might get away with it, alot of different fuels and heat will change things, if you are just drag racing sometimes your ok , but I assure you it's not always that way, I normally run 7 psi or less but I run an electric pump . Now that being said, I have much more confidence in a mechanical pump than in an electric pump when it comes to dependability , they both have good and bad things, electric has continual flow were mechanical has to see two full revolutions of the motor to pump once. With me it would matter what I'm doing with it. With most things volume always trumps pressure. Hope this helps.
@@holleycarbshowtosadvice40y90 Yes it does, thank you very much.
Can you help Holley isn’t no help. I have a return style regulator and set the pressure at 6.5. I can go drive around for 10-15 minutes and then the pressure is at 3psi. I can reset it at 6 and then it goes to 7+. I put a gauge on the regulator and at the at the fuel log to try to trouble shoot the psi. I have a Holley blue and changed the regulator bc Holley said not to dead head the regulator. I installed a return line and also bought another fuel pump. If I don’t adjust it the pressure at the carb goes to 0 the car doesn’t die but I haven’t had it in the track to see if it starves. Any suggestions or just set it and don’t worry about it?
Brian drive it and when the fuel pressure drops check the fuel volume at the carb if there is very little fuel then start tracing back to the tank. Remove the gas cap to see if its a venting problem, look for any type of restriction or hole in any rubber hose , make sure the fuel pump is mounted correctly , some fuel pumps won't pull gas they have to be gravity fed, I also had a problem similar to yours and it turned out to be dirt in the tank and it was sticking the pressure regulator valve in the electric pump driving the fuel pressure crazy. Hope this helps.
hi Randy, I run a holley 4175 spreadbore on AMC 304 V8 in jeep cj5. Mechanicsl pump, using Mr. Gasket fuel regulator in dead head system. Running 3.5 to 4 psi. Everything is great. Use is off and on road. I did not want any fuel spill over so I set the floats a tad lower. Also used the whistles in bowl vents. A guy on utube said the spreadbore likes only 3.5 psi. No problems yet but rough trails are ok and hill climbs?? Dont know yet. Also I have installed float springs to keep floats stable. Any comments I would like you to give please. Other jeep guys said holley is bad for off road. My 4175 is getting amazing gas milage 18 mpg. The 304 can idle down to 200 rpm and is smooth as silk.
You know what your doing, good luck.
Struggling with my pressure regulator install. Wondering if there is too much pressure for regulator coming in, but Can't find answers. And should I be using thread locker on adjustment nut and screw? It sprang a leak from there after a little driving. t was working for about 10 or 12 miles worth of driving. Ugh!
If it leaking around the adjustment screw when you loosen the nut the diaphragm is ruptured, and probably won't control the pressure and there's no need to put thread locker on the adjustment screw or nut at all. As far as the pressure I would have to know what pump your using. Let me know and maybe we can sort it out. Hope this helps.
Usually you can buy the diaphragm separately and replace it. Hope this helps
@Holley Carbs: How To's & Advice ,40 yrs of exp.
I know nothing, so forgive the dumb question's. I basically installed a deadhead regulator (rated for controlling fuel PSI to 4-9 PSI). Inlet without the Deadhead regulator was 10-11 psi (per the in-line gage). Do you think it's also possible Nut wasn't tight enough? I'm referring to the adjustment nut and screw on top of regulator.
I have an 80 psi Fuel pump is there a regulator to get that down to 6 to 8 psi?
That is to much fuel pressure get the right fuel pump and be safe
Well explained
Thanks
I recently swapped a new Holley 850 DP with a 650 DP and I can't get my 383 to run with less than 10 pounds of fuel pressure. I've adjusted the carb up and down to try and lower the fuel pressure and it just won't run. I'll be changing the fuel filter next. I am open to thoughts and ideas
Does it run fine with the 850?
It did but I'm trying to get better gas mileage. I'm trying to put a bog truck back on the street. I did get the 383 to run on 7lbs. After changing the fuel filter. My problem now is I'm getting popping out of one cylinder so Ive got a valve lash problem on the roller rocker or my cam has gone to shit. I want to get rid of the roller rockers and put regular rockers in it. I'm learning as I go and it sucks. Nobody near me knows how to nor wants to work on hot rods.
There is several things that can cause the valve lash to tighten up and cause this popping ,include cam lobe wear on a flat tappet cam or valve seat recession, popping can be caused by a broken valve spring ,there is a long list of things, hope this helps. PS the 650 could have problems too.
Is slightly lower fuel pressure than 6 psi okay for the street on a 4150? My delphi mechanical sbc pump specs say it puts out 5 psi?
I like to use electric high volume pumps at the race track, 6psi to 7psi with return regulator. Not racing I want to see 5 to 6psi , just remember a mechanical pump has to see the crankshaft turn two complete revolutions to pump fuel one time. Electric has steady fuel flow , sometimes you can get away with a stock pump it matters what your doing with the car and the size of the engine.Hope this helps.
@@holleycarbshowtosadvice40y90 thank you sir!
Your welcome.
how is the pressure from a original fuel pomp one a 454 bigblok
That varies with who manufactored it most big block pumps usually pump around 5.5 psi
Hi Randy. Have you ever known a mechanical fuel pump to over-pressurize under wide open throttle conditions? I have a 383 SBC with a mechanical pump and no regulator. At idle I have 6.5ish psi. No signs of flooding or booster leaking at idle. However, when I go over half throttle and get into the secondaries (Quick Fuel 750 dp) it goes pig rich. 10:1 on an air fuel gauge. No amount of jet changing (10+ sizes) has leaned it out. I’m out of ideas except for maybe it’s a fuel pressure issue? I have swapped out the carb for a new Edelbrock to rule that out and it does the same thing. Also bought a brand new air fuel meter and o2 sensor to rule that out as well. Still no luck!
I have seen stock mechanical fuel pumps pump as high as 13 psi, now the majority of them pumped maybe 8 to10 psi at idle but the pressure would increase with rpms. So you could diffenitely have this problem. I use to hook my inline fuel pressure tester up and monitor the fuel pressure as I raised the engine rpms up, the pressure would increase usually by 3000 rpms the pressure would be way to high ( 10 to 13 psi ). Please let me know if the fuel pump is the problem, if not we'll figure something out.
Ok thanks Randy. Should my first step be adding a regulator with the existing pump? Or will I still get pressure creep with a regulator if the pump is “bad” and gradually increasing pressure with revs?
If you know the pressure is rising with the rpm then I would replace the pump as far as regulators I only like the bypass regulators for strictly drag racing , they don't seem to creep. hope this helps.
Does the fuel pressure of 6-7psi get divided by 2 if running two carbs
You always feed the carbs the same pressure ,if your just cruising 5 to 6 psi.
Full race 6 psi 7 max, a good fuel system has to be designed right for the application. Hope this helps.
what are the signs of low fuel pressure would having to close the choke to about 3/8" to 1/4" to clean up and run
If fuel is restricted bad enough it can cause what you described , the most common problem is lost power under a load, but a stopped up carburetor will have a lot of the same symptoms, always check fuel pressure and volume first. Remember you can have pressure without fuel, a cracked hose at the fuel tank will deliver air and not fuel. Hope this helps. thanks for watching.
@@holleycarbshowtosadvice40y90 thank you
What is the brand and model number of the 4-way fuel regulator you have there, please?
Aeromotive makes the regulator ,have to get back with you on part#
@@holleycarbshowtosadvice40y90 Thank you so much mate, Cheers :-)
I have one with a stock sending unit and a ac delco fuel pump, into a holly carb and it's flodding out the vent tube
Check your fuel pressure. 5 to 6psi is what you won't. Install a fuel return regulator and that should take care of it. Make sure it is a fuel bypass regulator ,this will require a good quality fuel return line to the tank .
Do I set the pressure with the motor off and pump on?
Yes
Also, the size of the return is very important. Generally, it should be at least the same size as the feed, if not bigger. If the return is too small, the regulator will have a hard time, well, regulating.
I agree , I've seen alot of fuel systems where they use one size smaller return , I always ran the same size and never had a problem. With alcohol I ran a Barry Grant regulator that was linked to the carburetor linkage that increased fuel pressure as the throttle increased, idled at 4psi ran 12 psi at wot worked perfect.take care.
Hey Randy, I have a 355 small block with a 650 DP that I just swapped into my camaro. It isn't a race motor but a healthy street motor, made 445 hp on the dyno. I have an electric pump and the pressure at idle is at 3psi. This seems a bit low to me but the spark plugs come out looking rich. I have 67 jets in the front and the float bowls are adjusted properly. I haven't been able to drive the car much because it really does not run well at the moment, stutters and not much power. Any help? Thanks.
Bowtie Performance Watch the videos how to adjust your transfer slots by drilling out your primary butterflies with a 1/16 drill bit. Then you can start jetting smaller.
Yes that is not enough fuel pressure i would run 5 to 6 psi i don't know if your running a fuel pressure regulator if so adjust it to higher pressure if not running regulator then check your pump pressure output and check any fuel filters, may have defective pump.hope this helps
My 400 block surges like crazy even with the regulator
I need much more information.
How much the tbi engine should have ?
Ahmad Maher Depends , different fuel inj motors vary from 40 -58 psi.
for gm 88-94 tbi you want about 13 lbs at the throttle body.
The old like 1988 chevy truck tbi only needed like 11 psi
👍👍👍👍👍👍👍
Thanks
Hi there by experience fuel pump and old cars carburator will never work together but try it and I will wish you a good luck 🙏
I used them all my life and had good luck.
@@holleycarbshowtosadvice40y90 👍🙏
Did you say 6 or 7 psi???........................
To be safe I would keep my fuel pressure at 5 to 6psi with a all out race car with electric fuel pump 6.5 is good.
Anything over 6psi my holleys dribble out of the boosters real bad.....
There is a several things that effect booster dribble like booster type, float material,how high the float setting, how much velocity in the venturi for instance big throttle plate with small venturi and an annular booster even the heat can factor in, I've seen holleys run 8psi and with out flooding, I've ran 7psi on my race car but I don't recommend any higher. Hope this helps.
@Holley Carbs: How To's & Advice ,40 yrs of exp. interesting... I've had it happen on both my 870 carbs.. float level was the first issue but now seems to be pressure related. When I get it down to 6psi it stops. I have a radical cam with very low vacuum. Wish I could lean it out at idle more but it starts to stumble when I go any leaner then 1 and1/2 turns in on my mixture screws
Reckon you just shaved me about 300$
Thats great. Take care