I bet if we made a video tour of the exploded view of a Honda B16 you wouldn't think it was too boring... Excitement is subject to the eye of the beholder.
Accelerator pump needs to be tuned. You can do it by getting the Accelerator pump cam tuning kit and then find a cam that works well for your engine. You may also need to to to a larger accelerator pump discharge nozzle (squirter) to get enough gas to shoot in during the flat spot on initial "pedal mash". Complete tuning for that system is covered in detail in our Holley DVD. It's over 2 hours long...
@93Patriot The type of rubber that is used for the needle and seat assembly is a material called Viton. They are designed to seal well for a period of time, but when they reach their end-of-life span, it is normal practice to just replace the needle and seat. There will be no visible wear or clogging that needs to be cleared. It's just the nature of the standard Holley service schedule to replace the needle and seat when they harden. The problem comes from non-use of the engine over time...
Holley Carbs are one of the most popular carburetors for enthusiasts who like to build power and tune their higher horsepower large displacement engines. If your engine has another brand of carburetor you still may be able to use the tuning info from our Holley DVD. You would just need to locate your Idle Mixture screws, idle speep screws and identify the power enrichment circuit for your Bosch carb. Sometimes there is are separate jetting systems for part throttle and wide open as well.
@93Patriot Sounds like the needle and seat assembly needs to be replaced, not just cleaned. It's a standard procedure for any Holley carb as a regular service overhaul. The needle and seat is included with many of the complete rebuild kits as well. Just start by getting a new pair of needle and seat assemblies and replace the one in each bowl. re-set the bowl level and your described problem should be solved. Then you can think about the rest of tuning. Our Holley DVD can help if you like...
@marcelomeazzini That's why we produced a 3 1/2 hour in partnership with Holley. They used to include the DVD in every box with new carbs. You can get the full DVD from our BoxWrench site, but also search here at RUclips for other BoxWrench/Holley carb tuning clips. Everything you'd need to know for tuning a Holly or most carbs is in our videos.
@3MAN09 Double Pumper carbs are most useful for use in higher horsepower engines with large camshaft profiles and/or manual transmissions. They have four idle screws (one for each carb barrel) and also have dual accelerator pump systems (squirters) so you can more effectively tune the acceleration fuel demand curve for the higher HP types of engines. They are most effective at eliminating 'flat' spots in the acceleration curve at the point where the secondary throttle plates open.
@adamslurch71 You would definitely need to have a larger displacement engine to even take advantage of a Holley Double Pumper. The best way to determine if you've engine specifications are large enough to take advantage of the extra fuel delivery from a double pumper is to use the "Carburetor Calculator" at the Holley website. You answer some questions about your engine, RPM range and accessories, and it will guide you to the proper CFM size rating for your engine.
Seems like it may be a good set up for you. Only thing is the secondaries of the carb. With a manual transmission, you would possibly benefit from mechanical secondaries if your carb currently has vacuum secondaries. Not a requirement though, just make sure to get your carb tuned properly with the help of a vacuum gauge and the proper jetting and idle settings.
Which port are you connecting the distributor vacuum line to? It should be the one that exits the passenger side of the primary metering block...not any of the ports on the base of the carb.
That may have been a widely spread opinion years ago but people that don't like Holley carbs usually don't know how to tune them. If you feel a "Flat Spot" in a Holley carb, it's definitely out of tune. That's why we made these videos. There's nothing like them out there, definitely not from Edelbrock or Weber. Every Holley carb comes with the DVD and using it will give you more knowledge of their carbs compared to any other brand out there.
At :21 seconds into this clip, the woman describes what "double pumper" means. It just describes the fact that there are two accelerator pumps, one one the primary fuel bowl and one on the rear fuel bowl. Two accelerator pumps also means there are two discharge nozzles. The discharge nozzles (squirters) are solely responsible for making sure that enough fuel in introduced at the critical "lag" moment when the gas pedal is pressed. Makes for better throttle response in a "Double Pumper"
I have a modified 350 and it has a Holley 700DP on it. We've been having trouble with it constantly loading up and flooding out. We have taken the carb apart, cleaned it, and frequently adjust the floats but it keeps flooding after running the car for a few trips. Unfortunatley it has come to the point that if we can not resolve the problem, the Holley will be coming off and being replaced with a Carter. Any ideas on what may be the problem?
@93Patriot Give the new needle and seat assemblies a try and let us know what happens... there will be a need to be a round of tuning that you go into when you have new seat assemblies, but you should hopefully solve the flooding issue. Keep us posted.
Does that mean that you did a comparison between a Holley and the Q-Jet? Did you actually try to tune a Holley before working with the Rochester? If you followed the instructions in our Holley DVD, you'd have any Holley carb running pretty incredibly well... We've had the opposite experience when comparing a tuned Holley to a tuned Q-Jet, we preferred the Holley every time.
Always wondered about double pumpers. Two fuel bowls. So do you have to run a second line from front bowl or does fuel get to second bowl internally somehow. Im new to double pumpers. Never had one.
Well I told my father who is much more of a mechanic then I am do to me only being 17 about what you suggested but he claims he already took it all apart, checked the needle and that it was fine. Is it possible that the damage is not visiable? Unfortunatley he already has a dislike for Holleys so it's becoming quite difficult for me to convince him to retry stuff such as replacing the needle which he feels isn't broken.
too much to learn.haha..thats why i had my mechanic tune my 650 double pumper..n really loved my carb setup,really liked the holley,but i love the way quick fuel and proform carbs look...so ill be gettin myself one of those.
@BoxWrench Hello I'm running a holley 650 DP on a 1.3L rotary engine. I know it's abit big a 500 would be more what I need for my set up. The engine will idle fine with the choke on but as soon as I take it off the carb leans out, engine high revs and its sputters till it dies. Anyone know what my problem could be? I'm leaning on a air leak. It's getting fuel fine but as soon as that choke is let off game over.
Maybe someone can help with this. 351 cleveland, holley carb. Driving slowly 2nd gear, mash the gas, dead spot and then wooosh. Why does it go dead for a second? Any advice?
mechanical only means the secondaries are open mechanically not with engine vacuum. You can run vac dist and canisters with mechanical carbs. Note mechanical has pros along with cons as compared to vacuum secondary carbs
check your fuel line for a crimp. i was wondering why mine would bog when i reved it, the fucking motor pinched its own fuel line from rocking when under a load. crazy crazy shit. i had it checked by a GM dealership and they said it was a bad wire that can not be located inside the wiring harness
long time ago i modifid rochester for racing that worked muche beter on 350 chevy for drag and street racing i did not beleve it will but it was one of the best things i ever done .
i would keep the 650. A bigger carb would only help you if you had a larger ci small block 383 or 400 or rpm aboove 6500. Putting a bigger carb will most liklely slow you down, foul plugs, bog off idel etc.. I had good luck with a edel 600 cfm on a 350 street motor. I put a 750 on my 406 small block but it had 11.5 cr and a .555 solid lifer cam rpms were 3-6500.
ur damn right, i hate fuel injected i have a 85 camaro with a tuned port 5.7 and i hate it, i mean its fast and all but i have nothing but problems with it
for small block chevy Q-jet workes allmost all the time beter ,i try tune holley it was fine but not very sharp some time you get flat spots in US you can have jet kits to fine tune it power valves but Q-jet is more responsive with small block and very important thing if you go street racing then Q-jet is realy shining.
@93Patriot Unless your dad is using the carb on a race application engine, toss that POS Holley in the trash & snag a good ol' Carter/Edelbrock AVS. much easier to tune & they won't give you the problems you'll continue to encounter with the Holley carbs.
Jay Malinowski Please when will be possible buy your fantastic DVD? I built my 1° engine following your instruction! Please fix the website !!! PLEASEEEEE
I am just pointing out that hollies have a bad reputation for flatspots, thats why they have to give so much info with their carbs. Why do u think the ford GT40 used a bank of webers and not holley? holley is good for pouring fuel into big engines with so much torque that flat spots do not matter as much, but for quality, accuracy etc webber is far better. Bizare that u would use insults to convey ur opinion, r u one of those wierdos that falls in love with objects? like men who fuck cars?
I bet if we made a video tour of the exploded view of a Honda B16 you wouldn't think it was too boring...
Excitement is subject to the eye of the beholder.
Accelerator pump needs to be tuned.
You can do it by getting the Accelerator pump cam tuning kit and then find a cam that works well for your engine. You may also need to to to a larger accelerator pump discharge nozzle (squirter) to get enough gas to shoot in during the flat spot on initial "pedal mash".
Complete tuning for that system is covered in detail in our Holley DVD. It's over 2 hours long...
@93Patriot The type of rubber that is used for the needle and seat assembly is a material called Viton. They are designed to seal well for a period of time, but when they reach their end-of-life span, it is normal practice to just replace the needle and seat.
There will be no visible wear or clogging that needs to be cleared. It's just the nature of the standard Holley service schedule to replace the needle and seat when they harden.
The problem comes from non-use of the engine over time...
I can see you guys put a lot of work into these videos, they really are top-notch. Thank you.
Holley Carbs are one of the most popular carburetors for enthusiasts who like to build power and tune their higher horsepower large displacement engines.
If your engine has another brand of carburetor you still may be able to use the tuning info from our Holley DVD. You would just need to locate your Idle Mixture screws, idle speep screws and identify the power enrichment circuit for your Bosch carb. Sometimes there is are separate jetting systems for part throttle and wide open as well.
@93Patriot Sounds like the needle and seat assembly needs to be replaced, not just cleaned.
It's a standard procedure for any Holley carb as a regular service overhaul. The needle and seat is included with many of the complete rebuild kits as well.
Just start by getting a new pair of needle and seat assemblies and replace the one in each bowl. re-set the bowl level and your described problem should be solved.
Then you can think about the rest of tuning. Our Holley DVD can help if you like...
@marcelomeazzini
That's why we produced a 3 1/2 hour in partnership with Holley. They used to include the DVD in every box with new carbs.
You can get the full DVD from our BoxWrench site, but also search here at RUclips for other BoxWrench/Holley carb tuning clips.
Everything you'd need to know for tuning a Holly or most carbs is in our videos.
@3MAN09 Double Pumper carbs are most useful for use in higher horsepower engines with large camshaft profiles and/or manual transmissions.
They have four idle screws (one for each carb barrel) and also have dual accelerator pump systems (squirters) so you can more effectively tune the acceleration fuel demand curve for the higher HP types of engines.
They are most effective at eliminating 'flat' spots in the acceleration curve at the point where the secondary throttle plates open.
@adamslurch71 You would definitely need to have a larger displacement engine to even take advantage of a Holley Double Pumper.
The best way to determine if you've engine specifications are large enough to take advantage of the extra fuel delivery from a double pumper is to use the "Carburetor Calculator" at the Holley website. You answer some questions about your engine, RPM range and accessories, and it will guide you to the proper CFM size rating for your engine.
Seems like it may be a good set up for you. Only thing is the secondaries of the carb. With a manual transmission, you would possibly benefit from mechanical secondaries if your carb currently has vacuum secondaries.
Not a requirement though, just make sure to get your carb tuned properly with the help of a vacuum gauge and the proper jetting and idle settings.
Which port are you connecting the distributor vacuum line to?
It should be the one that exits the passenger side of the primary metering block...not any of the ports on the base of the carb.
That may have been a widely spread opinion years ago but people that don't like Holley carbs usually don't know how to tune them.
If you feel a "Flat Spot" in a Holley carb, it's definitely out of tune.
That's why we made these videos. There's nothing like them out there, definitely not from Edelbrock or Weber.
Every Holley carb comes with the DVD and using it will give you more knowledge of their carbs compared to any other brand out there.
At :21 seconds into this clip, the woman describes what "double pumper" means.
It just describes the fact that there are two accelerator pumps, one one the primary fuel bowl and one on the rear fuel bowl.
Two accelerator pumps also means there are two discharge nozzles.
The discharge nozzles (squirters) are solely responsible for making sure that enough fuel in introduced at the critical "lag" moment when the gas pedal is pressed.
Makes for better throttle response in a "Double Pumper"
I have a modified 350 and it has a Holley 700DP on it. We've been having trouble with it constantly loading up and flooding out. We have taken the carb apart, cleaned it, and frequently adjust the floats but it keeps flooding after running the car for a few trips. Unfortunatley it has come to the point that if we can not resolve the problem, the Holley will be coming off and being replaced with a Carter. Any ideas on what may be the problem?
Any ideas?
@93Patriot Give the new needle and seat assemblies a try and let us know what happens...
there will be a need to be a round of tuning that you go into when you have new seat assemblies, but you should hopefully solve the flooding issue.
Keep us posted.
Does that mean that you did a comparison between a Holley and the Q-Jet?
Did you actually try to tune a Holley before working with the Rochester?
If you followed the instructions in our Holley DVD, you'd have any Holley carb running pretty incredibly well...
We've had the opposite experience when comparing a tuned Holley to a tuned Q-Jet, we preferred the Holley every time.
Always wondered about double pumpers. Two fuel bowls. So do you have to run a second line from front bowl or does fuel get to second bowl internally somehow. Im new to double pumpers. Never had one.
Wow, this is an awesome video. Very informative and made the carb easy to understand. Thanks Boxwrench.
i take it double pumper means it takes twice the gas?
would i also need to install a nother fuel pump?
or jusy a high velocity pump with split lines?
Well I told my father who is much more of a mechanic then I am do to me only being 17 about what you suggested but he claims he already took it all apart, checked the needle and that it was fine. Is it possible that the damage is not visiable? Unfortunatley he already has a dislike for Holleys so it's becoming quite difficult for me to convince him to retry stuff such as replacing the needle which he feels isn't broken.
You need more accelerator pump shot to squirt more raw gas as you touch the pedal, just before the power valve and jet systems kick in.
too much to learn.haha..thats why i had my mechanic tune my 650 double pumper..n really loved my carb setup,really liked the holley,but i love the way quick fuel and proform carbs look...so ill be gettin myself one of those.
i have a carb question... Can i turn this carby around so the linkage are on the other side ....
@BoxWrench Hello I'm running a holley 650 DP on a 1.3L rotary engine. I know it's abit big a 500 would be more what I need for my set up. The engine will idle fine with the choke on but as soon as I take it off the carb leans out, engine high revs and its sputters till it dies. Anyone know what my problem could be? I'm leaning on a air leak. It's getting fuel fine but as soon as that choke is let off game over.
Maybe someone can help with this. 351 cleveland, holley carb. Driving slowly 2nd gear, mash the gas, dead spot and then wooosh. Why does it go dead for a second? Any advice?
ok i think i screwed up the adjustments on my carb.i think it runs a bit rich and when i mash the gas it damn near dies then goes
mechanical only means the secondaries are open mechanically not with engine vacuum. You can run vac dist and canisters with mechanical carbs. Note mechanical has pros along with cons as compared to vacuum secondary carbs
dose holly make something for carburated hondas
Is there a video like this for a Q-JET 4brrl by Rochester?
@BoxWrench So even if the Holley is brand new?
check your fuel line for a crimp. i was wondering why mine would bog when i reved it, the fucking motor pinched its own fuel line from rocking when under a load. crazy crazy shit.
i had it checked by a GM dealership and they said it was a bad wire that can not be located inside the wiring harness
long time ago i modifid rochester for racing that worked muche beter on 350 chevy for drag and street racing i did not beleve it will but it was one of the best things i ever done .
@BoxWrench Thank you for the help. I really appreciate it.
Is this compatible with a 1990 GMC Suburban?
im getting a buick 455 that can come with or with out one of these. 400 without --450 with. im taking the carb.
whats so good about a double pumper?
Is this compatible with GMC 2500 Suburban?
i would keep the 650. A bigger carb would only help you if you had a larger ci small block 383 or 400 or rpm aboove 6500. Putting a bigger carb will most liklely slow you down, foul plugs, bog off idel etc.. I had good luck with a edel 600 cfm on a 350 street motor. I put a 750 on my 406 small block but it had 11.5 cr and a .555 solid lifer cam rpms were 3-6500.
That's a great video. Thanks for posting.
ur damn right, i hate fuel injected i have a 85 camaro with a tuned port 5.7 and i hate it, i mean its fast and all but i have nothing but problems with it
so dont watch it and if u think its boring and u watch it then keep ur mouth to urself cuz this shit is helpful
for small block chevy Q-jet workes allmost all the time beter ,i try tune holley it was fine but not very sharp some time you get flat spots in US you can have jet kits to fine tune it power valves but Q-jet is more responsive with small block and very important thing if you go street racing then Q-jet is realy shining.
It´s impossible to tune without instruction manual
The black rubber diaphragm doesn't last long with 10% pump gas.
@93Patriot Unless your dad is using the carb on a race application engine, toss that POS Holley in the trash & snag a good ol' Carter/Edelbrock AVS. much easier to tune & they won't give you the problems you'll continue to encounter with the Holley carbs.
We apologize, this store is currently unavailable
Jay Malinowski Please when will be possible buy your fantastic DVD? I built my 1° engine following your instruction! Please fix the website !!! PLEASEEEEE
as soon as she said the famous holley double pumper i was like god thats hot
I want her to pump my holley >:)
Great video!
carbs are not my forte. i think i need a manual!
This is a very interesting video :P
Holley carbs should be called flat spotters!
just buy a webber.
There's just something about a sexy girls voice saying "Holley Double Pumper"
gas prices r droppin by the second =D
Fukk errythang els holly is the shiitttt!!!!!!!!!
no! :-)
I am just pointing out that hollies have a bad reputation for flatspots, thats why they have to give so much info with their carbs.
Why do u think the ford GT40 used a bank of webers and not holley?
holley is good for pouring fuel into big engines with so much torque that flat spots do not matter as much, but for quality, accuracy etc webber is far better.
Bizare that u would use insults to convey ur opinion, r u one of those wierdos that falls in love with objects? like men who fuck cars?
boring