2bbl or 4bbl ????????????????
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Senior User
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From: Kent, WA
2bbl or 4bbl ????????????????
I have a 65' F-250 4x4 with a 352 in it. Currently I have a Holley 2bbl on the truck. It runs really good, but I would like to have more power. I have everything to adapt my Holley 600 on the truck. My question is, how much of an increase of power will I notice. Keep in mind that this truck is my daily driver, and I do take it off road from time to time. Will the 4 bbl increase or lower my gas mileage???? Thanks
Fleet Owner
Joined: Jun 1999
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From: Creedmoor, North Carolina
2bbl or 4bbl ????????????????
Mitch, If you have all of the parts and the skill, put them in, I didn't notice much difference installing a 4 barrel. I have a new 390 still on the stand waiting for the rest of the truck to be finished and I stayed with the 2 barrel and stock manifolds. The 4 barrel will use more gas because you will keep your toe in it more. 
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Joined: May 2002
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2bbl or 4bbl ????????????????
I went from a holley 500 cfm 2 bbl to a 600 vaccuum 4bbl and the only noticable change was worse fuel milage. My opinion, on a driver if it works well now leave it alone. Now if I could only take my own advise.
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From: Louisville,Ky.
2bbl or 4bbl ????????????????
Are you changing in intake manifold too? Don't use a 2bbl to 4bbl adapter, this will kill alot of power. If the 4bbl is jetted right and you keep your foot out of it, a 4bbl will get better mileage because the front 2 bbls are smaller than the ones on the 2bbl. Another benifit to going with a 4bbl is if you go to an aluminum intake you will save a ton of weight off of the front og the truck. When I pulled the stock intake off of my 460, I didn't think that I would ever stand up straight again. My Edelbrock Performer is so much easier to handle.
Jimmy
Jimmy
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From: Kent, WA
2bbl or 4bbl ????????????????
I am going to use a stock cast iron 4 bbl manifold. I can't justify spending the money on an aluminum intake when it don't offer any benefits, except for weight. My truck is so heavy anyways, another 50 lbs. ain't gonna make too much of a difference. Plus my 4bbl manifold was free so... Wouldn't my highway gas mileage be better with the 4 bbl? I know my town mileage will suffer. I have to take my intake manifold off anyways because it's leaking reallly bad out of the rear manifold seal. So I figure if I have it off why not put a 4 bbl on there. But my other dilema is "If it ain't broke don't fix it".
Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
2bbl or 4bbl ????????????????
Mitch, I read most every post here, 67-72, and FE. I read more constant tuning problems with Holley, and if your truck isn't rebuilt for the use of more gas, you are wasting your time, and you are familier with the "if it aint broke thing".
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In the cool still quiet of night, you can hear chevies rusting away.
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John
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In the cool still quiet of night, you can hear chevies rusting away.
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Joined: Aug 2002
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From: USA
2bbl or 4bbl ????????????????
In reply to mwc4275
From my experience, 2bbl carbs make much more low-end torque than 4bbl carbs do. All a 4bbl carb will do for your motor is increase power in the upper end of the rev range, due to the increased cfm and fuel flow. It's purely up to you to change or not, but I recommend keeping the 2bbl if you go offroading, especially if you have the stock truck cam. You will need the low-end torque. I'm sure you're not driving like it's the Baja 1000 or anything, and I doubt you are racing on the streets.
The 2bbl will serve you much better, IMHO, for the uses that you stated. The 4bbl will trade low-end torque and possibly a few mpg for more power in the upper end of the powerband. A better cam would reap more benefits from the 4bbl than the stock truck cam will. In that case, a 4bbl would be beneficial.
If in the future you decide you do want more overall power, I recommend the Autolite 4100 over any Holley. They are a much better carb, and they are period-correct.
-Zen-
From my experience, 2bbl carbs make much more low-end torque than 4bbl carbs do. All a 4bbl carb will do for your motor is increase power in the upper end of the rev range, due to the increased cfm and fuel flow. It's purely up to you to change or not, but I recommend keeping the 2bbl if you go offroading, especially if you have the stock truck cam. You will need the low-end torque. I'm sure you're not driving like it's the Baja 1000 or anything, and I doubt you are racing on the streets.
The 2bbl will serve you much better, IMHO, for the uses that you stated. The 4bbl will trade low-end torque and possibly a few mpg for more power in the upper end of the powerband. A better cam would reap more benefits from the 4bbl than the stock truck cam will. In that case, a 4bbl would be beneficial.
If in the future you decide you do want more overall power, I recommend the Autolite 4100 over any Holley. They are a much better carb, and they are period-correct.
-Zen-
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Thread Starter
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Senior User
Joined: Mar 2002
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From: Kent, WA
2bbl or 4bbl ????????????????
Thanks for all of the reply's. I have to take my intake off anyways, so I think I wil throw on the 4bbl stuff just to see what happens. But I will keep my 2bbl setup handy just in case.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
2bbl or 4bbl ????????????????
That's exactly what I hear the Holley is the most tuned carb around. If you put the 4 barrel on pitch the old stuff, because you'd be a dang fool to go to all of the trouble to take the 4 barrel back off. That is a day long job.
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John
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[link:www.ford-trucks.net/users/jowilker/NCFTE.html|NCFTO] North Carolina Ford Truck Owners Group
In the cool still quiet of night, you can hear chevies rusting away.
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John
jowilker email me
[link:www.ford-trucks.com/users/jowilker|My Club FTE Page] Member since 01 01
[link:www.ford-trucks.net/users/jowilker/NCFTE.html|NCFTO] North Carolina Ford Truck Owners Group
In the cool still quiet of night, you can hear chevies rusting away.
Senior User
Joined: Aug 2002
Posts: 175
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2bbl or 4bbl ????????????????
years and wives ago i had a f100 ranger, camper special.
352 2v. bolted in a rebuilt 352, but still needed heads. bought a pair of double sprung 390 heads from a friend, added a unknown 4v manifold,with a holley 600, and headers, with duals. the thing went like a raped ape. wish i still had it. also had adjustable rockers from an old t bird 352. bought em right of the shelf.
352 2v. bolted in a rebuilt 352, but still needed heads. bought a pair of double sprung 390 heads from a friend, added a unknown 4v manifold,with a holley 600, and headers, with duals. the thing went like a raped ape. wish i still had it. also had adjustable rockers from an old t bird 352. bought em right of the shelf.
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Senior User
Joined: Mar 2002
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From: Kent, WA
2bbl or 4bbl ????????????????
Well I got the carburator rebuilt yesterday and tomorrow I'm going to make the swap. Got everything figured out already except for the throttle linkage. I might have to change it I'm not sure. Just one of those things I have to figure out as I go.