George Farrell
Donation Time
I'm doing a 2.8 conversion and am more interested in driveability and economy than maximum performance. Is the stock carb setup a good one? Would a four-barrel be a better choice?
George
George
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Enjoy.
Two-barrel or four?
- Thread starter George Farrell
- Start date
Hi George,
The four barrel is a better choice, because it will give better mileage and Power than the stock two barrel. The stock two barrel has about 250 cfm., while the four barrel has just 390. This means that the primary barrels are only 195 cfm between them. The smaller barrels will carburete better, so are a bit crisper on acceleration when just driving around town. The two barrel carb has the full 250 cfm. all the time, so isn't as crisp around town, and also doesn't have the extra cfm. when you have the throttel wide open.
The four barrel will give better mileage too (as long as you don't have your foot in it), b4ecause it is flowing less air. For the best all around performance, I have found the Holley four barrel to be better.
Jose
The four barrel is a better choice, because it will give better mileage and Power than the stock two barrel. The stock two barrel has about 250 cfm., while the four barrel has just 390. This means that the primary barrels are only 195 cfm between them. The smaller barrels will carburete better, so are a bit crisper on acceleration when just driving around town. The two barrel carb has the full 250 cfm. all the time, so isn't as crisp around town, and also doesn't have the extra cfm. when you have the throttel wide open.
The four barrel will give better mileage too (as long as you don't have your foot in it), b4ecause it is flowing less air. For the best all around performance, I have found the Holley four barrel to be better.
Jose
George, how about bolt on (junkyard) electronic fuel injection? I would bet it is better than either carb setup.
http://www.therangerstation.com/tech_library/2_8_FuelInjection.html
Bill
http://www.therangerstation.com/tech_library/2_8_FuelInjection.html
Bill
Economy...
Jose,
Yup, I'm sure going to try to remember that! Foot out of the gas=Good economy. I'll put a sign on the dash of Series v6.2 to remind me....
I figure with all the hybrids out there and the ones to come, it's my obligation to burn fossil fuels when I can. Gotta do something with it. Can't eat the stuff. I'll go green with my daily car.
The four barrel will give better mileage too (as long as you don't have your foot in it Jose
Jose,
Yup, I'm sure going to try to remember that! Foot out of the gas=Good economy.
I'll put a sign on the dash of Series v6.2 to remind me....I figure with all the hybrids out there and the ones to come, it's my obligation to burn fossil fuels when I can. Gotta do something with it. Can't eat the stuff. I'll go green with my daily car.
I have a 2 barrel 390cfm holley on my 3.4. And it goes like a rocket. (I have to get wider tires next year) One pleasant surprise was that Autozone stocks the gaskets ,needle valve and a few other bits for the Holley.
Mine is a marine version, but the 2 barrel circle track (4200 series I think) look really tempting.
If you switch carbs, the first problem is the adapter. I made one with an aluminum plate. And to be honest, I have a 4 barrel in the basement and the base is huge. The 2 barrel sits nicely over the original (sort of) manifold.
As for FI, a crank or knock sensor may be hard to setup on an older engine. I've read many posts about the carb being archaic, but I'm happy with it. And actually, it seems like I get good milage. The engine certaily doesn't work very hard.
Mike
Mike
Mine is a marine version, but the 2 barrel circle track (4200 series I think) look really tempting.
If you switch carbs, the first problem is the adapter. I made one with an aluminum plate. And to be honest, I have a 4 barrel in the basement and the base is huge. The 2 barrel sits nicely over the original (sort of) manifold.
As for FI, a crank or knock sensor may be hard to setup on an older engine. I've read many posts about the carb being archaic, but I'm happy with it. And actually, it seems like I get good milage. The engine certaily doesn't work very hard.
Mike
Mike
Yes I see. This one isn't controlling the spark, only the mixture.
Pretty hard to know which is better. A better carb or FI without trying both. But you can be sure that a carb will be a lot easier.
Don't forget you need a swirlpot and all that high pressure fuel stuff too. A carb needs about 4psi, and a throttle body needs about 40psi.
Pretty hard to know which is better. A better carb or FI without trying both. But you can be sure that a carb will be a lot easier.
Don't forget you need a swirlpot and all that high pressure fuel stuff too. A carb needs about 4psi, and a throttle body needs about 40psi.
Swirlpot? What's that? I've never heard of that term.
No doubt the EFI will be a lot of work, mostly the wiring. But the up side is that after the work is done, the damn thing is drivable with a combo of drivability, power and economy that you'd never have with a carburetor. Also, I think it could very well cost less than a four bbl setup.
Bill
No doubt the EFI will be a lot of work, mostly the wiring. But the up side is that after the work is done, the damn thing is drivable with a combo of drivability, power and economy that you'd never have with a carburetor. Also, I think it could very well cost less than a four bbl setup.
Bill
Hi Bill,
The FI requires a high pressure fuel pump and a fuel regulator. Fuel that is released by the regulator but not used by the injectors is returned to the fuel system via the swirl pot. (this is what your car does presently). The swirl pot collects the unused fuel and makes it available to the high pressure line.
As I write this, I'm wondering how fuel will be injected into the system. Some older systems used a single injector near the throttle body.
Anyway, I won't debate the cost. But I think the 4200 Holley is about $250 new. If that's more or less is for you to decide.
The FI requires a high pressure fuel pump and a fuel regulator. Fuel that is released by the regulator but not used by the injectors is returned to the fuel system via the swirl pot. (this is what your car does presently). The swirl pot collects the unused fuel and makes it available to the high pressure line.
As I write this, I'm wondering how fuel will be injected into the system. Some older systems used a single injector near the throttle body.
Anyway, I won't debate the cost. But I think the 4200 Holley is about $250 new. If that's more or less is for you to decide.
RootesRacer
Donation Time
Huh?
Many race cars use a device like what you describe (save that it goes to an intermediate low pressure reservoir), but semi-modern EFI cars just return the surplus fuel to the tank.
Many newer cars dont even have a regulator and use the pump to dead head regulate rail pressure.
The TBI unit Bill was referring to has its fuel pressure regulator built in, so that leaves you to find a fuel pump, some sensors and an EFI controller.
Said TBI unit bolts to a 2bbl ford intake (that comes stock on post 74 2bbl carb'd 2.8s).
Just as an addendum. Modern cars uses pressurized tanks and the fuel pump in in the tank. Typically what is done in the case of cars such as ours is that a low pressure pump first pumps fuel into the swirl pot (also because the high pressure pumps are not self priming) then the HP pump takes over and sends the fuel to the injector system. Overflow is returned to the swirl pot vs the tank. The reason for the swirl pot is to ensure that air bubbles are not intruduced into the fuel, then returned to the injector.
There is plenty of discussion on this at www.mgexperience.com
You can see why I choose to remove all the EFI on my engine. For an old guy like me, it was just too complicated. And expensive.
There is plenty of discussion on this at www.mgexperience.com
You can see why I choose to remove all the EFI on my engine. For an old guy like me, it was just too complicated. And expensive.
RootesRacer
Donation Time
What you are calling a swirl pot is inside the tank and is a baffled box, there to allow the pickup to pull fuel instead of sucking air when the tank is low and the car corners.
When most people install aftermarket EFI on old cars such as ours, they do not install what you are calling a swirl pot, I have installed EFI on dozens of cars, and the only time I have ever been tempted was if the car was to be raced.
Adding an extra pump and an external intermediate reservoir is bulky, clumsy lowers reliability and tends to overheat the fuel since only a small amount of fuel gets pumped from the reservoir to the fuel rail back to the fuel rail ad-infinitum.
Only the extra fuel pumped in from the tank (to compensate for the fuel consumed by the engine) cools the ever increasing fuel temp in the reservoir.
When most people install aftermarket EFI on old cars such as ours, they do not install what you are calling a swirl pot, I have installed EFI on dozens of cars, and the only time I have ever been tempted was if the car was to be raced.
Adding an extra pump and an external intermediate reservoir is bulky, clumsy lowers reliability and tends to overheat the fuel since only a small amount of fuel gets pumped from the reservoir to the fuel rail back to the fuel rail ad-infinitum.
Only the extra fuel pumped in from the tank (to compensate for the fuel consumed by the engine) cools the ever increasing fuel temp in the reservoir.
As I mentioned I choose not to use EFI based on everything I read and the associated cost.
Here is a very good article on what we are disussing;
http://www.fortunecity.com/silverstone/impala/1012/cars/tech/swirl/swirlfaq.html
Mike
Here is a very good article on what we are disussing;
http://www.fortunecity.com/silverstone/impala/1012/cars/tech/swirl/swirlfaq.html
Mike