Better Fuel Economy: 2 or 4 Barrel Carb?

Have an AMC 360 V-8, 2bbl. Would putting smaller jets in the 2 help, or put
a 4 barrel on the engine. Car has only 27K original miles.

On 12/20/2012 05:54 AM, sctvguy1 wrote:
> Have an AMC 360 V-8, 2bbl. Would putting smaller jets in the 2 help, or put
> a 4 barrel on the engine. Car has only 27K original miles.

convert to throttle body injection.


--
fact check required

sctvguy1 wrote:
> Have an AMC 360 V-8, 2bbl. Would putting smaller jets in the 2 help, or put
> a 4 barrel on the engine. Car has only 27K original miles.

No miracle mileage cures for carbed engines of that era. The 360 isn't a
mileage engine. It's a lot like all the other small blocks. They are
reliable, solid good running engines, BUT none of them are great on
fuel. Trying to lean them out usually just causes more problems.


Out of the stated options though I would opt for a Q-Jet replacement.
Then keep your foot out of the secondaries. The main bores on the Q are
generally smaller than a 2 barrel and will give you some benefit. They
actually are a great carb once you learn how to deal with them.

--
Steve W.

>On 12/20/2012 05:54 AM, sctvguy1 wrote:
>> Have an AMC 360 V-8, 2bbl. Would putting smaller jets in the 2 help, or put
>> a 4 barrel on the engine. Car has only 27K original miles.
>
>convert to throttle body injection.

TBI will probably improve your reliability and reduce the amount of time you
spend tinkering around.

But really, if you're worried about mileage, that's the wrong engine. There
is a reason it only has 27k miles on it, no one could afford the gas bills.
I don't think injection will really improve that very much. You will waste
a little less gas with a cold engine and you might be able to safely lean it
out a bit, but it's the difference between an incredibly huge gas bill and
a barely-credibly huge gas bill at best.

If it were mine I would keep it stock and I would probably keep it parked too.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Thu, 20 Dec 2012 08:54:21 -0500, sctvguy1 >
wrote:

>Have an AMC 360 V-8, 2bbl. Would putting smaller jets in the 2 help, or put
>a 4 barrel on the engine. Car has only 27K original miles.

You won't get better mileage with a 4 barrel IMHO. And if you do get
marginally better mileage how many miles will you have to drive to
make up for the cost of changing out the carb? If it's running good
just leave it alone. You could try smaller jets and see what happens
or take it to a place with a dyno and exhaust gas analyzer and see
what the exhaust tells you about it's current jet size. But like I
mention above, how many miles of driving will you have to do to get
back the cost of the shop testing and any subsequent changes to the
carb? If it's running good just leave it alone.

On 12/21/2012 01:44 AM, Ashton Crusher wrote:
> On Thu, 20 Dec 2012 08:54:21 -0500, sctvguy1 >
> wrote:
>
>> Have an AMC 360 V-8, 2bbl. Would putting smaller jets in the 2 help, or put
>> a 4 barrel on the engine. Car has only 27K original miles.
>
> You won't get better mileage with a 4 barrel IMHO. And if you do get
> marginally better mileage how many miles will you have to drive to
> make up for the cost of changing out the carb? If it's running good
> just leave it alone. You could try smaller jets and see what happens
> or take it to a place with a dyno and exhaust gas analyzer and see
> what the exhaust tells you about it's current jet size. But like I
> mention above, how many miles of driving will you have to do to get
> back the cost of the shop testing and any subsequent changes to the
> carb? If it's running good just leave it alone.
>

Honestly, a NEW carb properly tuned will make an improvement in economy
(either 2bbl or 4bbl)

I personally would go for something like an Edelbrock Thunder Series
(Carter AVS clone)

That said, you by the time you buy the carb, manifold, and rod/jet kit
and pay someone to dial it in... you'll never make that money back in
saved fuel. If you really want to swap to a 4bbl do it because you want
to and because it makes you happy to have the car running its best, but
fuel savings... naah, probably not worth it.

nate

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replace "roosters" with "cox" to reply.
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The primaries in a qjet are smaller then a 2 barrel primaries you will get better gas mileage with a qjet then a Rochester 2 barrel anyone that says otherwise is dumb. Just stay light on the pedal and keel the secondaries shut your be fine.