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What do I need to change my 2 barrel to a 4 barrel



 
 
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  #21  
Old April 29th 06, 02:48 AM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel

In article > ,
> wrote:

> "aarcuda69062" > wrote in message
> ...
>
> > And no, the 340 wasn't a punched out 318 any more than a Chebby
> > 350 is/was a punched out 265.

>
> Would look like basically a bore job. Stroke was 3.31, bore was 3.91 on
> the 318 and 4.04 on the 340.


..130 inches different. Boring out would require a .065 inch cut,
that equals roughly 1/3 the thickness of the cylinder wall.
It'll run, but it'll probably sag in short order.

> 318 (5.2) 1967-2002 3.31 3.91
> 340 1968-73 3.31 4.04
>
>
>
>
>
> What are the other differences, Aarcuda?


The blocks were different although the early 360s shared the same
block casting number as the 340. Cylinder centers are the same,
deck heights are the same, rods are different weight and casting
number from what I've observed, cylinder heads are different in
both valve size and combustion chamber volume, camshafts were
different, timing chain and sprockets were different, main and
rod bearings were different, different water pump, larger
diameter by-pass hose, different ring groove depth in the
pistons, different valve springs, different oil filter mount...
Ads
  #22  
Old April 29th 06, 11:36 PM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel


"aarcuda69062" > wrote in message
...
> > What are the other differences, Aarcuda?

>
> The blocks were different although the early 360s shared the same
> block casting number as the 340. Cylinder centers are the same,
> deck heights are the same, rods are different weight and casting
> number from what I've observed, cylinder heads are different in
> both valve size and combustion chamber volume, camshafts were
> different, timing chain and sprockets were different, main and
> rod bearings were different, different water pump, larger
> diameter by-pass hose, different ring groove depth in the
> pistons, different valve springs, different oil filter mount...


Considerable differences, for something that 'looks like a duck'.
Thanks


  #23  
Old May 1st 06, 08:26 PM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel

wrote:

> "Steve" > wrote in message
>
>
>>But you don't NEED headers. A 4-bbl and dual exhaust (don't forget the
>>crossover!) are a nice mild wake-up for a 318. To take full advantage of
>>headers, you'd really need a bigger than stock cam and exhaust port
>>work. Headers won't HURT, but put your money elsewhere first.

>
>
> Steve,
> Wasn't there a 340 cid engine available about that time which was
> essentially
> the 318 punched out? Seems that I helped a friend swap a 340 in place of
> his
> 318 in a Duster, but may be confused. I know for sure he installed a 4
> barrel on it.



A 340 is indeed the basic 273/318 block with bore size increased, a
forged crank, always with a 4-bbl, and DIFFERENT HEADS :-) The problem
with doing a factory parts mix-and-match on a 318 is that putting either
340 or 360 heads on it (to get the bigger ports that flow better) also
comes at the expense of getting a larger combustion chamber that would
lower the compression ratio to about 7:1 without other added changes :-/
Best "bolt-on and go" heads for a 318 are the 80s "swirl-port" XXX302
casting with minor work to clean up the ports. Now if you start to
change the bottom end and can pick pistons with a higher than factory
deck height, then sure, use 360 heads and have the best of both worlds!
>
> With all the modifications he eventually performed, this project evolved to
> a
> monster. He could lift the front wheels off the ground - seriously- in low
> gear.


The 340 gets my vote as the best high-performance smallblock v8 ever.
Screw the chevy 350, its good but it doesn't come CLOSE to a 340. A 340
will humiliate most big-blocks, and still leave the front end light
enough to set up for handling as well. Sadly, they only built about 1
340 for maybe every 50 small Chevies ever made. And probably 1 340 for
every 20 318s, for that matter.


  #24  
Old May 1st 06, 08:30 PM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel

aarcuda69062 wrote:


>
> And no, the 340 wasn't a punched out 318 any more than a Chebby
> 350 is/was a punched out 265.


In other words, it is a punched out 318 (273, actually) in CONCEPT, but
not in practice. Same block archetecture- deck height, crank geometry,
bore spacing, bolt patterns, etc. But in practice the cylinder castincg
cores were changed so the block casting is internally different. If you
could REALLY "punch out" (ie bore) a 318 to 340 size, the 318 would have
inch-thick (a slight exaggeration) cylinder walls. The 360 goes a little
further in that the main bearing webs are different to accept larger
diameter main bearings.



  #25  
Old May 1st 06, 08:34 PM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel


> The blocks were different although the early 360s shared the same
> block casting number as the 340. Cylinder centers are the same,
> deck heights are the same, rods are different weight and casting
> number from what I've observed, cylinder heads are different in
> both valve size and combustion chamber volume, camshafts were
> different,


Yep, yep, yep....
timing chain and sprockets were different, main and
> rod bearings were different, different water pump, larger
> diameter by-pass hose, different ring groove depth in the
> pistons, different valve springs, different oil filter mount...


Now all THAT stuff is year-dependent as well. By the time the 340 was
being replaced by the 360, for example, all 3 engines were using the
same timing case/water pump castings and the bypass hoses were the same,
but in earlier years they differed. Sorta the same for rods- the 318
started out using the lighter 273 rods and floating pins, but in late
73/early 74 or about, it went to the 360 rod with a pressed pin. It gets
real interesting when a single engine architecture stays in production
for >40 years. :-)


  #26  
Old December 21st 19, 02:49 AM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel

What if it is a boat that I'm trying to convert
  #27  
Old December 21st 19, 02:58 AM posted to rec.autos.tech
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Default What do I need to change my 2 barrel to a 4 barrel

I have a boat with a 2bbl holly carb want to convert to a 4bbl carb
  #29  
Old December 21st 19, 11:28 PM posted to rec.autos.tech
AMuzi
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Posts: 488
Default What do I need to change my 2 barrel to a 4 barrel

On 12/20/2019 7:49 PM, wrote:
> What if it is a boat that I'm trying to convert
>


The matching intake manifold? Is this a trick question?

http://www.2040-parts.com/_content/i...7/6797/001.jpg

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971


  #30  
Old December 22nd 19, 07:23 AM posted to rec.autos.tech
Xeno
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Posts: 363
Default What do I need to change my 2 barrel to a 4 barrel

On 21/12/19 12:49 pm, wrote:
> What if it is a boat that I'm trying to convert
>

First you need to understand the problem.
I suggest you get hold of these books;

Practical Engine Airflow - John Baechtel

Performance Automotive Math - John Baechtel

Then, when you understand how the engine breathes and, more importantly,
makes torque, you will be in a better position to use this website;

https://www.holley.com/retailer/carbselector/

Of course, you need to consider the type of use. A boat is a little
different from a car since you use the prop loading to control engine
RPM, gearbox not required - except for reversing and idling.


--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)
 




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