Some gaskets need RTV in the corners, not sure about those but it is
handy to have.
I think you will need headers and maybe dual exhaust as well. The last
4 bbl swap I helped a friend do turned it into a pig because of stock
exhaust manifolds and single pipe. It only sounded cool. We changed it
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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.
Wasn't there a 340 cid engine available about that time which was
the 318 punched out? Seems that I helped a friend swap a 340 in place of
318 in a Duster, but may be confused. I know for sure he installed a 4
barrel on it.
With all the modifications he eventually performed, this project evolved to
monster. He could lift the front wheels off the ground - seriously- in low
Im going to answer my own post. Researched it and found the 340 Dodge was
available around the OPs model date. It was rated at 275 BHP and with a
tweaking could put out a lot more than that. I believe that manifolds, and
other parts interchange with the 318.
Original intake and exhaust manifolds are rarer than hens teeth,
Yes, parts will interchange, the intake manifold will fit but
there will be a severe port mis-match, exhaust manifolds off of a
71-72 C-body 360 will fit the 318 and flow a lot better than the
318 manifolds. 360 "J" heads flow as well as the 340 heads and
are still found in salvage yards, one needs to be careful with
them on a 318 WRT valve size, too big of valve and you have
shrouding problems with the cylinder wall.
And no, the 340 wasn't a punched out 318 any more than a Chebby
350 is/was a punched out 265.
.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.
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...
Yep, yep, yep....
timing chain and sprockets were different, main and
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. :-)
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.
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!
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.
Probably not.... I did an exchange on a 63 galaxy... from a 2 barrel to
a 4 barrel. I used an Edelbrock high rise manifold with a Holley 4 barrel
(650 cfm) and (I believe) an adapter for the carb. It may have already come
with the kit though... that was many years ago... let me tell you...... it
made an extreme amount of difference in the cars performance. I was
literally shocked at how much power I got just from that small change.
You may want to talk to the place you got the parts from to see if you
are missing something
Sure it did. 80s M-body copcars. Or use parts of a 360 4-bbl pickup
truck. The 318 and 360 are dimensionally identical, and anything that
bolts onto a 360 (above the oil pan, anyway) will bolt on a 318.
Yeah, with the appropriate 4-bbl intake manifold, and the right gaskets,
all that's left is the linkage hookup, and that isn't much more than a
bit of fussing. Be alert to the possible need for a new air cleaner
assembly to fit the 4-bbl throat.
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