413 vs 400 engine swap

[William Parker <parkerw@xxxxxxxxxxxxxxxxxxxxxx>]

My .02 worth, the short block is essentially the same piece,
it is the heads that make a difference in performance.  The
413 stock heads are closed chamber, nominal 10:1 static
compression ratio with the stock flat top pistons.  '66 and
'67 440 heads had closed chambers also, the '67 440 head is
the "915" head with closed chambers but larger ports and
valves than earlier heads.  The "906" head used beginning in
'68, and later heads, are open chamber, giving a lower
static compression ratio with flat top pistons.  The primary
exception in the 413 head is the maximum performance head
(the "286" head), which is a semi-open chamber head and
needs domed pistons to make better compression ratio.  My
max wedge heads are at the machine shop right now, and they
just CC'ed the chambers last week, all were 86.5 CC to 87.5
CC on a nominal 87 CC spec, this is  bigger than the
standard 413 head which if I recall is spec'ed at 76 CC, I
may have that wrong.  The drawback to using the 413 then
comes down to bore size.  The smaller bore shrouds the
valves a bit more, in fact for the max wedge engines the
bores are notched for the intake valves, which still leads
to shrouding.  However, for a basic rebuild without
springing for new heads, etc, you'll keep a better
compression ratio with the 413 than you'll get with most
440's you might run across in a salvage yard.  That static
compression ratio, and high cranking compression if you are
running a stock spec cam, give you better throttle response
and torque.  I generally have been able to run 10:1 or
10.5:1 static ratio in the engines I build for myself with
no problem using premium gas and still keeping the total
mechanical timing up around 34 degrees.  My Cuda 340 has
Speed-Pro mildly-domed pistons, nominally 10.5:1, with "J"
340/360 heads, I love the way it winds up sharply whenever I
hit the throttle, however it does have a warm cam to bleed
off cranking compression.

One other consideration is replacement pistons if you need
them.  somewhat difficult to find at this time.  The Badger
brand has discontinued them but distributors may still have
some in stock, I acquired a .030 set that way last year, by
calling a distributor.  KB and Silvo-Lite have only low
compression and very heavy truck motor pistons.  So for a
ring-and-bearing job, I think I would stay with the 413, but
if it needs pistons, that alone may make you acquire a 440.

-- 
Bill Parker, South Central Indiana
'62 Plymouth Max Wedge; '64 Dart Convertible (Kathi's car);
'65 Imperial; '65 Barracuda \6 (Kathi's other car);'68
Barracuda Fastback 340-S; '69 Barracuda Fastback now 360 (20
y.o. son's car); '72 Cuda 340