Questions about Big Block Chevy Tall Deck Engines

[Greg Hermann]

>
>
> Don't know just where to go for help with this kind of
> information. Any answers or leads gratefully appreciated.
>
> 1. What was the bore and stroke of the 366 engine?
>
> 2. What is the purpose of the tall deck engines used in trucks?
> Bore and stroke are the same as passenger engines (standard deck
> height)so is it for better water circulation? DURABILITY
>
> 3. Apparently they have the same bore and stroke as standard deck
> height engines, so can standard cranks and rods be used? Are the
> heads the same? DON"T THINK SO FOR RODS>
>
> 4.  intake manifolds and
> water pumps are different to allow for better cooling AND FOR FIT UP WITH
>TALLER DECKS
>
> Hope there is some engine historian out there who can help me out
> on this. I'm trying to put together a 1970 C-50 truck with a 427
> engine. The block and crank may be bad on this one (I haven't
> taken it apart yet) but I know where to get several 366 engines.
> Want to figure out if I can put a longer stroke crank in a 366
> (and what displacement will it give) or if I can slip a 454 block
> under the 427 truck heads and manifold.

Tom's post looks accurate as to the numbers, except that I think that the
truck (tall) blocks all used much longer rods. Seems like one inch of deck
height would be quite a lot to make up in the compression height of the
pistons! Also, what would the point have been to raise decks without
reducing rod angularity.

Also-very significant-- all tall deck truck motors used a forged steel
crank. VERY valuable piece for a serious engine. Strokes were same , as Tom
noted, but I think that counterweight bobs were different from one
displacement to another. Do not know which displacements, especially for
the tall decks, were internally balanced vs. externally balanced--but if
you use "Mallory metal" slugs to rebalance (internally) , who cares which
one the crank started out as--therefore any 366 should be a good source for
a good steel crank at a reasonable price! Presumably, piston weight is
changing anyway, so you will HAVE to balance it anyway--only extra cost is
for the sintered tungsten/osmium ("Mallory") slugs, and the 366 cranks are
a LOT cheaper. Plus, an internally balanced crank runs under a lot less
stress, as does its block. Whatever else you do, use a Fluidamper--it will
make you wonder why the rod bearings last three times longer!!!

The longer rod length in the tall deck motors adds considerably to
otherwise very poor durability under constant high load usage. Well worth
it. A short deck block in a marine application is only good for 2 or 3
hundred hours before leakdown rates escalate. A tall deck is good for more
like 5 to 7 hundred hours. (Of course, RB Mopars and 385 Fords will go over
1000 hours in similar usage without much trouble. :-) <ducking>)

You will need a block that started out life with a bore in the size range
which you want to end up with. Water jacket coring changed from bore size
to bore size, and trying to overbore a small bore block (by a large amount)
will lead pretty quickly to a swimming lesson.

Regards, Greg