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Originally Posted by rsimoes
Thanks for the feedback, but these are the questions that I am trying to get answers to. Also, is a 4.5 stroke on the FE really a bad idea?
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One reason why a 4.5 stroke is a bad idea in an FE comes down to compression height. Using such a long stroke crank in an FE raises
the same problem people run into with big inch Windsors. Assuming
a standard deck height FE block, (10.17") 4.5" crank, and 6.7 BBC rods,
the compression height comes out to 1.22 at zero deck clearance. We
could gain some height using FE length rods (6.48) and get a compression
height of 1.44. Better, but then we are already going from an already
marginal rod length/stroke ratio with 6.7 rods and making it more marginal
with shorter rods. When you get into extremely short compression heights,
you start running out of room for the ring pack. So you have to use thinner
rings and shorter spacing between the rings to keep the ring grooves away
from the wrist pin bores. Purpose built race motors such those in NASCAR
have extremely short compression heights but being that they are not
built for longevity, it isn't that much of a factor. Workarounds include
simply letting the ring area overlap the wrist pin bore and reducing
wrist pin diameter. That's fine for race engines, but probably not so good
for an engine expected to live a long time with minimal
oil consumption.
Theoretically, it is possible to put this combination together, but it will
be expensive as you'll need a both a custom crank and custom pistons and it
may have a relatively short life. As others have mentioned, going with one
of proven FE combinations such as the 482 or 496 will cost considerably
less and give you a reasonable lifetime.
....Fred