Very interesting, Daniel...
Thanx for providing a little background as
to why the alum. head seems to work so
well. Everything "the David's" did was checked out on a flow bench so if
Pierce
used APT's technology in these respects, this would speak for itself.
My engine neither sports a hairy cam or
high CR, yet goes like hell in terms of
street torque (low/mid-range). My bet is
that the small bore of the stock 1.25 carb.
set-up is keeping up the "velocity" to the
larger ports, your remarks on longer duration camshafts notwithstanding.
We'll
see if I ever get around to installing the
45DCOE with larger (36mm) chokes.
If the low end and low mid-range torque
drops off appreciably as the high end picks up, this will tell the tale
in the aforementioned respect.
BTW, my mechanic says the same thing....all else being equal, the alum.
head wll tolerate about 1 full point higher
CR than it's equivalent iron contemporary
on the same octane/timing/plug, etc.
As I said, something has to be responsible
for the "go" I am getting at only 8.3-1.
My PO'd Vizardized 1340 was "faster" but
in terms of useable street torque, my present LC 1293 is far more
"quick", though it's pretty much over by 5k with the
stock SU 1.25 set-up, whereas the PO'd Vizardized 1340 (VP3 with big
valves and
1.5's) running 11.0-1 didn't really get going 'til about 3200 rpm (then
went like hell right to 7K with the 45DCOE using 38mm chokes).
The Datsun 5 speed and choice of diffs
is a godsend with respect to sreet tuning
options along with the alum. head IMHO.
No longer does one need to "build" in terms of expensive "upgraded"
parts to get more power at higher rpms. Now you
can sort of have your cake and eat it, too.
This can save a lot of money
in the long pull. BTW, MiniMania is
marketing the alum. head with the larger
1.4 intake valves as well as the model
with stock valve sizes as well.
Cap'n. Bob
'60 :{)
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