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Chapter 18 11/1/01 Winter is nipping at
my heals here in Minnesota, and with that, development on the car will need
to be in the workshop with occasional forrays onto the streets, which will
soon be covered with a thin coating of black ice (auto exhaust which has
frozen on the asphalt....). Did pick up a series of jets and needles
for the carb to make it run richer yet. Found an old article in HOT ROD
about AFB carbs which states that for blown applications, they were going as
rich as 0.150 inch in some cases, and drilling out the idle bleed jets.
Did decide that for the winter, I need a hood, and after some measuring determined that the
air-cleaner will fit under the stock hood, but not the "Air Hat". I am not
satisfied with the side entry hats which are rather simple construction, and
way too expensive for what they do. I set up a manometer using a loop of
tubing and some old brake fluid. I started to fabricate an air hat out of plastic pipe, and did some
tests on the air pressure across the "carb-mouth" end. I
hooked up a leaf blower for
some pressure. It is amazing what happens to air when you point it at a
wall...... Anyway, I tried various restrictions and wound up with a sieve arrangement inspired by
something I saw in a Dick Datson publication. The plastic sieve is about 3/8 inch
thick. The holes each have an inlet which is counter-sunk, like a small
venturi. My tests
showed much less variation in air pressure across the mouth, though I realize
that there is some restriction thru the sieve. I am hoping that the
trade-off will be that the 'straightened' air will create less weirdness as
it enters the carb, with more predictable results thru-out various pressure
situations. This hat will also fit under the hood, and so far has cost
me $2.49 for the 5 inch plastic pipe and a few bucks for some epoxy putty
(great stuff!). Haven't made the top of the hat yet (have been testing
with duct tape), but expect it will be rounded on the inside. Might use
a piece of an old motorcycle headlight for this. For now, I've got a
piece of Plexiglas fit over
the top which could be
carved on the inside to give better dispersion, or maybe I will build up that
surface with Lego blocks in some different patterns to see what
happens! I will be adding fittings for the blow-off valve, the fuel
pump boost reference and the boost gauge #1 right on the air hat, maybe with
some angle cut to the part protruding into the air stream to semi-negate the
low pressure of a right angle. (Any thoughts on this appreciated).
Rebuilt the defroster and
heater blower which are 6 volts, but seem to work great, without overheating
at 12 volts. Needed to modify brackets on blower to still fit under hood
despite everything else I added there.... |
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