John,
Good explanation. I did not know that. However, the '69 U20 motor in
my '66 1600 runs fine without the return line. Of course, I have taken great
pains to make sure the fuel line from the pump to the carbs is routed in areas
as cool as possible.
One thing I find interesting. My '66 U20 seems to be
cooler under the hood than my '67-1/2 U20 Solex. Man, the '67 get's hot! Hot
enough that the hood prop rod can be painful. The engine itself runs cool
enough -- never seen it over 200 even stopped in traffic in downtown LA. And
the '67-1/2 is hard to start if it sits for a while after getting hot. Figure
it is vapor lock, so I generally open the hood, as long as I can keep an eye
on it.
Gary
________________________________
From: John F Sandhoff
<sandhoff@csus.edu>
To: datsun-roadsters@autox.team.net
Sent: Friday, August
28, 2009 10:55:54 AM
Subject: [Roadsters] Return fuel line (was: when I got
stranded by the 2000...)
It was suggested:
> how about just lose the return
line? Remove the fuel return valve,
> change the inlet fitting to the rear
carb and cap off the line back to
> the tank.
Not trying to start any flames,
and with all due respect, but the return
line is not some smog gizmo but is
actually something that you want
in place. Nissan added it to reduce the
possibility of vapor locking on
hot days. It allows the fuel to 'keep moving',
reducing the risk of the
fuel vaporizing inside the fuel line before the carb
and starving the
engine.
One point of note is that the return valve (the
gadget mounted on the
rear carb) limits how much fuel goes back to the tank,
and on very
rare occasions has been reported to stick open and allow too much
fuel to bypass the carbs.
On the 1970 ONLY model, there are additional
separator tanks
and vent plumbing and air flow solenoids and such that are
part
of the vapor recovery efforts. Overall its presence doesn't affect
performance and may marginally make the cars cleaner, so IMHO
there's nothing
to gain by ripping it out...
-- John
John F Sandhoff sandhoff@csus.edu
Sacramento, CA
p.s. I didn't think a '66 model year vehicle had any smog
equipment,
save for the PCV system (which again IMHO is a good thing to have)
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