Roy,
I think you're talking about two separate problems here, which can
contribute to one another. Ignition and carburetion.
The sputtering and backfiring can be a number of things, but look for the
simpler answer first: ignition. If the condition of the ignition system is
unknown or clearly aged, you need to replace more than plugs, points,
condenser and cap. Did you dismantle the distributor when you replaced the
points? You need to make sure the mechanical advance is operating properly,
that the weights and springs are correct, and that distributor shaft is
running true (not worn). Did you replace the plug wires? I don't
understand "...have adjusted the timing as best I can." What is keeping you
from getting the timing essentially dead on?
The high idle is probably carburetion. Make sure the float levels are
correct, the needles and seats (inlet valves) are not leaking. The suction
pistons should drop freely with a slight "thunk". The nozzles must be
properly centered in the throttle bodies, and the tapered needles must not
contact the nozzles. There should be no sign of wear on the needles. Once
running, the air flow through the carbs must be balanced at idle and about
2000 rpm. (Opinions on this vary, but I follow the factory instructions.)
Once you have the air flow balanced, you can balance the fuel flow. I lift
one piston, effectively taking that carb out of service, and adjust the
mixture until I get the best idle I can. Repeat with the other carb. If
everything is right, you should be able to get a stable 500 rpm idle, but I
run about 700-800 rpm.
So, I think you have more work to do before you throw up your hands.
Gary
(219) 322-1923 (evenings and weekends; CST)
----- Original Message -----
From: "Roy Haslett" <hrhaslett@yahoo.com>
To: "Datsun Owners List" <datsun-roadsters@autox.team.net>
Sent: Monday, November 26, 2012 8:56 PM
Subject: [Roadsters] 1600 tuning issues
> Hey All,
> I just replaced my fried points, condensor, cap and rotor...plugs
> too. My 1600 was running poor and backfiring, alot of hesitation too.
> Adjusted valves as well to .017 hot. My problem is its still running
> weird,
> backfiring on deceleration. I have adjusted the timing as best as I can
> and
> acceleration is strong, just the sputtering and backfires when backing
> off...idle is not great either....its high at about 1100 rpm and I can't
> get
> it lower.
> Any suggestions as to tuning?
> Thanks,
> Roy Haslett
> 67 early 1600
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