Martin Gonzales writes:
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After having the head re-done and milled to a 9.5:1 compression and the
various valve components replaced, I am having a problem with dieseling.
I have set various settings on the timing, breaker gap, sparkplug wires,
choke adjusted, tried various carb damper settings, and the following:
a) disconnected the red wire on anti-run on valve, plugged small orifice
on
the valve and the small orifice on the intake manifold. Prior to the head
being done, this method worked fine without dieseling.
b) set the emissions hoses to a pre-73 setting that is to say, using two
orifices on the carbon canister, plugging the third, disconnected the
anti-run on valve, plugged the emission orifices on the carbs,
c) and a couple of various other things with the emission hoses.
Any ideas as to the cause of the dieseling?
Martin Gonzales
73 TR6
San Jose, CA
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Martin;
Let me get this straight. You disconnected the anti run-on valve
and now you are having problems with the engine running on?
The reason your car is dieseling (running on) is due to spontaneous
combustion of the gas-air mixture from the increased compression.
The anti run-on system prevents dieseling by applying engine vacuum
to the top side of the float bowl chamber in the carbs when the engine
is shut off. Here's how it works:
When the ignition switch is switched to the off position a special
terminal on the switch puts +12 volts on one side of the anti run-on
valve solenoid. The other side of the solenoid is connected to the
three terminal oil pressure switch. The valve will remain activated
as long as there is oil pressure.
While activated, the valve will connect the vacuum in the intake
manifold to the charcoal canister and consequently to the float
chambers via hoses connected to the special fittings provided
therefore. The net result is the gasoline is "sucked" away from the
metering jets starving the enging and thus preventing dieseling.
I recommend reconnecting the anti run-on system.
Dave Massey
St. Louis, MO
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