Hmmm, I musta missed the original post. Ah well, I've jumped into the
middle before.
>
> >The car runs great under load or at high revs. But let it idle down,
> >and it will stumble. It doesn't die, but it... well, it misfires.
>
> > SO I bought the Crane electronic
> >ignition module to alleviate this problem. Car ran just the same.
> >Actually the car started up and ran GREAT the first time. I was
> >amazed. After shutting it down, cleaning up, etc, the car began to
> >run the way it always did.
Here's an incomplete off-the-top list of possible problems:
Torn carb diaphragm(s)
maladjusted carb thermo compensators
mixture excessively rich or lean for other reasons
emission plumbing routed wrong
mechanical advance stuck in the full advanced position
Plug wires too long, chafing on the hood (runs *great* with the hood open :)
Breaker plate locator (part of retard can) broken.
Tight valve(s)
>
> >I can't find any air leaks. (that doesn't mean their aren't any, but
> >I can't find any!) If it does have a leak somewhere, it's not really
> >bad. I'm dubious on how well the vacuum retard is working. You know,
> >I pull the hose and nothing really happens.
If the idle doesn't jump up a bunch when pulling the hose off, then something
is wrong. Either the vacuum can is broken physically, or the diaphragm is
ruptured, or the vacuum hose is routed wrong or plugged. The only one of
these possibles that would *really* have adverse affects of the running is
a physically broken unit. Pop the cap off, grab ahold of the plate that the
points/condenser... ummm. *used* to be mounted to, and try to twist it in
the horiz. plane. If it moves easily more than a (very) few degrees, then
look down inside on the side of the vacuum can. There is a spring from the
can that hooks to a post on the plate. If this breaks (they do sometimes),
you're vacuum can will not have any effect, and the timing will be of the
infinately (ramdomly) variable type. :>
>
> On the other hand supposedly the retard was added to reduce
> emmisions. Does it ever kick in at non-idle speeds? (maybe when closing the
> throttle at revs?) How does it reduce emmisions? Is it reasonable to just
> disconnect it, since people have said that it hurts performance and fuel
> economy?
>
> Randell Jesup ('70 TR6, with vacuum advance AND retard).
The vacuum retard is kicked in any time manifold vacuum exists. This means
the only time it's out is when you have the pedal matted. So it doesn't
affect full throttle power, and Truimph can still publish high horsepower
numbers. But it affects every other throttle position. The place it hurts
the most is part throttle cruising; especially slight load variations.
If you live in a hilly area, try popping the hose off and pluggin it.
You will notice the difference. And.... the CO emissions may be too high
to pass a sniffer test.
Randy
randy@taylor.wyvern.com
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