If it were me, I'd worry a lot more about advance at speed than at idle.
That's where real dammage gets done. Take a tip from porsche factory, and
set the ignition advance where all of the advance should be in, and let
idle be where it comes out. That means getting an advance curve
somewhere - the Bentley manual probably has one.
If (this would be typical, but not necessarily correct for your car) your
total advance is in at 3500 rpm, and is to be 300, then you would need to
mark the pulley so that you can read 300 (which you typically can't,
because most cars are read at idle), rev up the engine to 3500rpm (with
the vacuum line off), and adjust the distributor so that it shows the
300. I do realize that this isn't easy with a british car, but I think
the '76 Midget would be easier than an early B (since the early cars read
from the bottom of the engine, and later cars read from the top).
You can't really adjust the amount of vacuum advance anyhow, so you don't
have to worry about that.
Phil Bates
> Hello Troopers,
> I have a '76 Midget with the 1500cc engine. This
> car has [now] has the 45D4 distributor and 'should'
> be USA (non-California) spec. Any of you now the
> profile of the vacuum advance module? In '76 was
> it really an 'advance' module? That is the way
> it is oriented on the dictributor.
>
> The vacuum port on the DGV carb is set up like the
> older SUs. That is, the throttle plate covers
> the vacuum opening in the throat until the
> throttle is lifted off of it's rest. At that time
> the vacuum rises inversly proportional to the
> throttle opening while accelerating.
>
> Where am I going with this? I need is to design
> the 'best' static or low engine speed timing for
> general street use. The manuals vary between 10
> degrees BTDC to 2 degrees ATDC. These numbers
> represent both emissions-related settings AND the
> way the vacuum is ported to the distributor.
>
> I'd like to hear your opinions please.
>
> Rick
> '76 Midget, not quite as
delivered...
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