Errol you are correct here, but I'll just expand the idea a bit more.
The vac control unit is a very similar arrangement to the British solution
to the same problem (MG?) the valve just expels the manifold vac to atmo at
ign off. To use the other way some 180B's with A/cond had an adjustable fast
idle control on the accelerator rod - these are great for setting the normal
engine idle with SU's and when the ignition is turned off the control slams
the throttle shut - no air, no run on. Both of these methods also work well
with 32/36 or 38mm downdraft webers that are also prone to run-on. There is
another way to control electrical run-on as the ignition system on the 510
can feed power to the coil with the ignition switch on but the alternator is
still charging - you can try this with a multimeter on the coil at 2000rpm
kill the ignition - coil is still getting power till around 400 rpm which is
great for causing run-on. You put an electronic gismo on the coil wire that
acts as a shunt when the key is turned off. I think Dick Smith has these
things, they are actually designed to stop electronic fuel pumps if the
engine stalls.
regards
Terry
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Errol Smith
Sent: Friday, 17 November 2000 6:17 PM
To: [EMAIL PROTECTED]
Subject: Re: L20b advice needed
Craig,
I thought the late 180B control was an air bleed to lean of the mixture and
hopefully prevent run on but I am open to correction here.
Craig Haywards engine runs smoothly!!! with no ignition on. Some one had
actually put a step up idle solenoid X auto trans model on the throttle
shaft to allow idle with ignition running. This would allow the throttle
plate to fully close when the ignition was turned off.
This is the only way to stop it short of a clutched stall!
Very cold plugs (NGK B10EGV) Platinum race plugs, actually improved the
performance. It also made the engine run smoother with less pinging. The
plugs do not foul at all. I guess due to the increased combustion
temperatures. This engine has 210 PSI comp per cylinder.
Cheers
Feral Errol
WWW.Datrats.com.au
----------
From: Craig Overend <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: Re: L20b advice needed
Date: Monday, November 13, 2000 18:50
Errol the run-on you described is likely due to the engine still sucking
fuel into the combustion chamber when there is enough compression and
heat or possibly a hotspot/hot plugs to combust the fuel creating a
rough idle with ignition off. What carby did it run?
I know of an L20B with almost flattops that has this same problem with
SU's, that runs too much CR. My 910 Manual shows the late model SU's had
a solenoid to the fuel bowl breather that closes and stops fuel being
sucked in when ignition is off. I think the late stock L18 carby also
has such a device.
Craig.
Errol Smith wrote:
>
> Arty,
> For a streeter I would keep the comp to 9:1 on stocky pistons or you may
> have problems with detonation unless you run Premium fuels.
> I had a look at Daniel Haywards 200B running flat tops (cylinder
pressures
> 210 Psi on comp test!!!!) and the engine ran quite happily with the
> ignition turned off!
> Cheers
> Feral Errol
> WWW.Datrats.com.au
>
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