Make sure your carburation is set for the proper mixture and then set
the timing "by ear" for the gas you are using. By this I mean retard it
to minimal (or no) pinging when you go up a moderate hill in 3rd with
the pedal to the floor at low speed (i.e. lug the engine a bit). Use
avgas for racing, and auto gas for street use for maximum performance,
economy, and convenience.
Running on after shutdown is caused by two things: (1) The fuel supply
from the carbs is not cut off (like in modern cars) when the ignition is
off, so gas can be sucked in and "detonated" by (2) hot spots in the
combustion chamber, particularly the "point" original head castings had
between the valves.
The "release the clutch in gear after shutdown" is the proper way to
stop the run on, and timing by ear to maximize performance for the gas
available (or that I'm willing to pay for) has worked for me for the
last 25 years.
As for the squawking racing clutch, it's designed to be engaged at 4000+
RPM, it's just complaining about street use!
Eric wrote:
>
> A simple question or two ;-)
>
> Is it damn inevitable that flat-top pistons and a ported/polished head
> will lead to run-on (dieseling)? Or pinging/pinking under load unless
> high octane fuel is used?
>
> Without killing the performance of the vehicle (I paid a lot of money
> for that performance) I am finding it really hard to resolve either of
> these issues, but both are manageable using AVGAS.
>
> I am also now getting a strange 'squawk' sound from my ceramic/kevlar
> button clutch just as I take off smoothly from a standing start (you
> don't hear a thing under race-type start conditions).
>
> Yes, I never expected everything to go smoothly when I messed around
> with such a lovely little driver like this, but at least she goes fast
> now.
>
Stuart MacMillan
Seattle
'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)
Personal mechanic for:
'70 MGB GT (Daughter's)
Assisting on Restoration (and spending OPM):
'72 MGB GT (Was daughter's, now son's)
'64 MGB (Son's)
Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT
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