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Re: [Mgs] Timing discussion

To: "Richard Lindsay" <richardolindsay@gmail.com>, <mgs@autox.team.net>
Subject: Re: [Mgs] Timing discussion
From: PaulHunt73 via Mgs <mgs@autox.team.net>
Date: Wed, 24 Apr 2019 14:36:16 +0100 CSo5JXoJxmXaUvrhjP0xzRxhA9Lfi+EnHcqQc78J89c40PnW7G1BCnZfkMGC/weOgwdOZHrgz4n9IlWQKkBhA09anamCFyPeycQ=
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----- Original Message -----=20
  > Are you sure that isn't vacuum retard?


    Yea, I wrestled with that for ages when restoring my car. The early =
Biturbo turbos blow through the carburetor, which is enclosed in the =
plenum. When boost comes up, vacuum advance fails so the other capsule =
takes over. Its a nasty, complex system with flow restrictors in various =
vacum/pressure lines to retard reaction time. It almost destroyed my =
love of dynamic systems! :-P

  Ah of course - boost kills 'vacuum' advance, so 'pressure' advance =
takes over.

  ... When preignition or pinking occurs, the computer modulates the =
waste gates to reduce the boost.

  For a long time I messed around trying to get a 'knock-sensing retard' =
system onto the MGB, but the engine is so noisy the knock sensor was =
triggering all the time!  Early BL computer controlled systems used that =
instead of (or maybe as well as) fixed maps, suddenly tread on the =
throttle to pull away and you could hear it pink like billy-oh, then =
rapidly reduce as the system retarded.  Had it worked it would have =
largely taken the place of centrifugal and vacuum advance, but never =
mind.

  Paul.
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<META name=3DGENERATOR content=3D"MSHTML 8.00.6001.23588">
<STYLE></STYLE>
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<BODY bgColor=3D#ffffff>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: =
black">&gt; Are=20
  you sure that isn't vacuum retard?</DIV>
  <DIV dir=3Dauto>
  <DIV dir=3Dauto class=3Dgmail_quote>
  <DIV dir=3Dltr class=3Dgmail_attr>
  <DIV dir=3Dauto><FONT size=3D2></FONT><BR></DIV>
  <DIV dir=3Dauto>&nbsp; Yea, I wrestled with that for ages when =
restoring my car.=20
  The early Biturbo turbos blow through the carburetor, which is =
enclosed in the=20
  plenum. When boost comes up, vacuum advance fails so the other capsule =
takes=20
  over. Its a nasty, complex system with flow restrictors in various=20
  vacum/pressure lines to retard reaction time. It almost destroyed my =
love of=20
  dynamic systems! :-P</DIV><FONT size=3D2></FONT></DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT size=3D2></FONT>&nbsp;</DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT size=3D2>Ah of course - boost =
kills 'vacuum'=20
  advance, so 'pressure' advance takes over.</FONT></DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT size=3D2></FONT>&nbsp;</DIV>
  <DIV dir=3Dltr class=3Dgmail_attr>... When preignition or pinking =
occurs, the=20
  computer modulates the waste gates to reduce the boost.</DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT size=3D2></FONT>&nbsp;</DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT size=3D2>For a long time I =
messed around=20
  trying to get a 'knock-sensing retard' system onto the MGB, but the =
engine is=20
  so noisy the knock sensor was triggering all the time!&nbsp; Early BL =
computer=20
  controlled systems used that instead of (or maybe as well as) fixed =
maps,=20
  suddenly tread on the throttle to pull away and you could hear it pink =
like=20
  billy-oh, then rapidly reduce as the system retarded.&nbsp; Had it =
worked it=20
  would have largely taken the place of centrifugal and vacuum advance, =
but=20
  never mind.</FONT></DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT size=3D2></FONT>&nbsp;</DIV>
  <DIV dir=3Dltr class=3Dgmail_attr><FONT=20
size=3D2>Paul.</FONT></DIV></DIV></DIV></BLOCKQUOTE></BODY></HTML>

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