<VV> ignition knocking on 66 Corsa Turbo

[FrankCB at aol.com]

Guus and Bob,
 
     You can check the retard that will be produced by  the pressure retard 
unit by disconnecting the connection between the retard unit  and the 
engine and plugging the line to the engine.  Then attach a  hand-held unit (like 
a Mighty Vac) that provides a measureable amount of low  pressure to the 
retard unit on the distributor.  Run the engine at idle and  use a timing light 
to see exactly how much retard you get with varying  amounts of pressure.  
This will also show if you are getting ANY retard at  all.  
     When I bought my 65 180 Corsa it came with a  vacuum advance unit 
instead of a pressure retard.  Luckily for me on the  drive home the vacuum 
advance had a leak in it so it provided NO vacuum advance  as well as NO 
pressure retard.  Instead of replacing the incorrect (and  failed) vacuum advance 
with the correct pressure retard, I decided to install  a WORKING vacuum 
advance (from a non-turbo Corvair) and use an electronic  knock sensor/retard 
unit to provide retard when it was needed.  That way I  had vacuum advance in 
UNboosted operation just like any other Corvair  and still had retard 
available for when the engine got into boost.  For  more details read my chapter 
on Turbocharging in the Corvair BASICS Manual  available from CORSA.
Good luck and let us know how it goes,
Frank "boost IS the substitute for cubic inches (or CCs)"  Burkhard
 
 
In a message dated 3/25/2012 4:17:09 P.M. Eastern Daylight Time,  
BobHelt at aol.com writes:


You  can't check the retard unit that way (via my procedures). It requires  
 
actual pressure (engine under load) to activate. Also you should know that  
the  Chev specs for the retard units are grossly incorrect. Actual  retard 
pretty much  follows boost pressure....meaning max retard at  max boost, 
and min 
at min.

let us know if you need more help or  information.
Regards,
Bob Helt


Regards,

Guus de   Haan