<VV> Frank Gets Corrected Re: Vacuum Advance? Re: custom distributor curve?

[FrankCB at aol.com]

Bob,
    I was just "checking" to see if you were paying  attention!!!<GGGG>  If 
you believe THAT I have a bridge in  Brooklyn I'd like to sell you!<GGG>
    Seriously, YOU ARE CORRECT,  Bob.  With the stock turbo setup, if you 
are getting  boost at ANY rpm then it will retard the timing to LESS than the 
 base timing which is supposed to be 24 deg. BTDC (for 65 & 66 180  
engines).  However, if you are OVER 4000 rpm, then you'll be getting some  
MECHANICAL advance as well which will increase the timing ABOVE 24 deg. to be  
reduced by whatever the pressure retard subtracts.  So below 4000 rpm, any  boost 
will RETARD the timing.  Above 4000 rpm the mechanical advance will  
INCREASE the timing while at the SAME time, any boost will RETARD the  timing.   I 
hope I have this right now.<GGGG>
    I guess you guys driving out West can get boost at  2000 rpm much more 
easily than those of us driving in the "cityfied" areas of  the NorthEast.
    Thanks for the correction, Bob
Frank "the other one" Burkhard
Boonton, NJ.
    
 
 
In a message dated 2/22/2013 9:14:43 P.M. Eastern Standard Time,  
BobHelt at aol.com writes:

NO NO! The retard will work at low rpms as long as there is minimal  boost. 
Boost starts around 2000rpm. Frank, look at the 65 Shop Manual  page 6Y-16 
fig 11. Pressure retard retards spark to below static  setting.
 
Regards,
Bob Helt
 
 
In a message dated 2/22/2013 4:56:03 P.M. US Mountain Standard Time,  
robertkhenry at bellsouth.net writes:

Consider the completely stock turbo Corvair that  comes with  NO vacuum
advance and only has pressure ignition  RETARD that works  at rpms ABOVE 
4000
(for the 1965 and 66  models).  Driving  these cars in traffic means using a
CONSTANT FIXED  ignition timing  (24 degrees BTDC) until you get above 4000
rpm AND  achieve some  boost