The Thermoquad IS a vacuum secondary. Meaning that the top flap thing stays
closed until there is sufficient atmospheric pressure differential on the
top and bottom side of it to open it up. This is supposed to decrese the
bog effect of opening the secondaries at low rpm. There is another vacuum
conponent in that the vacuum pot on the right side of the carb will hold the
secondaries closed if there is very low vacuum in the intake (meaning there
is more open throttle and there is rpm to soak it up)
Not a very good explanation but it might help.
BTW, some Thermoquads run great. I have three that do so they're not all
bad.
----- Original Message -----
From: "James" <nyb@xxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Sunday, May 04, 2003 2:12 AM
Subject: Re: IML: Pop goes the carburettor
76 is indeed a Thermocrap. I'm pretty sure it's a vacuum secondary
carb, but I have seen them open before while in park. Whether they are
supposed to or not, I don't know.
Brian Collinsworth wrote:
Back to the Home of the Forward Look Network