[1157 motor head]

i have a 67 GTO with a 400 H.O. and 4 spd. trans. . i am the second owner of this car and have owned it since 1989 . i found out the other night that the vacuum advance port on the carb. is drawing 10 inches of vacumm at 700 rpm idle speed . this is the port on the lower left side of the carb up front . i believe there should be no vacuum on this port at idle speed . does anyone out there have the same problem with this year carb. and engine setup ? what could i possibly be missing ?

Jim

[1157 motor head]

Oh and by the way . this is a number matching 400 to quadra jet set up

thanks Jim

[cuz68]

I would hook it up to the back of the carb.

[1157 motor head]

the correct instalation is to the front of the carb via a steel tubing from the distributor . this was the factory set up . with that in mind i assume there was not any vacuum at idle using this port .

[Kenth]

1967 Quadrajets is the only vintage that have manifold vacuum in the very same port where the later Q-jets have ported vacuum.
1967 Q-jets also don´t have idle bypass air.

[1157 motor head]

Kenth

so what do guys do for the vacuum advance ? the vacuum is pulling up the advance at idle rpm .

Jim

[Kenth]

Jim, that´s the way it´s supposed to be on most 1967 and earlier vehicles, before HC emissions had to be reduced.

[1157 motor head]

thanks for the input guys .
in the shop manual for 67 it tells you that the car is a manifold vacuum advance, and to time the car with the vacuum advance disconected . after setting timing reconect the vacuum advance and adjust idle.

Jim