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Author Topic:   quadrajet modification questions
posted November 04, 2003 10:41 AM
I bought the book KP suggested , Rochester
Carbs, by Doug Roe. I have a couple of questions about the 4 barrel, non electric

I'm trying to locate the asperator channel
in the primary ventury and cannot seem to find it. Can anyone tell me exactly where it's at? Is it plumbed into the idle channels or the main fuel well that feeds the
discharge nossel?

In adjusting the secondaries to open earlier,
I have the model that requires "the hole for the rod to the primary throttles must be relocated downward toward the secondary throttle shaft." I don't understand what hole is to be relocated? Connecting the primary throttle shaft to the secondary throttle shaft is a rod. The rod is attached through a hole on both the primary and secondary shaft. Which hole is it, the one on the primaries or secondaries?

posted November 04, 2003 11:49 AM
The hole they're talking about is the hole that the rod goes thru in the primary linkage. Timing the secondary opening point really gains throttle response, but you have to make sure you don't over-extend or over-open the secondaries as going too far past verticle kills flow (and power).
I'm not sure what you mean by the asperator channel.
Altering the spring loaded secondary linkage by cutting the slot for the spring in the secondary throtle shaft (as the book states) also is needed to get the secondaries coming in sooner than 3/4 throttle.

Hope that helps.

posted November 04, 2003 02:58 PM

posted November 04, 2003 03:26 PM
thanks for the reply kp.
about the asperator channel, on page 10 of that book, 2nd paragraph it says ...

the venturi controls the main metering system by governing the fuel discharged into the point of lowest pressure or greatest vaccum. this minimum pressure point supplies a signal to the main metering system. the pressure drop signal to the main and power systems via an asperator channel. the channel is plumbed from the point of greatest depression in the boost venturi on an upward angle to the vertical fuel pickup. the channel in turn get fuel from the main and power systems.

is there a real physical channel or are they
talking about the path fuel travels from
main fuel well because of the vaccum?

I cannot seem to locate the physical channel.

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