Author Topic: Stock APT and idal mixture screws setting  (Read 4581 times)

Offline Mr48willys

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Stock APT and idal mixture screws setting
« on: October 22, 2012, 06:04:25 PM »
Hi
    Does anyone know what the stock setting for the APT and the idal mixture screws are. I live in California and need to pass smog. Trying to get it back to stock as close as possible to pass smog. By the way it is on a 1981 Chevy blazer 305. Also if anyone has any tips for smog and the carb I wouk love to know about them

Thanks for any help

Offline Shark Racer

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Re: Stock APT and idal mixture screws setting
« Reply #1 on: October 23, 2012, 11:16:26 AM »
Personally, I'd run the car on a smog dyno and dial in the APT at 25mph on the dyno, then set the idle mixture screws.

Offline Cliff Ruggles

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Re: Stock APT and idal mixture screws setting
« Reply #2 on: October 26, 2012, 09:45:53 AM »
Set the idle mixture screws for best idle quality at the leanest settings.

Set the APT using the "tip-in" procedure in our book.

This will put both idle and part throttle on the edge of lean, and should get it thru emissions....Cliff

Offline Freddiesbuick

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Re: Stock APT and idal mixture screws setting
« Reply #3 on: December 03, 2012, 05:32:19 PM »
Set the APT using the "tip-in" procedure in our book. This will put both idle and part throttle on the edge of lean, and should get it thru emissions....Cliff

What "tip-in procedure"? What book....( I have the Rochester Quadrajet Carburetors book)?  ???

Offline Ethan1

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Re: Stock APT and idal mixture screws setting
« Reply #4 on: December 03, 2012, 06:27:12 PM »
What "tip-in procedure"? What book....( I have the Rochester Quadrajet Carburetors book)?  ???

 From the front of Cliff's website:

 
Ethan

1972 Chevelle

(oo______oo)

Offline Freddiesbuick

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Re: Stock APT and idal mixture screws setting
« Reply #5 on: December 03, 2012, 06:53:20 PM »
From the front of Cliff's website...

Yes I have that book but I don't recall seeing anything about a "tip-in" method for APT. In fact, I spent a lot of time reading chapter 6 about the power piston just looking for that specific info. Perhaps I missed it?  ???

Offline Shark Racer

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Re: Stock APT and idal mixture screws setting
« Reply #6 on: December 04, 2012, 06:39:24 PM »
I believe it's in the performance modifications, it's an inset/sidebar. Look for a picture of a carburetor with a hand held over the primary flaps.

Offline Freddiesbuick

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Re: Stock APT and idle mixture screws setting
« Reply #7 on: December 05, 2012, 05:03:30 AM »
Pg. 99, (chapter 6). Found it! Thanks! ;D