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Author Topic:   Quadrajet idle adjustment
dode
Dirt Forum Champ
Total posts: 613
posted July 21, 2005 12:00 PM  
I would not drill the holes any larger. Is there a problem now with how it idles? Are the boosters dribbling fuel at idle? What sort of response/adjustment do you have on the mixture skrews? The amount of fuel passing thru the skrews as well as what is allowed thru the portion of the transfer slot below the butterflies is what the motor needs for fuel supply in order to idle. Simply put, if too much slot is showing, the motor will idle solely on that fuel and not need any more from the idle mixture skrew circuit...and at that point (sometimes) the main fuel signal starts and booster dribble happens, making it run rough and have poor throttle response.
Are there reasons why you need to idle it below 1100?
Just curious...
I try never to have to drill more than 1/8" holes in a quad primary, or something else isn't set up right. That .050" slot exposure isn't too abnormal, because remember, that slot is not the same width (or length) as in a Holley carb...

KP

dode
Dirt Forum Champ
Total posts: 613
posted July 21, 2005 12:47 PM  
throttle response should be better than any holley out there. what size are your primary jets and rods. the rochester likes it a little fat here.a good starting point is 73 jets with enrichment rods stepped .035/.040 measure the rods with a calliper.

KPLugnut
Dirt Forum Champ
Total posts: 1019
posted July 26, 2005 07:11 PM  
We usually use 72 jets and a .047 rod, but nine finger is correct. Those primaries are usually pretty crisp unless you aren't getting much pump shot, or your boosters are dribbling from pullover or something along those lines...

KP

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