Rochester Idle Mixture Screws
Thread Starter
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
Rochester Idle Mixture Screws
I am frequently adjusting my idle mixture screws. I make an adjustment then in no time the screws have moved and I have to re-adjust. Is there any reason that the screws are slipping? Is something on the carb missing or should I use some sort of lock tight on the threads?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Right! Those springs prevent the screws from vibrating loose. If there are no springs on the threaded shaft of those idle screws, they will loosen. You should be able to buy some 'general purpose' springs that will work at any hardware store; they are not "flimsy" and have wire diameter of about .030" and are about 1/2" long.
Thread Starter
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
Once I make the adjustment the quality is fine. It will run fine for a few days then it becomes noticeable that the idle quality is changing. I noticed how bad it is today because I decided to warm it up in the garage....makes me feel like spring is here soon
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Racer
Joined: Aug 2007
Posts: 267
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From: Springdale Arkansas
is there any fuel dripping from the primary boosters?
is there alot of play in the primary throttle shaft?
Reaosn being if there is air coming from some place it's not suppose to be you may be compensating for this by having to back out so far on the idle adjustment screws that it relieves the retaining tension of the springs. Genreally if the idle circuit has not been resized the adjustment screws end up about halfway out on a healthy engine.
FWIW,, Jimbo
is there alot of play in the primary throttle shaft?
Reaosn being if there is air coming from some place it's not suppose to be you may be compensating for this by having to back out so far on the idle adjustment screws that it relieves the retaining tension of the springs. Genreally if the idle circuit has not been resized the adjustment screws end up about halfway out on a healthy engine.
FWIW,, Jimbo
Last edited by jimboscarbs; Feb 5, 2011 at 02:05 PM.
Thread Starter
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
Normally I only need to seat the screws then turn them back about 1 turn and the car idles fine. This morning I had to turn them more than three complete turns to get them to seat again. That is how far out it went in such a short time.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I would think that if you know where the screws like to be, (one turn out) just back them out about 5 turns or so, a drop of loctite, and screw it back in. Done and done.
If anyone can think of why this might be a dumb idea, hurry up and let us know, before he tries it.
Scott
If anyone can think of why this might be a dumb idea, hurry up and let us know, before he tries it.
Scott
