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-   -   One air mixture screw no adjustment. (http://www.hotrodders.com/forum/one-air-mixture-screw-no-adjustment-224317.html)

350 09-23-2012 09:16 PM

One air mixture screw no adjustment.
 
Ok I have a chevy 350 with 305 heads, mild cam, and stock everything else.the carb is a edelbrock 1406. I am sure that I have no vacuum leaks and have just rebuilt the carb due to the same issue I have tried blowing out the air mixture screw checked and double checked everything. I am at my wis end. I am thinking internal crack or blockage idk. But any help would be nice

350 09-23-2012 09:21 PM

Also it will only run smoothly with the screw all the way in. and it whistles when u turn it out a little. However the driver side does like it supposed to can kill it almost by turning it in..

RWENUTS 09-23-2012 10:35 PM

Hook up your vacuum advance to manifold source and turn down your idle on the carb. Your idle transfer slots are exposed too much and you're getting into the power circuit in your carb.

350 09-24-2012 07:54 AM

I have backed off the idle screw as far as I can but I haven't tried it with the vacum on manifold vacum. Wouldn't both screw be non adjustable if it was off the ide circuit. Because I am only having issues out of one side.

RWENUTS 09-24-2012 08:36 AM

I thought the same thing one time about only one side being wacky till I turned the carb over and saw the throttle plates weren't centred the same in the bore on each side. One had the transition slot totally exposed and the other was sitting close to right.

It's a mass produced carb. Never perfect.

350 09-24-2012 08:45 AM

So do you think me putting it on manfoild would help fix it right. I am willing to try it anyway. Thanks for the help. I was out of ideas!

RWENUTS 09-24-2012 11:34 AM

It would get it a lot closer! Try it! Only takes a second to swap the hose on the front of the carb.

350 09-24-2012 11:46 AM

Ok I just got back and wow big difference! Got me pointed the right way. Is their a down side to running off manfolid all the time or do I need to put it back on ported. Cause when I made the switch it went crappy aging. However on manfolid it was smooth and I.have about a half a turn adjustment. Thank u for ur help.

350 09-24-2012 11:49 AM

O one more question when I got on it from a stop it bogged out almost died and came back burned the tires and off it went. But going down the road no prob.? Move the accelerator pump up a hole I think.

RWENUTS 09-24-2012 04:56 PM

Look in the carb with the motor off and stroke the throttle. Look for a strong shot of fuel on each side by the venturi. If not experiment with the rod position till it's better.

350 09-24-2012 05:21 PM

Ok thank u. And would running off manifold vacuum be bad

RWENUTS 09-24-2012 06:00 PM

No. Actually better, smoother running motor. More responsive. Plus you get to tune a slightly rich condition out of your motor by fine
tuning the mixture screws.
The 460 in my truck loves it. Runs like crap if I try to run it on ported.
Just listen for detonation though. It'll sound like a slight knocking at idle. Mine does but goes away when it warms up.If so pull your timing back a couple degrees. Bad detonation sounds like rocks in a tin can. Real hard on pistons.

350 09-24-2012 07:19 PM

Yes sir. Its running a lot better I can't believe that I had hooked up any other way. Thank u so much. I lost my dad last year and I have been stummped ever since he was always the one to help me. He told me he had it rigged to lose power. But I never thought of this. I think if I give it some more base timing it will git rid of my bog taking off and get it close to perfect. Thank u again.

RWENUTS 09-24-2012 07:48 PM

One thing at a time!
Wait on adding more timing and see if the stumble goes away.
You gotta be carefull and listen for detonation.
What's your initial timing at now?

350 09-24-2012 07:52 PM

Not sure to be honest I don't have any timing tape or a any way to set it the timing the little plate that is used to set it is gone. Gotta set it by ear. Bad idea I know. And what should I do first?


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