AFB on 390 stumble
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AFB on 390 stumble
I put on a new Carter AFB 9755 (similar to a 1407 Edelbrock) and have a stumble just off idle, but only under load.
I wonder if I should switch power springs? The accellerator pump is already on the top hole.
I wonder if I should switch power springs? The accellerator pump is already on the top hole.
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AFB on 390 stumble
Yep, put stiffer springs on the metering rods (thus making them lift under less vacuum loss). That should cure it. Also, you might want to check the float and make sure it's set up properly.
I did the same thing with the edelbrock on my '69 390 GT and it cured it right up and then some. I assume you've already checked out your ignition system?
I did the same thing with the edelbrock on my '69 390 GT and it cured it right up and then some. I assume you've already checked out your ignition system?
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AFB on 390 stumble
I replaced the springs with the black ones. It pulls tough after the stumble, but it stumbles off idle.
Do you think I should put the pump in the middle hole? It's on the inside hole now. Where do you have yours?
Do you think I should put the pump in the middle hole? It's on the inside hole now. Where do you have yours?
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AFB on 390 stumble
I have mine on the middle hole. Now that I think about it, I am not sure which way you go to increase accelerator pump output. My guess is the closer you move toward the outside, the more sensitive it is to the throttle. Are you getting the stumble at a certain rpm or at a certain throttle setting?
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AFB on 390 stumble
It was on the top hole, but I switched to the center one and found it helped but didn't cure it. It wasn't enough fuel.
I got to looking and found that the lower lever on the throttle linkage and the link were set kinda short, so I bent them a little. The stumble appears to be gone, at least for now.
I also found that when I stomped it this morning and it died, that the secondary lockout tang was improperly set up. The link allowed the tang to overcenter and lock in when the choke was fully open. If you pushed a little harder the secondaries would partially open and at the same time close the choke. I bent that link too and it seems to be OK.
So much for out of the box performance.
I got to looking and found that the lower lever on the throttle linkage and the link were set kinda short, so I bent them a little. The stumble appears to be gone, at least for now.
I also found that when I stomped it this morning and it died, that the secondary lockout tang was improperly set up. The link allowed the tang to overcenter and lock in when the choke was fully open. If you pushed a little harder the secondaries would partially open and at the same time close the choke. I bent that link too and it seems to be OK.
So much for out of the box performance.
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bshackelford711
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
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Jul 1, 2005 01:40 PM
