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Discussion Starter · #1 ·
I'm hopeing that you guys can give me some help, cause I'm fixin to blow my brains out trying to figure this out:-HS. The problem is a lean stumble that will not go away. Its a AED 750 HO on a 350 with a decent roller cam. I started with 72,78 jets with 31 31 squirters. Went all the way up to 47 45 squirters and it will not go away, as long as its above about 3000rpms it seems to do okay but anything below it falls on face and then picks right back up sometimes its bad enough to pop back through carb. Have changed pump cams taken powervalve out and squared jets but still no help. Also have wideband in car to back up what car acts like. Have pulled metering blocks to check everything looks okay. any help would be greatly appreciated. thanks
 

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What about the pump shot ? Are you running the 50cc pump?

When you squared the jets after removing the PV, what jets did you run then?
 

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Before you go any farther, are you running any advance in the distributor, mechanical or vacuum? Once you get into a moderate cam you can plan on locking the timing to where it runs best, usually 37 to 41 on standard 23˚ heads. Vortecs a little less. Any curve can make it sluggish.
 

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Before you go any farther, are you running any advance in the distributor, mechanical or vacuum? Once you get into a moderate cam you can plan on locking the timing to where it runs best, usually 37 to 41 on standard 23˚ heads. Vortecs a little less. Any curve can make it sluggish.
X's2
 

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Discussion Starter · #6 ·
Jets are now 78 square 30 cc pump timing locked out at 40. Have not done anything to airbleeds. Pulled this carb off of buddys 408 LS1 and it worked fine on his. I thought about changing to 50cc pump but that just seems exccesive for a 350?
 

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What pump is in your buddy's carb ?
Don't base pump size off cubic inches. It wants what it wants. The larger squirters usually need more fuel.

Are the air bleeds in your carb clear - no obstructions ?
 

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Discussion Starter · #8 ·
This is the carb that came off of his motor. I understand that larger squirters need a bigger pump sometimes but my point is why the hell would an average 350 need that much fuel it just seems wrong, checked air bleeds they looked okay.
 

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your converter is too tight ..
are you leaving off the foot break ..'
if the converter is to tight to get the motor up in rpms it will stumble no matter how much fuel you have ..
 

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Discussion Starter · #10 ·
Converter flashes a 4000 on transbrake with no twostep pill. But the motor makes no torque what so ever so it doesn't footbrake all that high but it leaves like bat out of hell on the gas.
 

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Have you check the pump arm adjustments? Make shure they are getting full travel... Sometimes they do not come back far enough and bottom out when you hit it so you're not getting a full shot.

Have you played with differnt pump cams at all? Some of the pump cams are on the lame side I've seeen the right cam make a huge difference.
 

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Discussion Starter · #14 ·
I have checked the pump arms they seem good. I have changed pump cams, gone to more aggressive pump cams with no change. Carb has jet extensions but, the carb not only does this when you leave on it but it does it in park as well. I don't have my old carb anymore but my last carb did not have this problem and on my buddys 408 it didn't do this.
 

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Could also br the little check valve in the acc. pump looks kinda like a bb. A little peice of casting can stop it from making a good seal then lots of your fuel just goes back into the bowl when you hit it...
 

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Call AED up , ask for John Dickey, he is the main tech and owner of the company. If you ask me you went way too far in your squirters. Anything over 35 you need the hollow acclerater pump screw. The carb came stock with 31's in the front and rear correct? Increasing the squirter size did it get any better?

Dave
 

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Discussion Starter · #19 ·
Ray don't give me any ideas I still got all of it. I will check the valve inside of pump. I know it shouldn't need squirters that big that was the point in posting all this. The squirters did improve to extent it does have hollow pump screws but at this point I've maxed out the 30cc pumps it needs 50cc with anything over prob 37 as well but I was just trying to get by until I could figure out whats really wrong.
 
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