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edelbrock 650cfm, choking under takeoff throttle

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Old Mar 23, 2009 | 10:43 PM
  #1  
snake o8's Avatar
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From: mid west
Car: 1982 pontiac trans am
Engine: 350 ci.
Transmission: TH 350
Axle/Gears: 3.23 stock posi
edelbrock 650cfm, choking under takeoff throttle

when i punch the gas or even half peddle it the engine kinda boggs befor it picks back up.. this just kill responce time.
the accelrator pump seems to be good cuz it starts cold just fine "without choke".

im running a stock 350 200hp factory but now is very tired so im guessing lose of compression to some extent.

im not sure if its the carb or the engine itself anyone have some info?

maybe a smaller carb 550??
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Old Mar 24, 2009 | 08:03 AM
  #2  
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From: Fairview Heights Illinois
Car: 1986 Irocz
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.25:1
Re: edelbrock 650cfm, choking under takeoff throttle

It's not the carb size.
Most carb problems are actually ignition problems.
First check for misfires.
Next check for spark advance.

Your engine may be getting too little advance when you punch it. If you add 10* to your initial timing and the problem starts to go away, then that's a clue. If it stays the same or gets worse, then it points back to the carb.

The lever arm for the accelerator pump can be adjusted, and the squirter nozzle can be changed to a different size. These adjustments change the amount and duration of the pump shot when you hit the gas. The factory setting on the carb should be enough for your engine unless the rubber accel pump plunger is too old and defective - not sealing anymore. Also, if the carb has been taken apart before, the check-valve that sits under the accel pump nozzle could have been lost. This case would cause a problem like you describe.

Try some of this troubleshooting and report back how it goes.
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Old Mar 24, 2009 | 10:08 PM
  #3  
//<86TA>\\'s Avatar
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From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: edelbrock 650cfm, choking under takeoff throttle

my guess is its the carb. I use to use a edelbrock and it was a rear PITA. take it off and place it not so gently in the trash.

the issue i had was the secondary air valve wasn't set right and its not adjustable.

try disconnecting the linkage or the secondaries and see what happens.
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Old Mar 25, 2009 | 04:25 PM
  #4  
snake o8's Avatar
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From: mid west
Car: 1982 pontiac trans am
Engine: 350 ci.
Transmission: TH 350
Axle/Gears: 3.23 stock posi
Re: edelbrock 650cfm, choking under takeoff throttle

i disconnected the secondaries and nothing realy happend other than not being able to feal it when acceleration from cruising speed. 45mph.
still shutters when punched.

i have not checked the timing yet tho.. i havent been able to get it into the shop this week. but the guy who i bought it from did say that the timing marks are messed up so he just timed it the "best he could"... what ever that means.

oh and would the engine being worn out affect this?
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Old Mar 25, 2009 | 09:40 PM
  #5  
//<86TA>\\'s Avatar
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From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: edelbrock 650cfm, choking under takeoff throttle

no the engine being worn would most like not cause this. It seems to be a combination of timing and carb tuning.

Is the dizzy advancing timing properly?


as for what i said before about disconnecting the secondaries. I had my carb tuned pretty well and it would bog if you punched it, then take off. If i disconnected the secondaries and only used the primaries, it would work fine, jut without the extra power of the back 2 barels. I was able to bend and f-with the air valve and got it to work pretty well, but it was never perfect.

Im running a holley 4150 on my new motor and its perfect.
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Old Mar 25, 2009 | 09:49 PM
  #6  
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Car: 1990 Trans Am GTA
Engine: Turbo 305 w/MS2
Transmission: 700R4
Re: edelbrock 650cfm, choking under takeoff throttle

Originally Posted by snake o8
maybe a smaller carb 550??
Your carb is fine in size, it just needs to be tuned. Was going to explain the procedure, but sometimes it's easier if you visually see the process, as opposed to reading....

These should help a little....;

http://www.youtube.com/watch?v=xspfeMJO3O8
http://www.youtube.com/watch?v=ADw0KKwSkV4
http://www.youtube.com/watch?v=EEeKYZS-Stg
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Old Mar 26, 2009 | 01:02 AM
  #7  
snake o8's Avatar
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From: mid west
Car: 1982 pontiac trans am
Engine: 350 ci.
Transmission: TH 350
Axle/Gears: 3.23 stock posi
Re: edelbrock 650cfm, choking under takeoff throttle

thanks for the helpfull info. i wont be able to change the timing or anything els untill this weekend, as soon as i do ill report back and tell you if it fixed the problem.
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Old Mar 26, 2009 | 06:54 AM
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From: NYC / Jersey
Car: 1990 Trans Am GTA
Engine: Turbo 305 w/MS2
Transmission: 700R4
Re: edelbrock 650cfm, choking under takeoff throttle

Originally Posted by snake o8
.... as soon as i do ill report back and tell you if it fixed the problem.
Good deal....
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Old Mar 31, 2009 | 01:25 PM
  #9  
snake o8's Avatar
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From: mid west
Car: 1982 pontiac trans am
Engine: 350 ci.
Transmission: TH 350
Axle/Gears: 3.23 stock posi
Re: edelbrock 650cfm, choking under takeoff throttle

the weights and springs in the distributor were fried, the bushings the weights ride on were worn out so the post it pivits on were almost worn to breaking off, and the weights round circle is now a long oval.

i suspect that this is one of my main problems with acceleration.
i dont have a new distributor yet but im going to get one soon any ideas what would be the best choice or reasonable money?
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