Author Topic: throttle plate sticking open when slightly revved  (Read 6962 times)

Offline txchainsawgogi

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throttle plate sticking open when slightly revved
« on: February 05, 2012, 12:00:51 pm »
BRAND new qjet on a 78 350 5.7l. it wasnt doing this when i first bolted it on, for the first day it was literally an instant improvement over how the truck used to run/idle/respond.

but as of lastnight the throttle gets stuck. it was partially the old throttle cable to blame (i think) but now thats not an issue.

right where the rod on the side of the plate goes down the side of the carb i can feel a binding with my hand. when it sticks you cant easily push it with your fingers into a closed position… you have to rap it with something.

im pretty pissed off that i spent money on a brand new carb and im more than likely going to have to open it up and start screwing around with it.

Offline txchainsawgogi

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Re: throttle plate sticking open when slightly revved
« Reply #1 on: February 05, 2012, 03:24:43 pm »
is there anything i should know about autoline carbs, as in… anything internally that is poorly built and would cause my super high idle and my plate to stick open?

Offline Donut

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Re: throttle plate sticking open when slightly revved
« Reply #2 on: February 05, 2012, 05:24:05 pm »
If the throttle shaft is binding, take it back.  Either it was bushed without a cleanup, or it was never bushed and needs to be.
Did you also change the return spring?  I was surprised how weak my old one was.
'73 Chevy K-20 ***SOLD***
350/tbh350/np205
My plow was half price if i took the truck with it.

'86 C-30 dually, 454/tbh400

Offline Jason S

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Re: throttle plate sticking open when slightly revved
« Reply #3 on: February 05, 2012, 05:35:17 pm »
Throttle plate or Choke plate? 

The photo shows the choke plate. You may have to do some slight adjustments to the choke mechanism to get it properly setup; as well as a bit of fine tuning for the idle speed and idle air mixture. 
« Last Edit: February 05, 2012, 05:38:47 pm by Jason S »
1973 GMC K2500, Super Custom, Camper Special, 350, TH350, NP203, 4.10's
1974 Chevrolet K10, Custom Deluxe, 350, SM465, NP203, 3.73's

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Offline txchainsawgogi

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Re: throttle plate sticking open when slightly revved
« Reply #4 on: February 05, 2012, 06:37:50 pm »
it actually just fixed itself… im thinking the bushing isnt in there right… or has some metal burrs on it affecting things.

and yes, i meant choke plate. im going to have to do something about it BUT its my daily driver, and i just gave them my old running carb for the core charge.

Offline rustyMUD

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Re: throttle plate sticking open when slightly revved
« Reply #5 on: February 05, 2012, 11:23:17 pm »
is there anything i should know about autoline carbs, as in… anything internally that is poorly built and would cause my super high idle and my plate to stick open?

I purchased an Autoline carb from Rock Auto a year ago.  Its a Rochester Monojet for my 292.  The base of the carb was cracked and held together with what looked like JB Weld.  The throttle shaft bushings were worn out and there was noticeable slop in the throttle shaft.  This made me wonder about the internal components.  I tore into it and found dirt...yes DIRT in the float bowl.  Also, the float was off by 5/32.  I cleaned out the float bowl, reset the float and sealed the throttle shaft bushings with teflon tape.  I had considered sending it back, but I needed the truck on the road immediately. 
    The carb has been on the truck for a year now.  The auto choke never worked properly, even after constant adjustments, so I put on a manual choke setup and called it good.  In summary, yes I've had bad experiences with Autoline carbs. 
    Another thing, these are not "Brand New" carbs.  They are re-manufactured carbs, and it appears that they are rather poorly re-manufactured.

Offline txchainsawgogi

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Re: throttle plate sticking open when slightly revved
« Reply #6 on: February 07, 2012, 09:01:27 pm »
well i knew they were remans… so i guess i meant "new to me". i didnt realize it could be so bad. i gave the carb an intense looking over before installing it and it looked really really clean, and everything worked smoothly. but after the choke plate getting stuck and then fixing itself im not so sure.

are there many horror stories about these carbs? i couldnt really find product reviews online.

Offline Dr_Snooz

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Re: throttle plate sticking open when slightly revved
« Reply #7 on: February 08, 2012, 12:41:19 am »
If your throttle cable is kinked, it will cause all kinds of binding at the throttle. If it doesn't have a straight shot at the throttle linkage (like if the cable ferrule breaks or is missing), it will bind.
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60