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85 Chevy w/ 305 having some Issues!!! & I'm Stumped

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85 Chevy w/ 305 having some Issues!!! & I'm Stumped

Old October 8th, 2012, 5:04 PM
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Exclamation 85 Chevy w/ 305 having some Issues!!! & I'm Stumped

Ok.. I recently bought a 1985 Chevy K10 4x4 and new some major help. It ran out fine when I bought it though would not idle. Top end ran good!

EGR was bad so I blocked it off. Helped but still not right so I replaced the carb with a REMAN Rochester Quadrajet identical to what was on it. Adjusted it to best I could and as it warms up it seems to idle fine BUT...

It started running better though when cold will not want to start and when it does it runs real rough until it warms up. Further more, when running okay on bottom end it now cuts out on the top end when I really get into the throttle. Almost complete opposite when I frist brought her home.

At first we thought it was getting too much fuel but we have turned the mixture screws down and played with those back and forth. No change.

It has new plugs and wires. Choke light comes on when starting as it should but am told that is due to how it is wired. Choke should be fine as it came with the new carb. Right?

I have adjusted the timing by moving the distributor back and forth and seems to help but goes right back to same symptoms. So I am not sure it is timed 100% correct.

Please help a new member... Thanks in advance.
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Old October 8th, 2012, 5:24 PM
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Electric choke, thats where I'd start.
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Old October 8th, 2012, 6:22 PM
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vacume leak ? screw the idle adj. screws in to stop. back them out 1 1/2 turns. plug all vac. hoses, start it and see if it changes when you choke it with your hand across front of carb. vac hose to body is suspect if hvac is weird
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Old October 10th, 2012, 9:19 AM
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well i have done a compression check and all cylinders are between 115-125 so all is good there. someone told me could be weak lifters or even flat spot on cam.

myself and another guy did a little inspection and found the choke pull-off is not working correctly. it will not open the primary upon start up and floods the engine like no other...

the choke pull is vaccum controlled and all lines have been inspected but probably need to do a vaccum test to verify choke pull issue. suggestions?

i put a call into the carburetor supplied and have not heard anything.
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Old October 10th, 2012, 2:45 PM
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First the idle air screws are to set the vacuum. You should be close with them at 1/2, best to use a vacuum gauge adjust both together till you get to max vac at idle, idle around 700-750 with a/c. Your dealing with primative ccc stuff. First the choke plate should be full closed at cold, you state it is going open on start? This sounds strongley to me like a float level too high. Have you seen fuel spill over into the venturis at any time? Black smoke at anytime out of the tailpipe?
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Old October 10th, 2012, 2:47 PM
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I should have added, you say vacuum, do you mean hot air? Is there a small tube into the intake that goes to the side of the carb?
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