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Rochester Quadrajet Manuals

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How to unblock idle jet on Rochester Quadrajet

I also battled with the carb in the beginning with exactly the same symptoms.

Quadrajet Manuals 1 and 2 on this page was very helpful, Read the Diagnostics Dilemma article first.

In the end I think my main problem was with the fast idle feature on the right of the carb (vehicle's right).
Also the choke wasn't set properly
And Also the air correction screws were screwed in too much.

You will probably find that once the engine is hotter it will idle and start easily.
The fast idle is not set fast enough, so idle speed when choke is closed is to slow and that is why it dies.

If you put little fuel in and it start, keep the throttle open a very tiny little bit and it might run, mine did. Keep it like that until it is hot. Thumbsuck I would say 1800 rpm.

In one of the performance article I read on the quadrojet the guy said GM made the air correction port so small that if a stupid mechanic turn out the screws way too much the engine will still run. So in the end I decided it cant do damage. When the engine idled I turned the screws in until the first sign of uneven idling, then I screwed it out 450 degrees ie. One and a quarter turns. I also made sure from the uneven idle point I unscrewed both screws exactly the same amount.

Then the ignition timing. Mine did not have TDC marks on the pulley or balancer. I made marks and I've read articles and tried various settings. In the end a friend who are racing a 350 Chev on Killarney told me to stop wasting my time and set the timing like so:
Let the car idle. Turn the distributor one way until the engine start to run unevenly and mark the position, then turn the distributor the other way until the engine starts to run unevenly and mark the point. Now turn it back halfway between the two points and keep your timing there.

Incorrect ignition timing will also cause hard starting.