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i'm sorry to write a book about this, but i feel this is the only way we'll solve it.

Background:
quadrajet
HEI ignition
Stock-ish cam---like 184/195 @ .50"---- so decent vacuum etc.

1) Prior to the no start/difficult to start problem, the engine would start cold within 1 crankshaft revolution if not less. Hot start was a little cranking and possible some pedal intervention---maybe 1/2 down. Still acceptable.

2) The ONLY thing i did IMMEDIATELY prior to the problem was to adjust the secondary throttle plates to open more. NOT the secondary air flaps, but the actual throttle plates. The secondaries really weren't opening at all when the primaries were at WOT. IMMEDIATELY after i did this did all the problems start.

So, in order to adjust the secondary opening, you have to adjust tab "A" towards the direction of tab "B." (i think?) More opening = more towards "B". Less opening, less towards "B." (This isn't the actual carb, but the linkages are all the same)


i don't remember exactly, but this is very likely how i did it:



So, what i THINK happened was i got "too enthusiastic" and pressed down counterclockwise on the wrench holding the throttle arm---in order to counter-act the f forces of moving tab "A" clockwise towards tab "B."

But, in doing this what MAY have happened was that now tab "C" became bent----the throttle stop for the primaries----which means that the primaries are now closed more
than they usually are.



i then experienced stalling and the only way i could keep the engine running above 1000 rpm was to keep my foot on the pedal---because of course the engine will stall when you take away either air, spark or fuel. i have since, probably, solved THAT problem by turning up the idle screw. But that's not important now because what good is that if i can't get it started?

So, where we stand now is the engine may not start cold---50/50 chance. And even if it does start, it doesn't start normally----more of a putter to start with lots of cranking. The engine WILL NOT start hot unless you wait at least an hour.

Here is a video to better illustrate: We see here at about 9 seconds we hear the electric fuel pump come on. Then at about 15 seconds, i give it a shot of gas. Then about 7 seconds of cranking and only when i press the pedal down---(look closely at the top left corner to see the accelerator pump pushrod move) does it start.


What would this tend to indicate? Also, i know the choke flap probably shouldn't be flopping around during cranking. i have since fixed that, but it didn't make a difference.
 

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You really need the ID number off the carb. There are very specific setup instructions for the QJet that vary by model number.

In general the choke is not super tightly closed when cold but this has two versions for those with a divorced choke meaning the thermal coil is in the intake manifold boss heated bu th exhaust cross over the cold adjustment is lightly closed such that cranking air flow can push it open about 1/4 to 5/16ths inch. When the choke thermal spring is integral with the carburetor whether using exhaust heated air or electrically heated the cold choke plate has about 1/8th to 1/4 inch edge opening set statically.

The secondary throttles should be tight closed until the primary throttles are 3/4qtrs open.

You should buy the Doug Rod, Bill Fisher book Rochester Carburetors from H.P. Books, ISBN 0-912656-10-6 it is about the most comprehensive write up on this carb. The Cliff Ruggles book, Rochester Quadrajet Carburetors is a good addendum for hot rodding the carb.

Bogie
 
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