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 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.
Is there spark at the plug while cranking? If not, I'd change the ignition module. I'm leaning on the old adage that most carb problems are really electrical.
First step to me would be go back to original settings, Beside that the carb probably rebelled against being screwed with with a freaking crescent wrench and vise grips. Crescent wrenches are for farm equipment with square bolt heads but not for carbs.
Every Quadrajet I've owned, that actually worked good, were good carburetors, but once they had problems, they went in the scrap.
If the choke isn't working correctly it can prevent the secondary throttle plates from opening. The choke has to be fully open for the lever on the passenger side to move allowing that to happen. And yes, your timing is advanced too far.
You also have a rather weird sounding "crank"..as in perhaps a valve problem, cam problem, starter binding on the flex plate...it just doesn't sound right when cranking but that's just me...
i don't necessarily disagree with the timing too advanced, but what do you base this on? i'm running ported vacuum, so i think i'm getting vacuum advance at hi-step, mid-step and even some at curb idle? This starter toasted shortly after i made this video last week (gee, wonder why......). i got a new starter put on (see my other thread entitled "starter talk")
They are basing it off the “hard to turn over” at first start, then a few revs more it does the same thing. Now could have been your weak starter that went out, fuel puddling up on the piston, etc. Did you mention the base timing?
If the motor started before when cold without stepping on the gas pedal, why are you pushing down on the gas pedal before you crank the motor now? You are likely flooding the motor with too much gas by stepping on the pedal before cranking it now. With a crescent wrench and a pair of vice grips working over the carb linkage, do you have any idea what all has been bent? Especially if your twisting one tool one direction and the the other tool the opposite direction. your "enthusiastic" bending may have even bent the primary throttle shaft or messed up all sorts of linkage that needs to be correct for things to function. You have a carb to look at, maybe you can put everything back close to where it was to start with by copying the other carb's linkage. You may want to try to start the motor with the top choke plat held open and see if the motor will start. If the motor was flooded with gas too much, you may need to put a new set of spark plugs in it before it will start. Gene
To be honest, i don't know what base timing is because i never took base timing because there was too much crap in the way of the timing tab. i'm not proud of it, just being honest here. The timing could very well be too advanced as before all of this i turned the distributor all the way clockwise until the vacuum advance can hit the vacuum modulator tree (for transmission) on the intake. BUT, the engine started easy back then (although didn't crank easy) and the engine ran just fine with no pinging. Again, not bragging, just being totally honest. Now, i did back it off a little after this starting problem happened, thinking this would maybe make it easier to start. i'm not against doing things the right way; i'm just telling exactly how i did what i did.....
i should have mentioned that the way i always started a cold engine was to press completely down on the pedal, release, then crank. Easy starting within 1 crank revolution if not less.
I think that was the way to set the choke on a carb,,,,,press the pedal down,,,,that would release the choke and let it close . Then start the engine. Plus that extra shot of fuel was good for a cold engine . I’m sorry I can’t help you with your carb problem,,,,,I’m just so so at it,,,,,but there are some carb experts here,,,just keep trying. From what has already been said,,,,Rochester quads are good carbs ,,,until they go bad . Or worse yet,,,,we make them bad by bending things and causing more issues . I didn’t understand at all why you were concerned about the secondary not opening,,,,and wanted to bend a bracket . Usually,,,if the secondary is not opening correctly,,,it means there isn’t enough vacuum to draw it open . Unless there is something binding,,,,,and even then,,,,,the side you were bending things on should not affect that . Looked like you were bending the primary shaft lever,,,,,I was lost after that . Please forgive me if I am misunderstanding what you were doing . It was running and starting good until you bent some parts,,,,put it back like it was . I know there have been several others that have been online since this thread posted,,,,but have chosen not to get involved,,,,,,I’m not sure why ? Although,,,,,I usually don’t either,,,,,,when I see the user profile and there is basically no information what so ever . Sorry,,,,,I hope you can get it fixed . Tommy
How about starting from scratch. Get the base timing to 8-10 BTDC. Now you mention too much stuff in the way, could it be you maybe don’t have a timing tab on it? It’s all good. Ways around that.
Hey guys, it started before he bent stuff, doesn't start after he bent stuff. Bending the stuff has caused the starting problem, most likely. The 1st rule of troubleshooting is determine what as changed, and undo the change. Then work from there.
I agree to a point Gene, but ( hate to talk about him in the 3rd person ) did he compensate for an original issue, maybe he didn’t notice the “womp womp” when starting it, and then wanted more out of the engine and went to the carb and that compounded the issue? I still stand by start at the beginning of what’s needed for the engine to start up then fix any carnage that may have ensued
i am leaning towards this, but what went out of whack? i took the carb in question off the engine (several times already actually) and compared it to my extra carb---the one in the pics. Everything seems to match. Granted my knowledge of q-jets is pretty novice. i even set the primaries to be just below the horizontal "slot" in the bores for vacuum advance.
Just my suggestion, but start from timing. If you’re sure base timing is correct or pretty close, then move on to the fuel delivery issues you may have. Keep in mind fuel delivery could be too much, or not enough.
As others have said, it started and ran before you tweaked the linkage and now it doesn't. My guess is that the secondary throttle plates no longer close properly and you now have a massive vacuum leak. At any rate, I think it's time to get a new carburetor that's been professionally built, or take yours to someone who knows how to build a Quadrajet.
Battery sitting = 12.56 Battery while cranking = 11.50 ish Voltage at red/ ignition wire with key "on" = 12.56 Voltage at red/ ignition wire while cranking = 10.8 ish. Is this good enough for HEI to start engine?
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