No start/hard start cold or hot:

[Stewart G Griffin]

i'm sorry to write a book about this, but i feel this is the only way we'll solve it.   (Also, you can probably guess how i roasted my starter in the other thread.....)

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.

https://www.youtube.com/watch?v=QCqjXfUrdco

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.

[VileZambonie]

Undo

IMMEDIATELY after i did this did all the problems start.

[Stewart G Griffin]

Can't really undo because the secondary plates do close completely----nothing really to undo.   And primary throttle idle speed has been brought back up.



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?

[VileZambonie]

How is the vacuum advance hooked up? Ported or full vac? What is your ignition timing set at?

[Stewart G Griffin]

It's ported---so i'm thinking  i'm getting advance when on high and mid idle, but losing it during curb idle?

i haven't checked timing yet.

Despite the fact that i agree with checking ignition first and  that most carb problems are actually ignition problems, i don't think ignition is the problem here as i basically got it to start "normally" again-----starts within 1-2 crankshaft revolutions.

All i did was to take the idle tubes out, blow compressed air thru them and run a wire thru them.   Also, blew out the area underneath the idle tubes---the idle wells?

i'm not 100% convinced that this solved the problem as i did not see any dirt or  debis come out.   Nevertheless, the no start/hard start problem is basically "solved."

Next problems:
1)Still dies once you put it in gear
2) can't restart hot (although it seems improving----it sounds like it almost wants to start)

[blazer74]

What do mean by took the idle tubes out, you mean the mix screws or did you take the top of the carb off?
By the way the unloader comes into play only at Wide open throttle.

[Stewart G Griffin]

What do mean by took the idle tubes out, you mean the mix screws or did you take the top of the carb off?
By the way the unloader comes into play only at Wide open throttle.

No, the actual idle tubes---had to take the top of the carb off to do this.

Now, i also did take the idle mix screws out and shot compressed air thru those passages as well.

[blazer74]

Stalling when put in gear cold can be a misadjusted choke, bad or misadjusted pull-off.
Basically it wants more fuel to keep running.
You didn’t touch any of  that initially to cause this problem.
Does it stall in gear  fully warmed up also?
The accelerator pump is giving good streams of fuel?
A cold engine with a Quadrajet will be hard pressed to start without a pump shot.
When you put a wrench on the throttle did you apply enough pressure to twist the primary  throttle shaft or crack the throttle plate casting?
If the primary throttle blades are misaligned this will cause issues. I’m curios on that due to you had to adjust the idle speed after bending things.
By all means make sure the ignition system is ok.
If it’s on ported vac and was before the problem that shouldn’t effect anything, you could try manifold vac and adjust idle speed to see if it helps your in gear problem.

[Stewart G Griffin]

Stalling when put in gear cold can be a misadjusted choke, bad or misadjusted pull-off.
Basically it wants more fuel to keep running.
You didn’t touch any of  that initially to cause this problem.
Does it stall in gear  fully warmed up also?
The accelerator pump is giving good streams of fuel?
A cold engine with a Quadrajet will be hard pressed to start without a pump shot.
When you put a wrench on the throttle did you apply enough pressure to twist the primary  throttle shaft or crack the throttle plate casting?
If the primary throttle blades are misaligned this will cause issues. I’m curios on that due to you had to adjust the idle speed after bending things.
By all means make sure the ignition system is ok.
If it’s on ported vac and was before the problem that shouldn’t effect anything, you could try manifold vac and adjust idle speed to see if it helps your in gear problem.

Yeah, the problem now is that it will stall in gear warm.

i may have had the throttle plates opened previously to where it was maybe on the main circuit when idling?

[blazer74]

Ported vac can cause nozzle drip, would idle rich.
Manifold vac will allow you to lower the throttle angle.
Did you mess with the distributor weights and springs at any time.?

[Stewart G Griffin]

Did not mess with anything in the distributor or timing.   i also checked vacuum advance can to see if it was working properly and checked the springs and weights and they seem to be normal.

[Stewart G Griffin]

Timing is at approx 8-10 deg btdc  (couldn't see exactly because the tab is not easy to see at the angle my head had to be at, but it's definitely between 8-10)


i specifically set the throttle plates so that they're just below the ported vacuum "slot" in the venturies and the transition slot is just a little exposed.