Just can't get rid of them hesitation blues!

[flipper]

Step hard on the gas just a little and she hesitates, bucks, stutters, whatever you want to call it, and then smooths out. Started doing this when some bozo (not me for a change!) installed new intake manifold to get rid of vacuum leaks from the old. car is 76 w/ weber 32 36 and crane xr700

So far I have: changed plugs and wires; set and reset the timing; sucked on the dizzy vacuum tube and gotten vacuum, as well as movement from the doohicky inside the dizzy if i sucked REAL hard; reset the weber float level; messed constantly with all the Weber screw settings as per redline's instructions; cleaned the primary jet; checked for vacuum leaks (none); etc etc ad nauseam ad infinitum.

what should i try as a next?

one thing i noticed yesterday is, starting w/ a cold motor, when i worked the throttle all the way, the *lower* butterfly on the primary barrel of the Weber opened all the way, but the other butterfly, on the second barrel, opened only 1/4 to 1/3 of the way. if it's supposed to open to vertical just like the primary one, how can i adjust it?

any other thoughts and/or suggestions? it seems to me it should be something that the manifold-replacing mechanic dude could have messed up while doing the replacement. i stood over him and watched while he did the replacement and saw nothing obvious happen. but on my test drive right after the new manifold was installed, thar she bucked. so, whatever happened had to have happened during those two hours.

(btw/ when i turned around and brought the car back to the shop, the boss man took a drive, got a good feel for the bucking, and said .... "How do I know it wasn't doing that before?" as it happens, my town is filled w/ turds like that!)

[Mike Self]

All the stuff below presumes the ignition is up to snuff (points, plugs, timing etc) and there are no vacuum leaks.

The hesitation you describe could be too much air (lean situation) or too much gas (rich mixture). It'll be a lot easier to diagnose once you determine that. If your plugs come out black after a few miles, it's too rich. Also, if you're running plugs that are too cold, they can load up while idling--esp with a rich mixture. Now for the carburetor diagnosis:

1. Accelerator pump output. With the engine off, work the linkage while peering down the primary barrel throat. You should see a healthy squirt of gas coming from the little nozzle poking out into the airstream from the float chamber side of the primary barrel. No dribbles, but a squirt. No squirt or dribble means either a bad accelerator pump diaphragm (most likely) or a worn linkage to the pump.

2. I presume you've cleaned out all the jets and they are the proper size.

3. On a 32/36, the primary throttle plate (down at the bottom of the carb body--the upper plate is the choke, which should be vertical--and stay vertical under acceleration--with the engine warmed up) should be about 3/4 fully open before the second barrel begins to open--that's why it's a progressive carburetor vs the 38/38, which is a synchronous one--both barrels open together simultaneously. If the second barrel is opening too soon, it can cause a hesitation.

Check these and report back.

cheers

mike

[flipper]

1/ lean or rich: have not tried the plug diagnosis but i have used the idle mixture screw to run it both leaner and richer and the bucking occurs either way.

2/ i am presuming that the primary side is the side that opens all the way. in the pix below, that'd be the barrel on the *left* side. well, when i work the linkage, i get *no* squirt on that side. it's all in the other barrel, the one on the right in the pic, which i'm assuming is the second barrel.

3/ Under acceleration, the left throttle plate opens up to a vertical position, while the right throttle plate, when floored, opens up only about a third of the way, as kind of seen in the picture if you click on it to make it larger. I think it's opening progressively but it's sort of hard to tell; at the very least I can tell it's not opening simultaneously with the left plate.

so, okay, unless i've lost my marbles, the squirt is going into the wrong chamber. could that be possible? if so, how do i fix that?

sheesh!

[Baikal.2002]

I'm no expert but my 32/36 has the primary on the inside, closest to the engine, and secondary on the outside. The attached image shows my linkage, a little fuzzy, but should give you an idea how yours should look. Take a look at the schematics for details on how it goes together.

HTH

[KFunk]

It's probably not related to your hesitation, but I'd adjust that throttle linkage to make it so the secondary barrel opens all the way when you push your foot to the floor. It'll make the car a whole lot more fun.....

[flipper]

my carb is the DGEV and, according to its schematic, the primary plate *should* be closest to the engine and choke and *should* be the plate that is opening 100% from the start.

on my car, however, it's the other plate that is opening 100% from the start.

in other words, things are ass backwards. the gas is shooting into the correct barrel but the wrong barrel is opening first.

if i'm right in this assessment, please don't tell me to fix it. instead, please tell me *how to* fix it. what do i need to change to reverse the firing order of the two plates?

thanks!

[eurotrash]

my carb is the DGEV and, according to its schematic, the primary plate *should* be closest to the engine and choke and *should* be the plate that is opening 100% from the start.

on my car, however, it's the other plate that is opening 100% from the start.

in other words, things are ass backwards. the gas is shooting into the correct barrel but the wrong barrel is opening first.

if i'm right in this assessment, please don't tell me to fix it. instead, please tell me *how to* fix it. what do i need to change to reverse the firing order of the two plates?

thanks!

I believe what you are describing is physically impossible with properly functioning stock linkage. The throttle shaft is directly connected to the end of the primary shaft. As you push the pedal, and the linkage rotates toward WOT, the secondary doesn't even come into play until about 1/3 of the way through the primary shaft rotation when the tabs connect and the secondary is actuated..

The only way the secondary butterfly could open first ... No..Seriously, I'm not even sure you could make it happen if you wanted to... The primary MUST rotate to affect the secondary. Period.

You need to find someone who can stand over the car and assess the problem. If it worked fine before, It probably was reinstalled incorrectly and/or was damaged and you have something binding.

[flipper]

i have no such person to help me but i do have a long-distance pal with a weber in his 02 and we're going to do a phone consult this evening, both of us standing over our weber carbs as we do it. hopefully, that'll tell me something.

meanwhile, here is the schematic of my carb:

http://www.webercarbsdirect.com/v/vspfiles/weber_carburetor_schematics/3236DGAVEV.pdf

if i'm reading that right, then the primary flap is indeed on the side toward the choke. but as you can kind of plainly see in the last three pictures in my 2nd post, the flap on the left barrel is wide open (this one is farthest from the choke) while the flap on the right barrel (closest to the choke) is only partially open. (The individual close ups are cropped from the both-barrel picture directly above them.)

of course, i could be in the middle of a great big brain fart and this is all a dream. then again ...

thanks for your help!

[Baikal.2002]

Can you post a pic of the back/firewall side of the carb?

EDIT: Attached a pic showing the linkage opened to the point where the secondary is going to start opening. Does yours look different?

[flipper]

here are some pix of the linkage, both toward the firefall and toward the carb itself. hope it shows something revealing!

will study your picture and get back on it ...

[Baikal.2002]

Something looks off with the lever that opens your secondary. It shouldn't have that gap. I'd disconnect the rod from the firewall to the carb and actuate it by hand. If your primary isn't opening before the secondary there has to be something wrong with the primary shaft, bent or broken.

[KFunk]

OK, So where the horizontal throttle rod goes in, is the primary shaft. So when that whole thing spins, it'll open the primary barrel. Note that the arm that reaches over to activate the secondary barrel, is also on this shaft. However, it should just be free-wheeling and staying in place until that little bent over tab on the top of the shaft contacts it, and pushes it around. It should have some washers and grease and such that the primary shaft doesn't automatically rotate that arm, until the tab hits it. I'm wondering if its too tight together and instantly spinning it. As for why the primary (on the right) isn't opening, that's really weird.... it should just go with the shaft as well....

[Baikal.2002]

Kfunk has a good point. The secondary lever might have popped off the bushing and be binding, opening the secondary before the primary opens fully. You might be able to tap the lever back down onto the bushing if it hasn't galled it badly. Also with as many threads as you have showing on the rod that runs down the firewall to the pedal box your linkage isn't adjusted correctly to open the primary fully.

[flipper]

Kfunk has a good point. The secondary lever might have popped off the bushing and be binding, opening the secondary before the primary opens fully. You might be able to tap the lever back down onto the bushing if it hasn't galled it badly. Also with as many threads as you have showing on the rod that runs down the firewall to the pedal box your linkage isn't adjusted correctly to open the primary fully.

I think we've got a winner!

I went over everything with my buddy and confirmed that things are ass backwards.

One thing I noticed is that when I press the throttle all the way down, it hits a dead end before it can open the primary fully. do you have a guess as to how much higher it should be on the vertical rod?

as to the bushing on the secondary lever, is there any way you could post a picture of that area and point to the bushing with an arrow or some such? hopefully that'll indicate to knuckledragger me what area of the level i should tap, as well.

thanks once more ...

edit: disconnected the vertical rod and plunged the throttle without it, and still it stops before the primary flap can open completely. i tried to see what the blockage is but i can't puzzle it out. any thoughts?

[Baikal.2002]

EDIT: Looking at the schematic it looks like the bushing is actually behind the lever not in front as in the attached picture.

Assuming that the secondary lever has jumped off the bushing, causing the binding and that the bushing isn't worn out,galled or otherwise fubar'd....I'd try and wiggle the lever onto the bushing before tapping or prying on it with anything as you don't want to damage the shaft or any of the other bits.

Binding gone? Now, unclip and pull the threaded rod from the lever arm, inside the car put a brick on the pedal to keep it floored, back outside actuate the carb linkage to wide open throttle and adjust the nut/thingamabob on the threaded rod until it will slip into the hole in the arm you pulled it out of. If you don't have enough threads to leave three or four at the end you'll need to crawl under the car to make an adjustment on the lever at the pedal box.