Carb

[fiat218]

sorry ,let me explain
when i put the accelerator down by hand and look down inside the carburetor, only one side opens up,i have to really push hard for the other side to open,and that is just by hand standing on the outside of the engine.

SO IF I WAS TO GRAB the rod on the carb, depress it all the way .or half way, should the butterflys open? both

[bradartigue]

sorry ,let me explain
when i put the accelerator down by hand and look down inside the carburetor, only one side opens up,i have to really push hard for the other side to open,and that is just by hand standing on the outside of the engine.

SO IF I WAS TO GRAB the rod on the carb, depress it all the way .or half way, should the butterflys open? both

It should open fairly easily. Disconnect the accelerator rod and rotate the throttle by hand. If it is difficult then remove the carburetor and try it again. You may need a larger spacer between carb and manifold.

[fiat218]

sorry ,let me explain
when i put the accelerator down by hand and look down inside the carburetor, only one side opens up,i have to really push hard for the other side to open,and that is just by hand standing on the outside of the engine.

SO IF I WAS TO GRAB the rod on the carb, depress it all the way .or half way, should the butterflys open? both

It should open fairly easily. Disconnect the accelerator rod and rotate the throttle by hand. If it is difficult then remove the carburetor and try it again. You may need a larger spacer between carb and manifold.

ok thanks, that was my next question, if i need to do a bigger spacing?

as i took the linkage off the accelerator, and open it by hand,the secondary will open when it is depressed wide open,there no way they open half ways or in any manner as i drive,so ? is that how it works? i thought they both open when u give it gas to get quicker acceleration, not when u have to floor the car and passing gear kicks in. this is a automatic. i have to say something is not right in my mind? or is is

[bradartigue]

The secondary should begin to open when the primary is about 1/2 - 3/4 open. When the primary is fully open and the throttle fully engaged both barrels should be full open.

The carburetor does not know what gear you are in, so automatic or manual does not matter.

[fiat218]

The secondary should begin to open when the primary is about 1/2 - 3/4 open. When the primary is fully open and the throttle fully engaged both barrels should be full open.

The carburetor does not know what gear you are in, so automatic or manual does not matter.

ok thanks, well it don't work that way u said, so now i will remove it and see what makes this thing tick

[Weelan]

It doesn't function that way even when you just twist the throttle linkage on the carb itself? My guess would have been that your linkage was too short and not opening them all the way. or something along those lines.

[fiat218]

It doesn't function that way even when you just twist the throttle linkage on the carb itself? My guess would have been that your linkage was too short and not opening them all the way. or something along those lines.

i have not removed the carb yet to check

OK HOPE I CAN EXPLAIN WHAT I SEE
\ i took the carb off, made sure that it works off the car,put it back on, works installed, no problems
NOW
i hook up the linkage just to the carb, and hook it to the other end for the throttle cable/ as i watch and depress the linkage down motion , i see that the secondary opens BUT snaps shut again. now let me remind u i am holding the linkage down .just enough where the secondary is open,then in a second it goes back to closing, i can move it farther down (the linkage ) and hold it there and watch it close again/ WHY

does some one have a answer as to why the secondary would close by it self when it is open?

[fiat218]

can any one tell me why i am having this problem with the carb,
thanks

[Weelan]

Hm, when it was off the engine it wasn't doing that though? can you get some pictures? I think that would be helpful. especially if you can get someone else to push the gas pedal down. take a picture down the barrels, but also take a picture of the linkage on the side of the carb. one right when the throttle is fully opened and one after the secondary closes by itself with the throttle still open. I say get a helper because it might be hard to take these pics while holding the throttle linkage open.

The secondary will only begin to open at 75-80% throttle, but it should stay open once you've passed that threshold and open further as you press more. May be worth noting that it's significantly harder, by hand, to press the linkage further beyond the 75%ish point.

[fiat218]

Hm, when it was off the engine it wasn't doing that though? can you get some pictures? I think that would be helpful. especially if you can get someone else to push the gas pedal down. take a picture down the barrels, but also take a picture of the linkage on the side of the carb. one right when the throttle is fully opened and one after the secondary closes by itself with the throttle still open. I say get a helper because it might be hard to take these pics while holding the throttle linkage open.

The secondary will only begin to open at 75-80% throttle, but it should stay open once you've passed that threshold and open further as you press more. May be worth noting that it's significantly harder, by hand, to press the linkage further beyond the 75%ish point.

When it off, it works ok, when it on, it like it open but then close,s on it own

[bradartigue]

can any one tell me why i am having this problem with the carb,
thanks

I'm not trying to be cruel here, but your explanations don't give a lot to go on. Have you read any documentation on your carburetor and tried to understand how it is supposed to work?

If the secondary snaps back shut when you have the primary fully open and are holding the primary open then your linkages are messed up. But I can't figure out if you are saying this is what is going on or not.

Study a diagram on ANY Weber downdraft carburetor (the 34DMS and 34DMSA are almost identical in operation to your carburetor), then give us some ideas of what you are seeing, and pictures would definitely help out.

[fiat218]

can any one tell me why i am having this problem with the carb,
thanks

I'm not trying to be cruel here, but your explanations don't give a lot to go on. Have you read any documentation on your carburetor and tried to understand how it is supposed to work?

If the secondary snaps back shut when you have the primary fully open and are holding the primary open then your linkages are messed up. But I can't figure out if you are saying this is what is going on or not.

Study a diagram on ANY Weber downdraft carburetor (the 34DMS and 34DMSA are almost identical in operation to your carburetor), then give us some ideas of what you are seeing, and pictures would definitely help out.

Picture won't do justist, I will put it this way, when I put the throttle down, as I put it down by hand and watch the primary open,then farther down the secondary open a tad,which is great,now it working good, but now as I hold that steady the secondary will go shut,now I have not moved anything, now I push open the throttle more down and secondary open farther, as I hold that postion ,the secondary will snap closed again, no matter where I open it to it closes, why

[bradartigue]

Sounds like your linkage is out of adjustment or broken. I have no idea how the secondary could be flapping shut and then opening again and flapping shut again. That linkage isn't very complex, the opening of the secondary governed by the movement of the primary arm.

You are talking about throttles and not cold start (chokes), correct?

[fiat218]

Sounds like your linkage is out of adjustment or broken. I have no idea how the secondary could be flapping shut and then opening again and flapping shut again. That linkage isn't very complex, the opening of the secondary governed by the movement of the primary arm.

You are talking about throttles and not cold start (chokes), correct?

Yes throttles, let's just say u push your throttle down half way, secondary opens up, u hold that steady, now your car is not running,,so u hold your throttle to one point and your secondary opens,as it should, now at that point the secondary just closes, and u have not moved nothing, now why would it just close on u.! It like it slips back to the closing position

[Weelan]

I'll go out and look at mine in the morning.

I'm thinking the linkage on the side might possibly be slipping or something or at least not holding firm enough to keep it open.