Chinese 34 ADF Swap Help Needed

[btoran]

So I received a brand new Chinese 34 ADF (the previous one was damaged in shipping), and am getting ready to install it in the car. it will be replacing the stock weber 32 adf that is already already there. I thought this was a plug and play unit (and maybe it is), but there are some things on the 32 adf that aren;t on the 34 adf and i'm not sure if i need them or not, so please help.

in this picture of the old carb taken from the right fender looking across the engine bay, i put green tape around a hose.


in this picture of the new carb, i can't seem to find the same spot for the hose. i added green tape approx where i would expect to find it.


so, what is this hose for and do i need it?
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next question....

in this picture of the old carb taken from the front of the car, i put blue tape around a hose.


in this picture of the new carb, i can't seem to find the same spot for the hose. i added blue tape where i would expect to find it.


so, what is this hose for and do i need it?
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next question....

in this picture of the old carb taken from the front of the car, i put white tape around a hose.


in this picture of the new carb, i can't seem to find the same spot for the hose. i added white tape where i would expect to find it.


it looks like the small bowl on the old carb could be fitted to the new one (there are 3 holes for it), but i'm not sure if it's needed. so, what is this hose for and do i need it?

[btoran]

well, i did a little more digging and found the hose with the blue tape and the hose with the green tape go to bottom and top (respectively) of this canister tucked into the front of the engine bay near the driver side headlight.


so, what is the canister and do i need it connected?

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also, the hose with the white tape goes to the round silver canister with the screw in the top toward the bottom right of this picture.


it then exists the other side, crosses below the hose with the green tape and is connected below and slightly to the right of the hose with the green tape in this picture.


so, what is it for and do i need it?

inquiring minds want to know (and get on with the carb swap). thanks.

[carl]

The large black cylinder is your charcoal canister for dealing with gas vapors from the gas tank. To answer your basic question, you don't really need either of those hoses hooked to the carb for it to function properly.

carl

[btoran]

so all of the hoses (those i labeled with green, blue, and white tape) are not needed?

so what happens to the gas vapors from the tank if i disconnect the charcoal canister ans it's components?

[bradartigue]

A bit of history - the ADF series has connections for things that didn't exist in 1974/75. So yes, some things aren't going to connect.

The small port on the base, you have a yellow cap, it is for the advance vacuum on an electronic distributor. If you have a Marelli electronic distributor from a stock 1979-1985 Spider then you need that hose to pull the diaphragm. The blue one is a vent line, and the Chinese 34 (and really the real Weber 34 I'm looking at now) don't have it. So no vent. Since you have no vent line you have no need for the charcoal canister. The white line is for the high idle thing. You don't have it on the carb, you can't connect it to your car. The green one is also part of vapor recovery; you don't have the connection so block it off.

Look at it another way: The only connection you need to run the car is the fuel inlet line. Everything else can be blocked off and the thing will run. I like to have a fuel return line so I always connect it or make one with a bypass filter (you have the connection so use it). The last necessary connection is to the electronic distributor, if you have one.

[So Cal Mark]

capping the fuel evap canister may result in excess pressure in the tank. You can leave the canister connected to the tank, connect the vacuum hose to the carb and merely cap the port that led to the float bowl. At least that way you're not spewing vapor from the tank into the atmosphere.

[btoran]

All - Great info and advice. Thanks much. Excited to move ahead with the swap.

[btoran]

i installed the new carb and it's a beast. as others have said, it's like driving a different car and puts an entirely new smile on your face. that's the good news. now the bad......i'm having problems with the new carb and i'm not sure whether th eproblem is with the carb itself, the installation, or the installer (me).

the symptoms i'm getting are that the engine slowly cycles up and down (like from a vacuum leak) and there are terrific pops when decelerating. i'm not sure if these symptoms are related to each other or not.

here's what happended...

the new carb didn't come with a new gasket, so i used the old one and immediately disgnosed a vacuum leak by spraying carb cleaner around the base of the carb (which stopped the engine cycling up and down). so i bought some rubber gasket material and made my own gasket, but i still had the carb leak. finally, i bought some of the carb maker in a can and used it according to the directions, but i still have the vacuum leak around the base of the carb (which goes away temporarily with the carb cleaner).

one other thing i noticed is that the mixture screw seems to have very little effect on the carb, cranked all the way in, the engine will be stop, but after a turn, the engine stays running (with the cycling stuff going on). but turning it out further (like several turns) has no effect at all. not sure this is also related to the vacuum leak. The screw i'm speaking about is near the base of the carb and faces the driver side fender. it's in the bottom of this picture and turned most of the way out.



In reviewing all the previous connections, i noticed there is one electrical connection that i did not connect to the new carb. there is a place for it (under a large brass screw) but the receptical under the screw is a different size than on the old carb and the fitting is the wrong size. i was not able to trace the connector on the old carb back to its source as it disappeared into a bundle of wires. you can see the electrical connection on the old carb at the top center of this picture.



and here are two pictures of the distributor, in case it matters.





my next step was going to put the old carb back on and test it, but i thought i'd ask the experts here first.

so, here are my questions:

1. is the popping on deceleration caused by the vacuum leak?
2. is the mixture screw not having much affect caused by the vacuum leak?
3. what's the best way to fix the vacuum leak?
4. what was the electrical connection on the old carb for and is it needed on the new carb? if so, where do i find the correct fitting?

[lanciahf]

1. is the popping on deceleration caused by the vacuum leak?
Kinda, either the primary throttle plate or secondary throttle plate is open.

2. is the mixture screw not having much affect caused by the vacuum leak?
See above, if either plate is open you will never get a good idle mixture

3. what's the best way to fix the vacuum leak?
See if the plates are open first. Also get the right carb base gasket, I think midwest bayless has one.

[bradartigue]

When the mixture screw has no range it is usually because the primary idle jet is the wrong size. In your case it sounds like the idle jet is too big. If you go down a size you'll deliver less fuel and give the mixture adjustment more range.

I would order the next two sizes down and one up, save on postage.

As to the vacuum leak, I don't trust gasket former or other sealants. I'd remove all of it, clean it, and put cork gaskets on either side of the spacer. Or when you order the jets have redline or pierce or whoever you order them from send you a big old spacer with gasket material on either side.

[bradartigue]

Also FYI from a 14 year old thread (this part was from Jon Logan) on mirafiori:

Stock 34 ADF jetting typically is as follows:

Idle 47/90
Main 120/140
Air 145/180
Emulsion f11/f75

This should work really wel on an 1800 just like that.

On my 2L with stock pistons but 1800 head I found the following
was the best set-up:

Idle 50/60
Main 125/135
Air 160/180
Emulsion F20/F75

[btoran]

thanks. i ordered new gaskets today (a single, and a double with spacer) and will try it in a few days and report back.

out of curiosity, what was the electrical connection on the old carb for? was it for the smog controls or something else and do i need it?

[bradartigue]

thanks. i ordered new gaskets today (a single, and a double with spacer) and will try it in a few days and report back.

out of curiosity, what was the electrical connection on the old carb for? was it for the smog controls or something else and do i need it?

I'm not sure when it started - 79? - ADHA and maybe the 32ADF had a solenoid on the primary idle jet. Unless it had power (ignition switch ON) the jet was inoperable, the car would not idle/run.

[btoran]

well, my car runs, although not well. i'm not sure if that means i DON'T need the electrical connection.

it seems like both my old 32 adf and the new 34 adf have an electrical connection port in the same place (under the big brass screw in the middle of the picture below). however, the adapter that the electrical connection fits into once you renmove the screw are different sizes and the one from the old carb won't fit into the new one.



as a test, i'm thinking of putting the old carb back on and see if it needs that electrical connection. assuming it does (and the new 34 adf needs it too), where would i be able to purchase an adapter that goes under the brass screw?

[707kevin]

The Idle Stop Solenoind (Barrel shapped part with single wire attached) is not 'required'

When no power is applied to it, it BLOCKS fuel to the idle jet only.
When +12v is applied, it opens and fuel is allowed to the idle jet.

If you remove the solenoid you can modify it so that nothing changes with no +12v and fuel will flow at idle. Some people do this when the solenoid fails and no longer opens. (car won't start or idle)

The 34ADF in the photo with no Idle Stop Solenoid simply has a plug in the port, and fuel will never be cut off.

The idle stop solenoid is only there to prevent possible run-on after the key is turned off and no +12v is applied to the solenoid.

Run the 34ADF without a solenoid and forget about it