Common Weber issues?

[VT_GT]

I've been fiddling with this Weber 32/36 DGAV carb for a few weeks now without much improvement. It came on the car when I bought it, and the previous owner said it never would idle after being installed.... it still won't.

At first I was thinking vacuum leak. So I removed both fittings from the intake, sealed and installed them, then plugged all vacuum lines (even ported lines coming from the carb). I also resealed the intake to head, and the carb to intake. For the carb to intake, I used the fiber gaskets and the order went intake>gasket>heat shield>gasket>phenolic spacer>gasket>carb. The carb base and spacer were slightly warped, so I resurfaced both to be flush, along with the intake.

It still won't run. When the choke is set (choke butterflies closed), it'll run just fine, but once they open up and it kicks off fast idle, it dies. The idle screw is bottomed out, therefore kicking it off the idle circuit and onto the main fuel circuit. I rebuilt it and it runs slightly smoother now, but still won't run when off the fast idle unless I constantly play with the throttle.

The only thing I can think of now is that the power valve (Holley term, not sure what Weber calls it) has a ruptured diaphram. Even if that was the case, it seems like it would want to run worse when airflow is restricted, like when the butterflies are closed. Any ideas? Sorry for the long post guys.

EDIT: Almost forgot, spraying starting fluid around the carb and intake sealing surfaces or vacuum fittings while running on fast idle doesn't change the RPM at all.

[jvandyke]

What jet sizes are in it? Maybe the idle jets are just way too small?

[VT_GT]

All stock jetting. 1.40 mm main jets (primary and secondary), .60 mm primary idle jet, .50 mm secondary idle jet. About ready to toss it out and just put a new one on, but I really hate replacing a carb that I rebuilt and was obviously pretty new to begin with (nothing really needed replaced when I rebuilt it).

[RallyBob]

Is the o-ring that seals the idle jet cover screw in good shape? I've seen this cracked and/or left off completely and it wreaks havoc with the tuning. Draws lots of extra air into the idle circuit!

How far out is the idle mixture screw turned? It usually needs to be somewhere between 1.5 to 2.5 turns 'out' from the seated position.

One last question...ignition timing set okay?

[VT_GT]

O-rings were replaced with the rebuild, and the old ones were still fresh and pliable. I've had the idle mixture anywhere from 0 turns out to all the way out with little to no change (other than smelling obviously richer). I'm almost 100% positive it's feeding almost completely off the main circuit.

Timing... that could be off. I set it per the service manual and didn't notice much difference. I need to clean the gunk off the viewing hole and flywheel so I can really set it. Maybe that should be the next thing to try.

One more note, at idle, fuel is dribbling from the auxiliary venturi. Not sure if that is a function of the throttle blades being open so far or not.

[lewdawg]

I've been experiencing the same problem on a 32/36 I am messing with on a GT for a friend. The carb had been kitted when I took it on. I opened up and took it apart and soaked it in carb cleaner and put it back together and adjusted the float level that was off but still no improvement. When I do get it fired off it runs rough and won't idle. As I close the choke butterfly it straightens out and runs smooth. I know its the carb because I have put another known good 32/36 on this car and it runs fine. Unfortunately the good carb is on another GT so its not a spare. The throttle butterfly doesn't seem to have an enormous amount of play that would cause it to suck air so I am at a loss as well. All the jets are of stock sizing and all seals appear to be good. What would cause a 32/36 to suck too much air???

[VT_GT]

Originally Posted by lewdawg I've been experiencing the same problem on a 32/36 I am messing with on a GT for a friend. The carb had been kitted when I took it on. I opened up and took it apart and soaked it in carb cleaner and put it back together and adjusted the float level that was off but still no improvement. When I do get it fired off it runs rough and won't idle. As I close the choke butterfly it straightens out and runs smooth. I know its the carb because I have put another known good 32/36 on this car and it runs fine. Unfortunately the good carb is on another GT so its not a spare. The throttle butterfly doesn't seem to have an enormous amount of play that would cause it to suck air so I am at a loss as well. All the jets are of stock sizing and all seals appear to be good. What would cause a 32/36 to suck too much air???

Lol, sounds like my problem exactly. Before the rebuild it would idle up when shooting starting fluid directly at the body of the carb, not near any gasket... but it doesn't do that anymore. There's gotta be something, but I'm not sure what it is.

[Paul]

Originally Posted by VT_GT I've had the idle mixture anywhere from 0 turns out to all the way out with little to no change (other than smelling obviously richer). I'm almost 100% positive it's feeding almost completely off the main circuit.

Well something MUST be wrong becuase the car shouldn't be able to idle if the idle mix screw it all the way in... as in fully seated. To begin with with the engine off, the throttle stop screw should be turned in (CW) 1 to 1-1/2 turns from the point of first contact... and the idle mix screw should be screw out (CCW) 2 turns from full seated. Screw it in all the way until it stops, don't over tighten, then turn it out 2 turns... this is the base line setting. Start the car and adjust the idle mix screw ONLY to the point of best, smoothest idle. Finally adjust the idle stop for idle rpms...

Best of luck

[73Manta72gt]

I sounds like a vacuum leak somewhere. I would post an ad on this site and see if someone would donate a solex carb they aren't using and see if another carb idles. Then you could focus on the problem with the Weber or the intake system. Also, you might want to drive down to Charlotte for Autofair Sept 15-16 There is a guy there that has a trailer full of carbs for sale He had a box full of 32/36 webers at the Spring Autofair. His contact info.

Arkansas Carburetor Cores
Marty Stouffer
479-452-0340 shop
479-646-1827 home
918-513-2079 cell

[VT_GT]

Originally Posted by Paul Well something MUST be wrong becuase the car shouldn't be able to idle if the idle mix screw it all the way in... as in fully seated. To begin with with the engine off, the throttle stop screw should be turned in (CW) 1 to 1-1/2 turns from the point of first contact... and the idle mix screw should be screw out (CCW) 2 turns from full seated. Screw it in all the way until it stops, don't over tighten, then turn it out 2 turns... this is the base line setting. Start the car and adjust the idle mix screw ONLY to the point of best, smoothest idle. Finally adjust the idle stop for idle rpms... Best of luck

That works if the it's feeding from the primary idle circuit, which the carb no longer is. With the throttle butterflies opened as far as it is, it exposes the transition slots and can therefore feed from the main circuit. When trying to close the butterflies back to a point that it feed only from the idle circuit, the car won't run. I might just have to get another one and toss it on there, just thought maybe it was a common issue I wasn't aware of.

Thanks a bunch guys.

[BQS4]

Just as a simple no cost thing to try, are all the screws to the top of the carb down tight?

[Paul]

I guess the idle curcuit could be partial clogged with a piece of grit... or the ICO is not connected to a switched 12volt source... or I don't know....

[73Manta72gt]

Something I remember from my weber install I had to add a few washers on the manifold stud,s because the nuts ran out of threads. The solex base is a lot thicker than the weber.

[N61WP]

Originally Posted by VT_GT One more note, at idle, fuel is dribbling from the primary venturi. Not sure if that is a function of the throttle blades being open so far or not.

Are you running an electric fuel pump? The Webers a re very sensitive to fuel pump pressure and will spill over fuel if it pumps the float off of seat. I had a 32/36 that worked perfectly with my pump, changed to a 38DGAS that would not idle without a fuel pressure regulator. I even swapped the float and stem and it made no difference, so each carb is different.

Jc

[VT_GT]

I did remember to add washers when installing the carb, although with the phenolic spacer I don't think I needed too... just extra insurance lol.

Too high of fuel pressure is another thing I'll check. It has a mechanical pump, but maybe it's putting out too much pressure for some reason. I'll throw a gauge on there and see what it comes up with. What's the stock operating PSI? 3-4?

[Cruz]

I think this a more common problem than we think. I have the same issues with mine. I have been playing with the jetting on 2 different carbs.... both rebuilt and little to no throttle shaft play, no vacuum leaks that I can detect, but it will only run just off the idle circuit with fuel dripping from the auxiliary venturi. idle stop screw crank all the way in ( entertained ideas of removing a coil on the stop spring) timing is set 5 deg advanced ele ignition, other than a really stretched timing chain i am at a loss also.
Cruz

[tekenaar]

Originally Posted by VT_GT I did remember to add washers when installing the carb, although with the phenolic spacer I don't think I needed too... just extra insurance lol. Too high of fuel pressure is another thing I'll check. It has a mechanical pump, but maybe it's putting out too much pressure for some reason. I'll throw a gauge on there and see what it comes up with. What's the stock operating PSI? 3-4?

Stock pump? . . . stock pump is self-regulating as pump diaphragm has no mechanical connection to central actuating rod. There is a spring on each side of the pump's mounting flange so that when regulated pressure is reached inside pump, the diaphragm is held stationary by fuel pressure, i.e. no longer 'pumps', even though central push rod continues to cycle, but against just the flange spring, not the diaphragm itself. Pretty neat, eh!

[Cruz]

thanks for catching that! Tekenaar

[anastosmotors]

Two weeks ago we had to adjust John`s Gt for idle problems when
it was warm. We had to adjust the secondary throttle plate stop adjust
screw. You can access it from bottom of throttle body with
screwdriver tip left back of carb. (next to #3 spark plug ) It is
hidden at the bottom of carb.

Pete

[tomking]

That is a good point Pete. If the secondary is open just a little bit it will pull air and with the air it will pull fuel. Means it idles without being controlled by the idle circuit. At least I think that is what it means( I am learning too about carbs, both Solex and Weber and how they work). I too was having difficulty getting my idle to where it was supposed to be. Then I reset the secondary throttle plate and CONTROL!! Plus I had already used the specified set up by getting it .002 open with a feeler gauge but that actually made it too far open. I set the stop the next time by magnifying glass to where the stop screw stops the plate instead of plate hitting venturi wall and sticking closed.
Pete is right on that it should be checked.

[VT_GT]

The secondary suggestion is another good thing I'll look at. When I had it off, I just adjusted it so that the screw just barely made contact. Maybe it's open too far, I'll have to check.

[Bill Hoffmann]

I know this is hard to check with an engine that won't idle, but the throttle stop screw should be set for 6" of water in an open tube manometer connected to the vacuum advance port, as described in the service manual. However, as a less precise check you can connect a standard vacuum gauge and make sure the needle just barely moves - less than 1" of mercury should be seen. Otherwise you are too far into the transition ports. There are good instructions for setting up the Weber at the Racetep web site also.

Besides that, the other things I would check have been mentioned - warpage of the base or sloppy throttle shafts for vacuum leaks, and the secondary throttle plate too far open that Pete mentioned. Have you disconnected the distributor vacuum canister connections? I would, until you can get it to idle, just to eliminate one variable.

That reminds me. I bought a Manta real cheap once that had almost the opposite problem. It would idle all day but as soon as you tried to accelerate it would die. I barely was able to drive it the short, mostly downhill distance home. To make a long story short, I found that someone had replaced one of the screws for the distributor cap hold-down clips with a screw that was too long. As soon as the timing advanced, the points would short out on this screw! I replaced it and burned some rubber leaving the driveway.

[VT_GT]

Put on a new carb and all is good. Not sure what the deal is with the other one.

Just got done with a 250 mile drive and the car performed impressively. After sitting over 5 years, all it took was new fluids, ignition, and a carb and it made the cruise without a hitch. Got 25 mpg too, and didn't use a drop of oil.

[tekenaar]

Originally Posted by tomking That is a good point Pete. If the secondary is open just a little bit it will pull air and with the air it will pull fuel. Means it idles without being controlled by the idle circuit. At least I think that is what it means( I am learning too about carbs, both Solex and Weber and how they work). I too was having difficulty getting my idle to where it was supposed to be. Then I reset the secondary throttle plate and CONTROL!! Plus I had already used the specified set up by getting it .002 open with a feeler gauge but that actually made it too far open. I set the stop the next time by magnifying glass to where the stop screw stops the plate instead of plate hitting venturi wall and sticking closed. Pete is right on that it should be checked.

Throttle blade clearances are set with round, not flat!!, gauges . . . like spark plugs and points!

. . . and here's why:

[tomking]

I am learning Otto.