Weber IDA3C doesn't want to start

[BadToTheBown]

These are in a vintage 914-6 GT 2.4 race car...They are 40s and have run just fine since I bought it until this weekend when I was to going racing...first time working with Webers, so I have curve and books are on order now...

Initially it fires on the right cylinder, even kinda runs a little until it stalls out but that left carb and header are cold (not firing)...checked for spark (on left side) and it has spark, so then I turned to carb cleaner and ether and got it started and running and once warmed up it seems to run good BUT once it's cold again, forget it starting on left side...

Mallory fuel pumps, last owner re-plumbed to run carbs from either or both, I typically run off one of them now but will put back to pump for each carb later....

123 Distributor, good wires, plugs recent (were loose, I tightened them), MSD 6AL...

Don't know history of carbs but they've worked since I bought it until now, they are originals, not PMOs, re-jetted for our altitude (5000-6000 ft), once warmed up, they idle nice (I balanced them and set the idle about 1700 (cams will idle lower than this but I sometimes start in 2nd and it likes more idle starting this way)....

I'm worried it has sat too much with gas in them and something is gummed up but I'll defer to those of you who know these much better than myself, advice welcome....

[2svnhvn]

Has it been a while since the engine was run last? If so, sounds like carburetors need to be disassembled and thoroughly cleaned.
Enjoy!
Pete

[75 911s]

I agree with Pete. If it were mine, I would pull them both off, fully disassemble, inspect, and clean. It doesn't take that long maybe half a day to tear them down. There's some good tutorials on youtube by the old parts klassic guy. There's a way to test the hidden galley from the main jets up to idle jet using a drill bit and compressed air. I'd check those for sure.

I haven't heard of using two pumps, one for each carb. That's a new one for me, but maybe it's a track car thing.

Check the inline filters, fuel pressure etc. Show some pics of the setup too. That could help diagnose.

[BadToTheBown]

The 2 pump thing is for race and my gauge never moves of 3.5 lbs, so that's not the problem...think I need to look at the compressed air drill bit thing, any idea on where to find how to do that? Meanwhile, I'll start looking on YouTube and thanx everyone...

[Dpmulvan]

Originally Posted by BadToTheBown

The 2 pump thing is for race and my gauge never moves of 3.5 lbs, so that's not the problem...think I need to look at the compressed air drill bit thing, any idea on where to find how to do that? Meanwhile, I'll start looking on YouTube and thanx everyone...

Pm sent

[1QuickS]

Fuel Gallery Cleaning and Lead Plug Replacement
Fuel passageways are integral with the casting of the throttle body which are drilled and plugged during the original manufacturing process. These galleries are subject to blockage due to accumulations of dirt in the fuel or from dried fuel residues. They are also subject to corrosion induced blockage from contaminants in the fuel when combined with condensed water. Cleaning these galleries by using compressed air to blow through them in conjunction with using aerosol carburetor cleaners is recommended but sometimes a more thorough process is required. Additionally, there is one passageway per throttle bore that is "hidden" and requires a special procedure to clear it, see "Hidden Gallery Clearing Procedure" below.


Note that 40IDS3C throttle bodies differ from all others in that they incorporate additional fuel galleries to supply fuel for the High Speed Enrichment feature unique to these Webers.

If fuel gallery cleaning is warranted the following procedure will help in lead plug removal, gallery cleaning and lead plug replacement:
Lead plug locations:
• Seven on side of throttle body with mixture adjusting screws.
• Four on side of throttle body with accelerator pump
o 40IDS Webers have three additional plugs on this side.
• Top and bottom of throttle body have three each.
Procedure:
• Use sharp pointed awl (ice pick) to make a drill center in the lead plug.
o Note that some of the plugs on post 1967 throttle bodies are made from brass and are very exacting to center drill and even more difficult to remove, it is best to be satisfied with blowing these galleries to clear them.
• Drill through the lead plug with a 3/32" diameter bit; do not force the drilling, just let the bit make its own way and try to drill at a low speed.
• Use a #4, self-tapping metal screw and screw it into the hole in the plug.
• Use pliers to grasp the end of the screw and pull the lead plug from the gallery.
• The following methods may be selected for cleaning these passageways (McMaster-Carr is a good source for the items mentioned below):
o A selection of miniature brushes is now handy to scrub the exposed bores.
o Acquiring these drill bits will perform a better task:
 0.073” diameter x 3 ½” long with depth indicator set to be 2.45” (wrap tape around bit to create depth indicator)
 Used for both horizontal runs and for vertical run.
 0.103” diameter x 3 ½” long with depth indicator set to 2.05”.
 Used for vertical run only.
• Use a strong flashlight to illuminate the galleries and view from each end if possible, to assure galleries are clean.
• Install new lead plugs after cleaning is completed.
o The best and most convenient lead plugs are those used for pellet air rifles of 0.177 caliber.
o Use a flat ended punch and a small hammer to drive the lead plug into the end of the fuel gallery.
 Use tweezers to hold pellet in place when first setting the pellet if gallery is not vertical.
o Finish off with a radiused tip on a smaller punch, the radius will effectively trim off excess lead and make a nice dimple.
o Watch for shards of trimmed-off lead so they do not find their way into an adjacent and un-plugged fuel gallery or other opening when you aren't looking!
Hidden Gallery Clearing Procedure:
There is one fuel gallery for each throttle bore that appears to be "hidden" since it is not obvious to the casual observer. It is routinely blocked by corrosion, old fuel or dirt but cannot be easily cleared by soaking and blowing compressed air through the typical entry points on the throttle body. This gallery is the vertical passageway connecting the bottom of the emulsion tube well with the horizontal gallery the idle jet is installed into. If the following clearing procedure is not successful, then lead plug removal and manual cleaning of this gallery will be required to correct the blockage issue. The procedure for clearing the "hidden" gallery is provided below:

1. Drain fuel from float bowl
2. Remove the top cover from the throttle body (ten, 8mm self-locking hex nuts)
3. Note: High pressure air will crush brass fuel floats if introduced into the carb body via the vent pipes or fuel inlets.
4. Remove auxiliary venturi
5. Remove main jet assembly
6. Remove idle jet assembly
7. Remove main air correction jet and emulsion tube
8. Re-install auxiliary venturi but rotate it 180 degrees about its vertical axis and reinstall so that the wing with the spring blocks the fuel transfer port from the emulsion tube well
9. Place a 3/16” to ¼” diameter ball bearing into the port for the main jet assembly and re-install the main jet assemble and lightly tighten. The idea is to close the port at the end of the passageway where the main fuel jet is installed.
10. Use a rubber-tipped air nozzle and blow compressed air directly into the emulsion tube well keeping the nozzle tightly against the top of the carb to minimize escaping air
11. If the "Hidden Gallery” gallery is clear from blockage then air will easily escape from the bung where the idle jet assembly is installed
12. If Failure to pass air indicates a tightly blocked fuel gallery; that problem will require lead plug removal to correct the blockage.

Pictures show “Hidden Gallery” and location of lead plugs requiring removal to clean it. Note stepped diameters of each bore. It can clog since it is constantly filled with fuel and as fuel evaporates it can clog this gallery. The other fuel galleries typically self-drain after engine shut down so they are not as susceptible to clogging.
Red line in the sectioned float bowl indicates fuel level when properly adjusted, the width of the line indicates the maximum and minimum level tolerance range.

[BadToTheBown]

Thanx Paul, letting it sit with gas drying out was probably my mistake that led to this problem...I have gaskets and seals to order....most appreciated, shout out to Dave as well....

[tk32]

Originally Posted by 1QuickS

'dissected carbs photos'

Woah, more photos of surgically sliced carbs please!