Help - cannot get weber needle valve plug off

jchatfield · 05-13-2004, 08:11 AM

I am in the middle of rebuilding my Weber 40IDA's and I cannot get the needle valve plug off - some dufus (me) overtightened them when adjusting the float level 2 years ago.

Should I just leave it be and skip this part of the rebuild? The float levels were fine before the rebuild.

I can probably get them off in a vise, but I am afraid of damaging the float bowl cover.

What should I do?

Also, there are not fuel filter screens on the fuel inlet banjo bolts? Are not there suppossed to be? If so, I guess I should wait to get those before reinstalling the carbs?

Grady Clay · 05-13-2004, 08:22 AM

Jim,

Now is the time to solve problems like that.

Get a like-new condition good socket (SnapOn) and use an impact wrench while holding the carb top in your other hand (not vice.) Make sure the wrench is square on the hex and has as much purchase as possible. Press down hard.

Yes, the banjo bolts should have the screens. You can put them on later.

Best,
Grady

jchatfield · 05-13-2004, 08:25 AM

Grady:

I don't own an impact wrench, and I have tried to hold the housing. the only thing I can use is the vise. is this safe or is the housing too delicate? I think it is too delicate.

Thanks,

Jim

yelcab1 · 05-13-2004, 08:43 AM

You can use the vice, providing you pad it enough with rags and stuff. The idea is to counter hold the carb top against a padded hard edge while you turn the valve with a socket-ratchet. So, do not squeeze the vice hard, just loosely hold it in place and use the vice like another hand.

Grady Clay · 05-13-2004, 10:19 AM

Jim,

Yes, it is too delicate.

Take it to a shop that has a good impact wrench.

Since the hex is so short, the main issue is having the socket cam off the hex under load and round off the corners of the hex. Then you are suddenly in a worse predicament.

The key is having the best 6-point socket possible, forcing it straight on the hex, and using a good impact wrench at relatively high air pressure (lube the impact wrench and make absolutely sure you are in the un-screwing direction.) Even though you are un-screwing, you need to apply a lot of hand force keeping the socket on the hex. You want it to come loose at the first full impact. BAM, its off.

If the hex is rounded from much use, replace it now.

If the hex gets rounded there are several remedies. The one I prefer is to take a 19 mm (across the flats) nut and drill six 1/8” holes around the perimeter. Using the drilled nut as a drill jig, drill six holes in the N&S cap. Tap in six 1/8” roll pins through both. Now you have a good 19 mm hex to work with. You can even epoxy it in place. Attack again with an impact wrench as above.

Temperature differential can also help. Warm everything up to less than 150F and then put some dry ice on the cap. Too much heat can damage the N&S. I also don’t trust the high temp properties of the metal used in Webers.

You can always Drimmel the perimeter flange off the cap and it will unscrew by hand.

Let us know how it goes.

Best,
Grady

911pcars · 05-13-2004, 12:17 PM

The needle and seat assembly are below the plug. To replace it, the plug has to come off. As pointed out, the hex flats aren't very tall; not as much surface area for a socket to grab onto.

You don't want the socket to slip off with an impact gun at full torque. Here's my suggestion: Take the socket (6-point) and grind flat the leading edge of the socket opening. This should eliminate any chamfer or bevel on the leading edge and allows the internal flats of the socket to further engage the flats of the brass plug.

For a good holding fixture, I would assemble the top to the throttle body, then temporarily bolt it back on the engine. Access is not good with an impact gun in this situation, but a 1/2 extension handle should be able to loosen it. Don't let the socket slip off.

Best wishes,
Sherwood

Grady Clay · 05-13-2004, 02:20 PM

Sherwood, right on. Most don’t like modifying their tools but I do. I have that socket ground on its face. It is an industrial impact socket from SnapOn with their “Flank Drive” which gives slightly better round-off protection. Help me, is it 16 mm or 18 mm? The only thing with that wrench size in an early 911.

I still rather use an impact with the part held in my hand. I’m just not willing to risk bending any of the carb sections with high torque. Webers are such flimsy pot-metal. I only might consider it if they were PMO aluminum carbs.

If the hex gets rounded off, another solution is to take a flat file to it. You can reduce the hex size to the next mm size or to a SAE size. In that case you want the socket to be a press-fit or tighter. In the process you can file into the flat portion of the cap and gain more purchase on the new hex.
Once the cap hex has been rounded off it is just junk and you are trying to save the carb top.

Jim,
Don’t feel bad that this happened. The gasket under the cap tends to stick more or less, depending who’s gasket kit you use. You are also balancing it being too tight and difficult to get off against too loose and possibly leaking. Difficult when you only do it once every few years. Even professional mechanics occasionally have to deal with this problem.

Another possibly suitable way to hold the carb top is to get a piece of scrap 2x6 soft pine and drill a large clearance hole for the N&S. With two people, one can holding it down by hand to a bench and the other operate the impact wrench.

Best,
Grady

jchatfield · 05-14-2004, 08:19 AM

Thanks for everyone's input. I took it toa shop with an impact wrench and that failed, or I should say that after two failed attempt, I bailed for fear of damage.

I went home, put it in the vice wrapped with rags, spayed everything with liquid wrench, waited 1/2 hour. I then filed the edges of the rounded off brass nut and pounded a six face 15mm socket on and used the big half inch ratchet for leverage. Off they came!

I was pretty careful not to warp the covers, butvthe one seems to have a slight gap to it. Who knows, it may have been there before, and I'm pretty sure the gasket will take care of this very slight imperfection. If not, I can file the mating surfaces to a perfect match.

Thanks for all your input. BTW, I just spoke to Richard at PMO and he suggested the fiber gaskets over the metal ones, which tend to put me in the prediciment from which you all helped me escape.

Thanks again!

Jim