Topic: Help me rebuild some RC Webers? Or, just watch..some people just like to watch.

[Bill/BentON Racing]

Jaguar,  yes those came from you. Maybe you know what cc etc they came off of?  Bill

[Greggo]

The pump and rod came out in one piece. 
Scottly, your pics were instrumental in helping me get the pump rod out...I could see from those that it could take way more downward force than upward pulling...so, I tapped it with a hammer from the top, and it budged.  Thank you!

The only thing left is the pump bypass jet, but I can't get it out...it's completely stripped.


Here's how bad the pump rod looks..

[jaguar]

Jaguar,  yes those came from you. Maybe you know what cc etc they came off of?  Bill

Cam off a 73mm bore motor.

[Bill/BentON Racing]

Jag, thanks. They'll probably have 32mm chokes in them, Bill

[BPellerine]

could try hot water bath to get spill jet out,carb may expand before jet??bill

[scottly]

That spill jet is going to be tough, since it's so deep in the carb. Perhaps one of those tools that has an oscillating blade could be used to cut the slot deeper? The only alternative would be a left-hand drill bit; one of the things about brass is that it tends to be a "sticky" material when drilling. Also, there is a small flat piece that fits in from underneath to retain the ball, which may help jam the bit? I'll get some pics.
Did you get all the parts out of the throats? The chokes have the size either stamped or cast into the opening. Notice the 30 near 3:00 in this pic:

 

[Greggo]

That spill jet is going to be tough, since it's so deep in the carb. Perhaps one of those tools that has an oscillating blade could be used to cut the slot deeper? The only alternative would be a left-hand drill bit; one of the things about brass is that it tends to be a "sticky" material when drilling. Also, there is a small flat piece that fits in from underneath to retain the ball, which may help jam the bit? I'll get some pics.
Did you get all the parts out of the throats? The chokes have the size either stamped or cast into the opening. Notice the 30 near 3:00 in this pic:

 

Aha!  So that is what you've been calling the choke.  I did get those out, and they have no numbers whatsoever on them...

As for the spill jet, I'm taking the carb up to my dad's shop to see if the better tools, and two other mechanic's brains there can help.

[scottly]

The choke in Weberese is the venturi in Amurican, and the piece that fits between the choke and the stack with the bomb-sight in the middle is the auxiliary venturi in Web-speak, or booster venturi to us.
The stamped marks are hard to read, especially on the aux.
Any luck with the spill valve? I've got an idea, but it's only a last resort, move werry, werry carefully type of thing...

[Greggo]

Wow...I guess it just took some different lighting to see them.  The chokes are 34's, and the auxiliary venturis are 25's.

I've resigned myself not to touch the spill valve until I can bring it to the shop, where better tools live.  I think there is an impact driver bit, or extension long enough to reach into there.  I think it just needs just one good thwack to get it going...it's just having the right bit to get way down in there.  What's your idea?

[Greggo]

How concerned should I be about the starter valve I damaged?  I've seen some for sale at under $20...should I just grab one?

Also, I'm still trying to free one of the pump demand valve balls.

[BPellerine]

that is a strange setup,big chokes and small aux.most of the time you do not use the start circuit ,but no sense putting them back together if you are not comfortable with what you have.

[scottly]

Try the impact driver first. Use a 1/4" drive extension and socket for the bit. Use an impact bit with a .045-.050" thick tip, to match the slot. Give it few taps without an twisting motion to get the tip firmly seated. Make sure you support the underside of the jet in the black area in this pic, or you may punch out that area; as Bill said before, the zinc alloy is brittle.

[scottly]

Regarding the start valve, as long as the bevel on the bottom is good, and it slides freely in it's bore so the spring holds it shut, I wouldn't bother replacing it. I don't think you have the mechanism that operates them anyway.
Are you sure the aux are 2.5? 4.5 are the most common.
Lastly, the carb I have been taking pics of has a damaged top, a dented float, and some missing parts. If you get into a bind, or just flat give up, I'll sell you the main body, stripped of most of the brass, for $50 plus shipping.

[Greggo]

Regarding the start valve, as long as the bevel on the bottom is good, and it slides freely in it's bore so the spring holds it shut, I wouldn't bother replacing it. I don't think you have the mechanism that operates them anyway.
Are you sure the aux are 2.5? 4.5 are the most common.
Lastly, the carb I have been taking pics of has a damaged top, a dented float, and some missing parts. If you get into a bind, or just flat give up, I'll sell you the main body, stripped of most of the brass, for $50 plus shipping.

Definitely a 2, not a 4 on the aux. 4.5 auxiliaries. I may take you up on the offer for the carb body..I'll let you know.

The starter valve is okay on the bottom, and will definitely slide freely once cleaned. 

I'm gonna be REEEEEEAL careful with the pump bypass jet.

[Greggo]

Does anyone have a spare pump rod spring?  Mine was busted in two when I pulled it out.

I see a Czech seller on ebay with new parts, including chokes...is there a supplier stateside? I'm going to pick up a jet kit from Redline. Does anyone have a set of 30mm chokes I could buy?

[Greggo]

Regarding the start valve, as long as the bevel on the bottom is good, and it slides freely in it's bore so the spring holds it shut, I wouldn't bother replacing it. I don't think you have the mechanism that operates them anyway.
Are you sure the aux are 2.5? 4.5 are the most common.

Definitely a 2, not a 4 on the aux.  I may take you up on the offer for the carb body..I'll let you know.

First off, I was wrong again...the aux's are 4.5's, not 2.5's.  I'm not great with tiny numbers.  Will the 4.5's likely be OK for my application?

For the starter valve mechanism...these?

[Tintop]

As for Weber parts Stateside, I've found these guys to be very helpful - Pierce Manifold http://www.piercemanifolds.com/

4.5's will work fine on the street, kind of like F11 emulsions, in that they work in a lot of situations.  As for starter valve stuff, just junk it all, and fit a blank-off plate.  When the carbs are 'right', a couple of twists of the throttle (accel pump ) will be enough to start.  Worked for my Elan, Seven, Cortina (race), and sidecar.

[754]

Parts shown are enrichners.. I used to put cable across the two, with an end on it, like your throttle cable upper end...you can use a 2.00 bicycle cable.. Have about 2 inches hanging out.
 Prime to start, then pull on the knob once running, to give it choke for a minute or two.
 You can build a better setup,  so you can have settings. Like 1/2 or 1/3 on.

[Greggo]

Scottly, I need that spare body, and a spare spill jet if you have one. This one did not come out.

[scottly]

OK, time for Plan B. Take a 1/4" hex socket, and grind the outer edge at an angle, leaving a sharp edge on the inside. Drive the socket down over the spill valve, by tapping with a hammer, while firmly supporting the underside of the body. The sharp edge will peel off brass, creating flats. I tried it with a piece of brass turned to the same OD as the valve, and with the socket driven about 1/16" over the valve it was good up til about 55-60 inch pounds of torque. I also found the if the angle was sharper, it took less force with the hammer to cut the flats, but the socket itself cracked at about 60 inch pounds.

[Greggo]

We went through a few plan B's over the course of 90 minutes, and eventually the jet died and sheared where it threads into the body. 

The screwdriver slot on the jet in the other carb isn't much better. 

[Bill/BentON Racing]

Gregg, I knew them carbs were trouble as soon as I laid my eyes on them. So if Scottly will sell you a body that's great. I also have one I use for parts, if needed after Scottly's offer, it will be available, you will have a running set of Webers! G'luck,  Bill

[754]

Look around for someone that does bolt or tap extraction.. They will use a disintegrated, or EDM.
With EDM, they simply burn a hex shape hole inside the fastener, then use Allen wrench.
If you can find one nearby, would be worth looking into.
 I suspect some heat would be needed to get the brass to lose its grip.

[Greggo]

Gregg, I knew them carbs were trouble as soon as I laid my eyes on them. So if Scottly will sell you a body that's great. I also have one I use for parts, if needed after Scottly's offer, it will be available, you will have a running set of Webers! G'luck,  Bill

Thanks Bill.  I won't give up.

Look around for someone that does bolt or tap extraction.. They will use a disintegrated, or EDM.
With EDM, they simply burn a hex shape hole inside the fastener, then use Allen wrench.
If you can find one nearby, would be worth looking into.
 I suspect some heat would be needed to get the brass to lose its grip.

I didn't throw it in the scrap pile yet...will see if there is someone local who would give it a shot.  Thx.

[scottly]

The minor diameter of the threads is about .170", and the ID in the threaded area of the jet is about .130", so there's not a lot of meat. The flat piece which retains the plastic ball can be punched out through the bottom of the jet; there is enough room under the jet. Were you able to identify the size? The number corresponds to the tiny hole on the side. Sorry, but I don't have any spares that I can part with.
I may have a spare pump spring, but you need to identify which springs you have. Measure the wire size and number of coils. You may also want to take the other carb apart before I send the parts in case you find you need more bits.
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