Weber DCOE 18 40 service kit question

[Mikez31ss]

I bought "comprehensive service" kits from eurocarbsltd for my Webers. I don't have much experience with carbs but there aren't that many parts compared to a Holley 4v rebuild so this looks doable.

The carbs seem to be adjusted well now so I plan to check each adjustment screw and write down the number of turns so I can get it all pretty much back where it is now.

I need to set the floats but that looks easy enough. I have a syncrometer so I plan to check the carbs for synchronization too. I may have to change a few adjustments if they're off so I'm a little leery about that.

Any advice or gotcha's I need to watch out for?

[Mikez31ss]

Ok how about just telling me if I'm on the right track here

I wanted to ID the parts in the kit and the basic carb parts before I get started. I think I have everything pinned down except a couple of things.

The spring: it's the internal throttle return spring?

And two small metal washers...I think they are part# 49 in the diagram but called (pump jet) gaskets instead of o-rings?

And finally...there are 7 small o-rings and 2 larger ones. I know there is one for each idle mixture screw and one for each pump jet and two for the throttle spindle. I won't be using those if I have to disassemble the throttle to replace them.

I can't find any more o-rings in the parts list or my manual.

 

 

 

I know I'm playing with fire here.

[Mikez31ss]

I finally got started. Two odd things I noticed. On two of the carbs, gas squirted out when the pump was depressed. The other one...nada. It had gas in the bowl too /shrugs.

The other thing...the needle valve seating had no "gasket" as the manual calls it. I was hoping to ID the new one by looking at the old one. It's got to be the big silver one in the pic above. I'll check the next one to see for sure.

Also I'm thinking I should leave the spindle assembly alone since it seems okay and I've heard it's not something to be messed with unless it's definitely got problems. True?

Also...is the auxiliary venturi retaining screw hidden under a brass plug? The manual isn't clear on that.

[Konish]

Ok how about just telling me if I'm on the right track here

I wanted to ID the parts in the kit and the basic carb parts before I get started. I think I have everything pinned down except a couple of things.

The spring: it's the internal throttle return spring?

And two small metal washers...I think they are part# 49 in the diagram but called (pump jet) gaskets instead of o-rings?

And finally...there are 7 small o-rings and 2 larger ones. I know there is one for each idle mixture screw and one for each pump jet and two for the throttle spindle. I won't be using those if I have to disassemble the throttle to replace them.

I can't find any more o-rings in the parts list or my manual.

 

I know I'm playing with fire here.

 

The small, itty, bitty washers mount on the pump jet shaft (the end that goes down into the carb). My original AL washers were literally crumbling apart. The larger o-rings are supposed to be for the accel pump brass plug, but they fall apart after a month or so anyway, or get so cracked they are useless for sealing anything.

 

The large single washer is indeed the "gasket" for the needle jet...my originals did not have one so I think they must have added it later to a newer series of DCOE...can't hurt to use.

 

To pull the accelerator piston out of the bore, just pinch the retainer a bit with some dull needle-nose pliers. After the retainer comes out, the piston and shaft assembly can be removed. The piston can be removed by pulling the spring up on the shaft and working the piston off the end of the shaft (which is basically a hook to retain the piston "wrist pin")...do NOT drive the pin out out of the piston. Also, if the retainer ring is loose upon reassembly, just use a standard tip screwdriver as a mini wedge and force the arms apart a bit...don't honk down on it or you'll ruin it. Essentially, it should tight enough to snap into place.

 

Also, don't use the float setting method listed on any website and/or the service manual...I could never get the float height right using this method. Lots of guys measure the actual fuel in the main jet bore by using a straw or plexiglass rod...google it and you should find the method. I think the right number is 2mm below the main jet bore spillway.

 

To get the main throttle spring out, I just unhooked it from the throttle shaft arm and pulled up on the exposed part in the carb...came right out. To reassemble, it's easier to hook the spring to the arm first, pull the hooked of the spring on the top of the carb far enough out to mount the retainer ring and let it "seat" back into it's counterbored hole.

 

If you do remove the spindle, note that the butterflies mounting screws are staked (peened) on the backside. I powered through mine and thy cmae out fine but most guys will take a small dremel and grind down the peened part. If you do this method, you *must* put a shield in the bore in case your dremel slips of the collar makes contact with the main bore...both are bad obviously.

 

The newer aux venturis use a small grub screw to hold them in place...the older ones used a small spring loaded detent. Basically, you 'll need a long, soft wooden dowel and push them out form the throttle plate side...pulling them out is really, really hard after years of being stuck in there. BE CAREFUL and don't force them from one position...move the dowel around the perimeter of the aux v and try not to use the center section. If you have to use the venturi arms for a pushing surface, use the base of the arms. Mine took some doig, but afterwards, I could pull them out with my fingers.

 

If your spring detents and your aux v's are good, don't worry about removing the brass plug...it's no big deal if it comes out on it's own either, but you don't need to force (or drill it out). Just push the aux v's back into the bore until it "snaps" into place. The grub screws just suck as they are too shallow and have a coarse thread which cause them to vibrate out unless you locktite them in or use safety wire. Besides, it's too easy to tighten them to the point where the crush the venturi. Also, the newer DCOEs use a grub screw to hold the chokes in place as well...which isn't present on the older models.

 

Good luck. Oh, and I find Webers to suck in ways stuff should not suck. I finally went with Mikunis and everything has been roses...tuning, quality control, tolerances, everything is just better. My carbs idle at a rock steady, 900 rpm, don't buck or spit and the transition is like butter...no nose-dive here. And before anyone says anything, the Mikuni 40s are almost 15 years old (rebuilt), my DCOEs 45 152s were brand new and my DCOE 40s 18s were about 15 years old (rebuilt). The 18s weren't bad, but they didn't perform anywhere near as nice as my Mikunis. I know for sure that people love their Webers and have been able to tune them to perform superbly, but not without a ton of work. Seriously, my Mikunis were almost too easy after my Weber experience. Just my PERSONAL opinion..not trying to start a flame war.

Edited August 2, 2010 by Konish

[ZR8ED]

Good post above. Good advice. As for the throttle shafts, if it "ain't broke" leave them alone. They rarely need much work, and it is really easy to screw them up.

 

I have never heard of setting floats that way, I always used the manual and took my time. Accuracy counts when it comes to webers. 1mm CAN make a difference.

 

Flats spots are common with webers...just not a single one I ever setup..flat spots are all about the emulsion tubes.

 

I agree that mikunis are easier as they are a newer design with lots of improvements over the webers.

 

I prefer webers though.

[Mikez31ss]

That is really useful info. Thanks guys. And Konish...I can't tell you how much I appreciate you taking the time for such a detailed post. It answered questions I would have asked if I'd thought about them. You and Adrian should be in the newb helper hall of fame

I had to google for this:

"One complaint folks have about the Weber carb versus twin SUs is a "flat spot" or dead zone, or bog, on throttle..."

My car doesn't have that problem so I guess the emulsion tubes are right. I don't know much about carbs obviously, so if I can get them back to the way they were before performance-wise and eliminate the leaks I'll consider it a big win.

[Zmanco]

Double check that the inlet needle/seat combo in the kit matches what you're taking off the carbs. When I rebuilt mine I didn't notice that those in the kit were smaller and it took me a long time to figure out why I had a WOT high rpm miss ...

[Mikez31ss]

Double check that the inlet needle/seat combo in the kit matches what you're taking off the carbs. When I rebuilt mine I didn't notice that those in the kit were smaller and it took me a long time to figure out why I had a WOT high rpm miss ...

Thanks man...I checked. The old ones were 200...new ones are 175. I'm gonna go ahead and go with them. On that note here are the numbers I have so far.

Main jet 130

idle jet 45 ...and F9? Not sure about the last two characters

Emulsion tube F11

air correctors 165

Probably meaningless w/o knowing my cam specs.

 

I'm still on the first carb but it's coming along. Hope to get an earlier start tomorrow.

 

I haven't been able to get the accelerator pump jets out yet. I thought they'd come right out like everything else has. Any tricks? The manual just says "remove". Doesn't say how

The only o-rings I've found so far are under the accelerator pump jet screws.

According to the manual there are supposed to be o-rings & conical washers for the idle mixture screws but there aren't any on mine.

The kit has new style idle mixture screws but they are quite a bit longer than the old ones. I'm skeptical about using them. Any thoughts?

Also...one idle mixture screw was 1 turn out and the other was only 1/2 turn out. Big difference.

I'm trying to take a lot of pics in case the next newb that is crazy enough to do this needs some help.

http://67.18.219.83/image_hosting/web_pages/Mike88se/images/240/webers.htm

Here's a pic of the idle mixture screws:

 

[ZR8ED]

The screw on the left has a much more gradual angle to it. The big difference is that it will take more turns to get a similar effect compared to the one on the right. In other words they are less sensitive to adjustment, or another way to look at it is they can be more precisely tuned.

[Konish]

 

I haven't been able to get the accelerator pump jets out yet. I thought they'd come right out like everything else has. Any tricks? The manual just says "remove". Doesn't say how

 

Once the bore is stripped of everything...choke and aux v, you'll see a little brass tube sticking out form the top. That is the bottom (sprayer end) of the pump jet. *Very* carefully take a soft wooden dowel or stick and push the jet up and out of the bore. Trust me, pulling from the top is impossible and if you're washers were as corroded as mine, it'll take some doing even with the stick. When mine did let go, they popped up and out of their orifice.

 

Also, forgot to mention. If you pull the start circuit pistons out of their bores be aware that when you pull the retainer rings (top of carb, one for each starter piston), it is spring loaded and will shoot the brass nipple, spring and reatiner ring all over hells half acre...ask me how I know. The pistons will probably be stuck if the circuit isn't working. I used a lot of heat from a propane torch and lots of penetrating oil to get them to pop out. Of course, you'll need to pull the lever assembly off the back of the carb, disassemble and clean that including the screen. To remove the retainers, just push down on the brass nipples as they are spring loaded and use a soft brass implement to simply pop them up and way from the carb

Edited August 3, 2010 by Konish

[Konish]

Good post above. Good advice. As for the throttle shafts, if it "ain't broke" leave them alone. They rarely need much work, and it is really easy to screw them up.

 

I have never heard of setting floats that way, I always used the manual and took my time. Accuracy counts when it comes to webers. 1mm CAN make a difference.

 

Flats spots are common with webers...just not a single one I ever setup..flat spots are all about the emulsion tubes.

 

I agree that mikunis are easier as they are a newer design with lots of improvements over the webers.

 

I prefer webers though.

 

I tried the float method about 1/2 dozen times and could not get the level right as sighted down the main jet bore. I then weighed my floats and they were all different. Instead, s et up a rig with a thick plastic straw and put a slip collar around it (essentially a much shorter piece of the the straw with a small cut down it's length and mounted around the longer piece). By sighting down the straw, I could see where the surface tension of the gas would change and it was very precise. Then, once you pull the straw out, you can measure from the collar down to the end of the straw to see where your float level is...I think the magic number was 25mm down the bore which puts the gas 2mm below the spillway. Using this method, I got the gas level in each carb to measure exactly the same (well, how about within a tenth of a mm from each other)...

[Mikez31ss]

Once the bore is stripped of everything...choke and aux v, you'll see a little brass tube sticking out form the top. That is the bottom (sprayer end) of the pump jet. *Very* carefully take a soft wooden dowel or stick and push the jet up and out of the bore. Trust me, pulling from the top is impossible and if you're washers were as corroded as mine, it'll take some doing even with the stick. When mine did let go, they popped up and out of their orifice.

 

Also, forgot to mention. If you pull the start circuit pistons out of their bores be aware that when you pull the retainer rings (top of carb, one for each starter piston), it is spring loaded and will shoot the brass nipple, spring and reatiner ring all over hells half acre...ask me how I know. The pistons will probably be stuck if the circuit isn't working. I used a lot of heat from a propane torch and lots of penetrating oil to get them to pop out. Of course, you'll need to pull the lever assembly off the back of the carb, disassemble and clean that including the screen. To remove the retainers, just push down on the brass nipples as they are spring loaded and use a soft brass implement to simply pop them up and way from the carb

Thanks Konish. I'll think about that float setting method.

 

I did manage to get the pump jets out...I just pulled harder. But carefully lol. Everything I'm doing is carefully. The aluminum washers were a little hard to remove. They were pretty much stuck to the jets. I'm glad I didn't cut my fingernails before starting this. They came in handy today lol.

I'm not using the starter circuits so I'll just leave those alone.

The aux venturis have a number 45 on them and the chokes have 30.

The first carb is pretty much done. I just need to set the float and recheck everything. I think the other two will go much quicker. Maybe they will have the o-rings and/or washers that this one didn't have. If so I'll go back and correct the first one.

I did have some comic relief. After getting everything back together I noticed a brass part left in the box I stored the carb in last night. Oh **** moment. After checking a couple of jet assemblies I looked at the part closer and remembered I had some MSD parts stored in the box before.

Recognize it?

 

 

Scott...ZR8ED...it is Scott right? I talked to you a couple of times at z31.com long ago. Reading between the lines (or not) you're saying the newer idle screws are better. Sounds good as long as I don't puncture the carb wall with those sharp ends

I don't suppose any of those mystery o-rings would be useful on the mixture screws?

 

This one looks much better than the others.

 

[Mikez31ss]

I'm pretty much finished. Never found any more o-rings or washers. Must be for the throttle spindle or starter circuit or a different model DCOE. Still need to set the floats and do a final check.

I think these last two aux venturis are screwed. Anybody have a couple of extras lying around?

 

[Konish]

I'm pretty much finished. Never found any more o-rings or washers. Must be for the throttle spindle or starter circuit or a different model DCOE. Still need to set the floats and do a final check.

I think these last two aux venturis are screwed. Anybody have a couple of extras lying around?

 

They are screwed...looks like from a back-fire. I had 2 like that on my DCOE 40s. What's more is that when you order new ones they'll be the newer kind held in by grub screws, which means you'll have to drill out the brass plug and tap the holes for them. I tried like crazy to find the old school kind but no such luck. Just remember to order some grub screws along with your aux v's.

[Mikez31ss]

Thanks for the headsup but I've already ordered the venturis. I'll have to improvise on the screws.

[Mikez31ss]

Still waiting on the venturis. I'm hoping I can find a way to modify the new ones to use that spring part from the old ones. We'll see.

I decided to make the heat shield more manageable. I folded part of it back under and added a sheet of phenolic material to it near the header. Hopefully it will insulate the carb bodies better and open up some air flow.

 

 

I'm wondering if adding some aluminum heat shielding between the header and the dizzy would be a good idea. I stuck a piece of aluminum angle in but I haven't figured out how to attach it.

 

[ZR8ED]

Yes that is me.

 

As for the screws, yes they will allow finer tuning. Your old settings (number of turns) will be useless now, It will take more turns to make the same effect as compared to your old ones. When tuning/adjusting, you will likely make full turns as opposed to 1/8 or 1/4 turns to notice a change.

[Mikez31ss]

Yes that is me.

 

As for the screws, yes they will allow finer tuning. Your old settings (number of turns) will be useless now, It will take more turns to make the same effect as compared to your old ones. When tuning/adjusting, you will likely make full turns as opposed to 1/8 or 1/4 turns to notice a change.

Thanks I'll keep that in mind.

I got the new aux venturis and they are indeed the new type requiring a set screw. I can order two set screws from Pierce but paying $10 + $5 shipping for a couple of set screws is hard to take.

Konish...I'm curious if you considered slotting your new aux v's to use the springs from your old aux v's?

And since I don't know the size of the set screws I have to ask if the entire brass plug is supposed to be drilled out and the carb body tapped for the screws? Or do you drill an appropriate size hole in the brass plug and tap the brass?

Sorry if these are newb questions but money is tight and I can't afford to screw up.

And to answer the obvious question...no I probably shouldn't be owning a car like this on my budget lol.

[Mikez31ss]

I decided to go ahead and try modifying the new auxiliary venturis to accept the springs from the old AV's. It was risky but it worked

The new ones slide in and snap into place just like the old ones did.

Here are some pics and a link to how I did it.

 

click

 

 

 

[Mikez31ss]

Got started reinstalling the carbs tonight. Big difference in looks.