Awhile back, Randy (RoadGlue) gave me the opportunity to rebuild his Weber 40 IDFs, and I thought I'd take the opportunity to document the process. I'm also going to try give a little insight on some of the tips and tricks I have learned along the way. Keep in mind, this thread is a work in progress, as Randy and I are still tracking down some of the parts these carbs were missing.
Now, I understand for most people, the process is fairly straightforward and many of you will think it unnecessary to give a step-by-step. After all, most rebuild kits only include a handful of parts and the location and function of most pieces are obvious. But there are some important additional steps that one can take to truly ensure the rebuild process goes smooth and that you won't have to do this over again immediately after reinstalling the carbs.
Here it goes!
First, I would like to outline the fact that not all Webers are the same. Not only are there different models of IDFs (the 36, the 40, the 44 and the much rarer 48), but there are "early" style carbs and "later" ones. I'll try to list some of the most obvious differences, which are to the best of my knowledge true in most cases, but may not hold true in all of them.
Here are the tools you'll need for the job:
-Carburetor rebuild kits (CB Performance or Redline are the most common)
-8mm open/closed end wrench
-10mm open/closed end wrench
-11mm open/closed end wrench
-19mm open/closed end wrench
-Smaller flat tip screwdriver
-Large flat tip screwdriver
-Brass brush
-Paint gun brush cleaning set
-Small hammer
-Brass punch set
-Razor blade
-Carb cleaner
-B-12 Carb dip
-Anti-seize
-Shop towels
-Compressed air source (preferably)
-Clean workspace, preferably with white background
Optional:
- (4) 3/8 x 24 Brass Hex grub/set screws
- Allen keys
-SAE Tap and Die set
Below is a picture of an early and late set of Weber 40 IDFs.
Click to view attachment
Some of the characteristics of EARLY versions are:
-Short emulsion tube holders
-Short throttle shafts with little overhang outside of the carb body
-Non-sealed, ball-in-cage style throttle shaft bearings
-Cam-actuated, non-adjustable accelerator pump assembly
-No ports for "ported" vacuum (still has 2 "manifold" vacuum ports)
-76 degree bevel throttle plates (this may or may not hold true for every set of early carbs)
-No throttle return springs installed from factory (thanks Kevin for clarification)
-Most (all?) were made in Italy and are stamped as such
Later style Weber 40 IDFs (Weber 40 XEs) are usually characterized by:
-Taller emulsion tube holders which extend above the carb top
-Longer throttle shafts
-Sealed black throttle shaft bearings
-Adjustable, spring cushioned accelerator pump assembly
-One pre-drilled ported vacuum port in addition to two threaded manifold vacuum ports
-78 degree bevel throttle plates
-Factory installed throttle return springs
-Made in Spain, but potentially also Italy and Brazil
Please note that most of these instructions to follow are also true for 44s and 48s as well. The main difference being the way that the secondary venturis are designed.
Full Version: So you want to rebuild your Webers?
This is Randy's set of later style, Spanish-made Webers as I received them.
Note the adjustable accelerator pump, tall emulsion tube holders, vacuum advance ports, etc.
The rust in the accelerator pump housing as well as on the other areas is due to water which is absorbed by the fuel. Even carbs that are not left outside will exibit signs of rusting and oxidation as the fuel sits and picks up more and more water, unless they are drained first. No big deal though, Randy
Note the adjustable accelerator pump, tall emulsion tube holders, vacuum advance ports, etc.
The rust in the accelerator pump housing as well as on the other areas is due to water which is absorbed by the fuel. Even carbs that are not left outside will exibit signs of rusting and oxidation as the fuel sits and picks up more and more water, unless they are drained first. No big deal though, Randy
Here are the throttle plates from underneath. Note the oxidation on the aluminum and the general crud on the carbs. There are several ways to clean up a set of Webers, and I'll show you how I did it without fancy equipment.
The best way is probably to use an ultrasonic cleaner, which will not only clean the corrosion on the outer portions of the carbs and throttle bodies, but will also remove scale and corrosion inside all of the small passageways. Unfortunately many of us don't have access to such a machine (although it's in my plans). Therefore, I decided to go a little different route with Randy's carbs. Below is another shot showing the deposits and oxidation in the fuel bowls.
Click to view attachment
.... And all of the stuff that fell out when they were turned upside down. Now aren't you glad you're rebuilding your carbs?
Click to view attachment
First, strip the carbs of all removable parts, keeping everything in baggies as you go. It's not if lose you lose a part, it's when. And tracking down individual replacement parts for Webers is not only a pain, but it will quickly drive up the cost of your rebuild and keep you off of the road longer.
Click to view attachment
**However, DO NOT, unless you deem it absolutely necessary, remove the throttle plates or shafts. Bob Tomlinson, in his Weber Tech Manual, specifically recommends avoiding removing these parts from the carbs because realigning the plates and shafts exactly as they were pre-rebuild is nearly impossible. Not to mention the process of driving out the old shaft(s) will likely render them bent, giving you a whole other set of variables to deal with (ask me how I know). In some cases, where the throttle shafts and/or bearings are seized in the bores, you will have no recourse but to remove them. In this case, make every attempt to mark and maintain each butterfly with its parent throttle body as, like most parts that wear, each fits in it's position in a unique way over time. **
Ideally, the next step would be to dip the carbs in cleaner to begin braking up all of the gunk that has built up on them over time. However, there is a reason why that may not be the best idea. Remember those throttle shaft bearings I spoke about - the sealed ones? Well, they're not perfectly sealed. And if you submerge them in something like B-12 Chemtool, you're liable to dry out and destroy those bearings, meaning you'll end up having to pull those throttle shafts afterall. Instead, what I did was to clean the outside of the carb with a good dousing of carb and/or brake cleaner, being careful to avoid the shaft bushings. Baste or pipette B-12 or other good carb cleaner into the fuel bowls and let that soak for 2-4 hours. As you can see below, if you are careful and keep the throttle plates closed, you can even soak the top of the butterflies if they seal well enough. Soak all of the parts you removed in B-12 at this time too. I like B-12 because it seems to do a better job breaking down hard deposits than the stuff you get in the can.
Click to view attachment
Click to view attachment
.... And all of the stuff that fell out when they were turned upside down. Now aren't you glad you're rebuilding your carbs?
Click to view attachment
First, strip the carbs of all removable parts, keeping everything in baggies as you go. It's not if lose you lose a part, it's when. And tracking down individual replacement parts for Webers is not only a pain, but it will quickly drive up the cost of your rebuild and keep you off of the road longer.
Click to view attachment
**However, DO NOT, unless you deem it absolutely necessary, remove the throttle plates or shafts. Bob Tomlinson, in his Weber Tech Manual, specifically recommends avoiding removing these parts from the carbs because realigning the plates and shafts exactly as they were pre-rebuild is nearly impossible. Not to mention the process of driving out the old shaft(s) will likely render them bent, giving you a whole other set of variables to deal with (ask me how I know). In some cases, where the throttle shafts and/or bearings are seized in the bores, you will have no recourse but to remove them. In this case, make every attempt to mark and maintain each butterfly with its parent throttle body as, like most parts that wear, each fits in it's position in a unique way over time. **
Ideally, the next step would be to dip the carbs in cleaner to begin braking up all of the gunk that has built up on them over time. However, there is a reason why that may not be the best idea. Remember those throttle shaft bearings I spoke about - the sealed ones? Well, they're not perfectly sealed. And if you submerge them in something like B-12 Chemtool, you're liable to dry out and destroy those bearings, meaning you'll end up having to pull those throttle shafts afterall. Instead, what I did was to clean the outside of the carb with a good dousing of carb and/or brake cleaner, being careful to avoid the shaft bushings. Baste or pipette B-12 or other good carb cleaner into the fuel bowls and let that soak for 2-4 hours. As you can see below, if you are careful and keep the throttle plates closed, you can even soak the top of the butterflies if they seal well enough. Soak all of the parts you removed in B-12 at this time too. I like B-12 because it seems to do a better job breaking down hard deposits than the stuff you get in the can.
Click to view attachment
Don't forget to remove these plates that cover the enrichment circuit. Might as well clean these out too, even though they *should* be inoperative. If you're careful you can probably reuse the gasket, if your carbs have them. The rebuild kits do not usually come with them.Click to view attachment
The enrichment circuits have a washer, plunger, spring and valve. You should clean out this area as well as added insurance. Plus this give you a chance to inspect the springs which push the enrichment valves down into their default position. If water has pooled in these areas, it is entirely possible the springs have rusted (like one of them on this carb) and collapsed. If they collapse, you need a replacement so that the valves stay down and don't leak fuel, causing an over-rich condition. While pushing a little downward tension on the little plunger to keep things from shooting across the room, simply pry up the little split washer. Then you'll be able to remove the spring and valve.
Click to view attachment
The enrichment circuits have a washer, plunger, spring and valve. You should clean out this area as well as added insurance. Plus this give you a chance to inspect the springs which push the enrichment valves down into their default position. If water has pooled in these areas, it is entirely possible the springs have rusted (like one of them on this carb) and collapsed. If they collapse, you need a replacement so that the valves stay down and don't leak fuel, causing an over-rich condition. While pushing a little downward tension on the little plunger to keep things from shooting across the room, simply pry up the little split washer. Then you'll be able to remove the spring and valve.
Click to view attachment
I no longer have Webers on my car but I thoroughly enjoyed your work so far. Looking for more as you progress.
good thread. well written and ++ for the pictures. nice job george. you may be able to source a sonic cleaner from a jewelry supply co.
k
k
Nice work George ... now finish them 
I did a similar write up on rebuilding Zenith 40 TIN carbs back in 2000.
If anyone's interested Click Here
Click to view attachment
I did a similar write up on rebuilding Zenith 40 TIN carbs back in 2000.
If anyone's interested Click Here
Click to view attachment
I like the closeup pictures.
Nice work!
John
QUOTE(ThePaintedMan @ Apr 8 2013, 11:21 PM) 
The enrichment circuits have a washer, plunger, spring and valve. You should clean out this area as well as added insurance. Plus this give you a chance to inspect the springs which push the enrichment valves down into their default position. If water has pooled in these areas, it is entirely possible the springs have rusted (like one of them on this carb) and collapsed. If they collapse, you need a replacement so that the valves stay down and don't leak fuel, causing an over-rich condition. While pushing a little downward tension on the little plunger to keep things from shooting across the room, simply pry up the little split washer. Then you'll be able to remove the spring and valve.
Click to view attachment
In the past I've drilled and tapped these for a small brass hex head plug and a small rod and I permanently disabled this circuit.
Thanks guys,
The carbs are actually much further along, but I suck at uploading pictures. This thread will be a long work in progress, including jetting as I understand it.
Mark, that Zenith looks killer!
Other Mark (Henry), I've seen that trick as well, but since they aren't my carbs, and I don't know if Randy will ever want to resell them later, I'm hesitant to tap anything. But you're right, it's one way to make sure they never leak. It's a pretty ingenious little setup from the diagrams I've seen though - sort of like a choke, but just adds extra fuel instead of cutting air.
The carbs are actually much further along, but I suck at uploading pictures. This thread will be a long work in progress, including jetting as I understand it.
Mark, that Zenith looks killer!
Other Mark (Henry), I've seen that trick as well, but since they aren't my carbs, and I don't know if Randy will ever want to resell them later, I'm hesitant to tap anything. But you're right, it's one way to make sure they never leak. It's a pretty ingenious little setup from the diagrams I've seen though - sort of like a choke, but just adds extra fuel instead of cutting air.
QUOTE(ThePaintedMan @ Apr 10 2013, 09:13 AM)
Thanks guys,
The carbs are actually much further along, but I suck at uploading pictures. This thread will be a long work in progress, including jetting as I understand it.
Mark, that Zenith looks killer!
Other Mark (Henry), I've seen that trick as well, but since they aren't my carbs, and I don't know if Randy will ever want to resell them later, I'm hesitant to tap anything. But you're right, it's one way to make sure they never leak. It's a pretty ingenious little setup from the diagrams I've seen though - sort of like a choke, but just adds extra fuel instead of cutting air.
Personally the circuit sucks big time, if they ever get stuck open they will wash down the cylinders. All Gene Berg carbs sets were done this way.
QUOTE(Mark Henry @ Apr 10 2013, 10:10 AM)
Personally the circuit sucks big time, if they ever get stuck open they will wash down the cylinders. All Gene Berg carbs sets were done this way.
Good point. If Gene did it, then it's good enough for me. I'll ask Randy what he thinks. Thanks for your input!
Okay! I'll stop lurking. George, I really appreciate your thoroughness with the rebuild. You are taking this much past my know-how, and it's exciting to imagine these whirling my next motor along.
I'm absolutely fine with the mod as discussed above. It wasn't with this set of Webers, but rather on my first set back in the late 90s that had this circuit jam up from time to time. I'm lucky I didn't bend a rod, as I'd come out to the car and twice had it where it would have a cylinder that was full of fuel. Funny how gasoline doesn't compress like air, huh?
Thanks again!
I'm absolutely fine with the mod as discussed above. It wasn't with this set of Webers, but rather on my first set back in the late 90s that had this circuit jam up from time to time. I'm lucky I didn't bend a rod, as I'd come out to the car and twice had it where it would have a cylinder that was full of fuel. Funny how gasoline doesn't compress like air, huh?
Thanks again!
Just be careful tapping that you don't put too much pressure on the casting or it will break.
Drill to the correct size, use a sharp tap and clean it often. It should be cutting as smooth as butter.
Use a brass hex grub screw, if you need a rod make sure it is also brass.
I'd avoid a NPT tap and plug, if you do use one be damn careful not to put it in tight. Use a drop of locktite if you like, no teflon!
Drill to the correct size, use a sharp tap and clean it often. It should be cutting as smooth as butter.
Use a brass hex grub screw, if you need a rod make sure it is also brass.
I'd avoid a NPT tap and plug, if you do use one be damn careful not to put it in tight. Use a drop of locktite if you like, no teflon!
You can pick up a cheap sonic cleaners at Harbour Frieght or Northen Tool.
Finishing up where I left off...
Once you have removed the lock washer clip at the top of the enrichment circuit, you can begin to pry up on the enrichment piston bodies. A small screwdriver will suffice, but be careful. Using the body of the carb as a lever is risky and it's easy to break the casting. If it's stuck in there (and it likely will be), you can try to soak the circuit in PB Blaster. If that does not work, a VERY small amount of localized heat may help free up the gummy gasoline that is gluing the piston in it's bore. Of course, be very careful to make sure that any remaining flammable liquids are gone first.
Once removed, clean the pistons and their seats as best as possible.
Once you have removed the lock washer clip at the top of the enrichment circuit, you can begin to pry up on the enrichment piston bodies. A small screwdriver will suffice, but be careful. Using the body of the carb as a lever is risky and it's easy to break the casting. If it's stuck in there (and it likely will be), you can try to soak the circuit in PB Blaster. If that does not work, a VERY small amount of localized heat may help free up the gummy gasoline that is gluing the piston in it's bore. Of course, be very careful to make sure that any remaining flammable liquids are gone first.
Once removed, clean the pistons and their seats as best as possible.
Now you're ready to start tapping. First, plug the bottom of the enrichment orifice to prevent aluminum shavings from falling in. A small piece of paper towel soaked in gear oil works well. This was an old carb body that was cracked, so it is not pictured here.
If available, use a 21/64 drill bit to make it easier for the tap to do it's job. Drill down approximately 3/8 of an inch into the bore. Blow out the bore to remove shavings.
Then, use a sharp 3/8 x 24 fine thread tap, threading approximately 3/8 inch into the bore. A metric tap might work as well, but since these will never need to be removed, I used what was readily available. Go slow and use plenty of cutting oil or gear oil as a substitute. You may wish to stop halfway through to blow out the tap and bore again.
If available, use a 21/64 drill bit to make it easier for the tap to do it's job. Drill down approximately 3/8 of an inch into the bore. Blow out the bore to remove shavings.
Then, use a sharp 3/8 x 24 fine thread tap, threading approximately 3/8 inch into the bore. A metric tap might work as well, but since these will never need to be removed, I used what was readily available. Go slow and use plenty of cutting oil or gear oil as a substitute. You may wish to stop halfway through to blow out the tap and bore again.
Once both sides are done, remove your packing material from the bore and reinstall the piston. Give it a few light taps to ensure it's seating fully.
Then, install a 3/8 x 24 fine thread grub/set screw. Brass is preferred (thanks Mark Henry) but since these will likely never be removed, steel is also acceptable. Just don't put too much pressure on them.
The set screws should sit below the top of the carb body when properly installed.
Then, install a 3/8 x 24 fine thread grub/set screw. Brass is preferred (thanks Mark Henry) but since these will likely never be removed, steel is also acceptable. Just don't put too much pressure on them.
The set screws should sit below the top of the carb body when properly installed.
Finally, you should be ready for reassembly. Blow out the carb bodies and bowls well before you start.
First, give the primary venturis/chokes a quick, light sanding on their outer face to remove any gum deposits. Clean them with solvent and install into their respective bores. The numbers should face up.
Click to view attachment
Install the choke hold down screws on the outside of the carb body with their associated nuts. The venturi will have a small dimple in it which should line up with the screw.
Click to view attachment
Then install the secondary venturies with the "fat" end of the aerofoil facing up. One side of the venturi will have a retaining spring which should line up with it's small slot in the carb body.
Click to view attachment
NOTE: If you have the time, you can use a jewelers file and some sandpaper to smooth out any casting imperfections on both the primary and secondary venturis. For most people's uses this will prove unnecessary, but for the racers, every little bit counts. You can see some of the casting remnants below.
Click to view attachment
First, give the primary venturis/chokes a quick, light sanding on their outer face to remove any gum deposits. Clean them with solvent and install into their respective bores. The numbers should face up.
Click to view attachment
Install the choke hold down screws on the outside of the carb body with their associated nuts. The venturi will have a small dimple in it which should line up with the screw.
Click to view attachment
Then install the secondary venturies with the "fat" end of the aerofoil facing up. One side of the venturi will have a retaining spring which should line up with it's small slot in the carb body.
Click to view attachment
NOTE: If you have the time, you can use a jewelers file and some sandpaper to smooth out any casting imperfections on both the primary and secondary venturis. For most people's uses this will prove unnecessary, but for the racers, every little bit counts. You can see some of the casting remnants below.
Click to view attachment
Next, move on to installing the accelerator pump jets. If you have a jet gauge (and I highly recommend you do), gently push it into the nozzle to remove any final remnants of gum or other material that may be stuck here. If you do not, and end up having a plugged pump jet after installation, you'll be forced to pull the top of the carburetor off again to clean them. As tempting as it might be, do not use a staple or other object, as the jet orifices are very small and you risk reaming them out to some unknown size.
Place one of the copper/brass sealing rings on the pump hold down screw, then the jet, then one more sealing ring. They should sandwich the jet from top and bottom. Tighten the screw down firmly but without excessive force using a wide-blade flathead screwdriver.
Place one of the copper/brass sealing rings on the pump hold down screw, then the jet, then one more sealing ring. They should sandwich the jet from top and bottom. Tighten the screw down firmly but without excessive force using a wide-blade flathead screwdriver.
Next, begin installing the remaining hardware on the outside of the carb body. This includes the air bypass screws, idle mixture screws, vacuum port plugs (if equipped), and the idle speed screws. I recommend using a very small amount of anti-seize on them as it will make it much easier to make adjustments by hand when tuning later on. You also may wish to clean up any gum deposits on the faces of the needles with fine grit sandpaper. As mentioned by rhodyguy, don't forget the small o-rings that go under the caps for the idle mixture screws, and make darn sure you don't lose them! Also, be sure to install them on your idle jet holders as well.
Click to view attachment
Here is how the final setup should look.
Click to view attachment
Also, note the difference in size between the idle mixture screw springs and the idle return springs. The return spring is a little beefier.
Click to view attachment
Here is how the final setup should look.
Click to view attachment
Also, note the difference in size between the idle mixture screw springs and the idle return springs. The return spring is a little beefier.
Now move on to the accelerator pump cover.
Note that there are two style of pump covers and associated diaphragms. If your carbs have and adjustable pump lever rod (pictured here) then you will use the diaphragm in the kit that only has a metal face. The one with the white button on top is used with earlier style carbs with a non-adjustable lever rod.
Click to view attachment
First place the diaphragm on the pump cover. I like to thread the screws through the holes in the diaphragm first to locate it correctly and prevent the rubber from being pinched or the seal leaking upon installation.
Click to view attachment
Finally, place the spring on the recess in the body and install the cover. Do not overtighten the screws.
Note that there are two style of pump covers and associated diaphragms. If your carbs have and adjustable pump lever rod (pictured here) then you will use the diaphragm in the kit that only has a metal face. The one with the white button on top is used with earlier style carbs with a non-adjustable lever rod.
Click to view attachment
First place the diaphragm on the pump cover. I like to thread the screws through the holes in the diaphragm first to locate it correctly and prevent the rubber from being pinched or the seal leaking upon installation.
Click to view attachment
Finally, place the spring on the recess in the body and install the cover. Do not overtighten the screws.
Great work George! This may be a candidate for the Classics forum.
Next, move on to the top of the carb. Remove the 19mm brass nut at the fuel line neck, which holds the mesh fuel filter. Clean out the filter and passageway thoroughly and reinstall the filter as well as the new red/orange gasket supplied in the kit. Don't overtighten this fitting, or you'll crush the gasket and ruin it. (Eventually I'd like to find a suitable aluminum style sealing ring to replace the cardboard ones.) You can add a small dab of grease to both sides of this washer to improve the seal and prevent tearing.
If you have not already done so, drive out the float arm pin and remove the float. Be sure to do this with an appropriately sized punch and hammer and with the carb top well supported and far away from a position where it could fall on the ground. If it does, you're likely to ruin the carb top and finding a replacement in good condition is very difficult. I prefer to drive the pin out in the direction outlined below. Sometimes the pin can have a knurled end to it and if that end is forced through the non-slotted end of the float pin tower, it may break.
Once the pin is removed, remove the float and needle valve assembly.
Click to view attachment
Install the new top gasket (after scraping any residual gasket material off of course) and the needle valve base. Note that there is a small aluminum washer underneath this base that should be replaced with the one in your kit. Also, ensure that the two holes for the idle circuit vents exist on your gasket and will not block the idle circuit vents on the top of the carb bodies. I like to open these holes up a little with a flathead screwdriver just in case.
Click to view attachment
Clean the float of any debris and install the needle valve on the small tab at it's fulcrum. Install both into position and slide the pin back into position. Several taps of the hammer should be able to get it back into position. Again, note the knurled end of the pin and install it so the smooth end goes into the non-slotted holder first.
If you have not already done so, drive out the float arm pin and remove the float. Be sure to do this with an appropriately sized punch and hammer and with the carb top well supported and far away from a position where it could fall on the ground. If it does, you're likely to ruin the carb top and finding a replacement in good condition is very difficult. I prefer to drive the pin out in the direction outlined below. Sometimes the pin can have a knurled end to it and if that end is forced through the non-slotted end of the float pin tower, it may break.
Once the pin is removed, remove the float and needle valve assembly.
Click to view attachment
Install the new top gasket (after scraping any residual gasket material off of course) and the needle valve base. Note that there is a small aluminum washer underneath this base that should be replaced with the one in your kit. Also, ensure that the two holes for the idle circuit vents exist on your gasket and will not block the idle circuit vents on the top of the carb bodies. I like to open these holes up a little with a flathead screwdriver just in case.
Click to view attachment
Clean the float of any debris and install the needle valve on the small tab at it's fulcrum. Install both into position and slide the pin back into position. Several taps of the hammer should be able to get it back into position. Again, note the knurled end of the pin and install it so the smooth end goes into the non-slotted holder first.
Now comes the art of setting the float level. Though the methodology is the same, there are varying opinions on what the float level should be on Webers. CB Performance lists a 14 mm gap from the gasket to the very edge of the float, but does not specify a bottom float distance. The Weber Haynes manual and other sources list a 10mm gap and a full-open gap of 32mm, which is what I use. Racers may modify the float level depending on cornering loads and other factors, but the 10/32 measurements work for me.
First, turn the carb top over so that the float is toward the ceiling. Allow the float to rest on the needle valve and do not place any pressure on it. Using a steel ruler or caliper, measure the distance from the gasket to the edge of the float. If it is not 10mm, you will need to bend the small tab that the needle valve is retained on up or down to achieve the proper distance. Don't get frustrated as it may take you several tries to get it right.
Click to view attachment
First, turn the carb top over so that the float is toward the ceiling. Allow the float to rest on the needle valve and do not place any pressure on it. Using a steel ruler or caliper, measure the distance from the gasket to the edge of the float. If it is not 10mm, you will need to bend the small tab that the needle valve is retained on up or down to achieve the proper distance. Don't get frustrated as it may take you several tries to get it right.
Click to view attachment
nice write up george. don't forget to mention the little o-rings for the idle air mixture screws.
Next, turn the carb top over and allow the float to hang down freely. With the same procedure as before, measure the distance from the gasket to the same edge of the float as in the previous setting. Bend the tab at the back of the float fulcrum point as necessary to achieve the proper distance.
Click to view attachment
Once you're happy with the float settings, set the carb top down carefully and move back to the body. Give it one last look through, maybe a shot of carb cleaner in the bowl, and then blow it out upside down with compressed air. This is the last time you'll have to remove debris from it so be thorough. Once complete, install the top on the carb body and tighten down the five screws in a criss-cross pattern. I start with the centermost screw and work across towards the outside of the carb.
Click to view attachment
Once you're happy with the float settings, set the carb top down carefully and move back to the body. Give it one last look through, maybe a shot of carb cleaner in the bowl, and then blow it out upside down with compressed air. This is the last time you'll have to remove debris from it so be thorough. Once complete, install the top on the carb body and tighten down the five screws in a criss-cross pattern. I start with the centermost screw and work across towards the outside of the carb.
Now we need to install the linkage arms and associated hardware. Keep in mind that if you're not rebuilding the carbs that were on your car and you don't know what linkage was used previously, that the arms and spacers that you see may or may not be necessary for your setup. If you have questions, I am familiar with a few different types of linkage, so I might be able to help you determine if you have everything you need, or point you in the right direction of where to order it.
That being said, the general order should look like this. First is the round brass "Cymbal" sealing plate that keeps debris out of the bearing. On early carbs, this was essential since the bearings were not sealed, but they are still present on the later models with sealed bearings. Next is the very, very thin sealing washer seen below.
Click to view attachment
Now add the throttle return spring, if so equipped. There should only be one per carb, and the early Webers did not have them at all. Next is the appropriate throttle linkage arm or spacer, again, depending on which side of the carb you're working on.
Click to view attachment
Next install the locking tab washer and 11 mm thin nut. Do NOT forget to put some antiseize on the threads of the throttle shaft. When the nut rusts itself onto the shaft, it is notorious for taking threads with it, which will render the throttle shaft unusable and then you'll have to source a new throttle shaft, not to mention disassembling the entire carb again.
Click to view attachment
That being said, the general order should look like this. First is the round brass "Cymbal" sealing plate that keeps debris out of the bearing. On early carbs, this was essential since the bearings were not sealed, but they are still present on the later models with sealed bearings. Next is the very, very thin sealing washer seen below.
Click to view attachment
Now add the throttle return spring, if so equipped. There should only be one per carb, and the early Webers did not have them at all. Next is the appropriate throttle linkage arm or spacer, again, depending on which side of the carb you're working on.
Click to view attachment
Next install the locking tab washer and 11 mm thin nut. Do NOT forget to put some antiseize on the threads of the throttle shaft. When the nut rusts itself onto the shaft, it is notorious for taking threads with it, which will render the throttle shaft unusable and then you'll have to source a new throttle shaft, not to mention disassembling the entire carb again.
Click to view attachment
Just about done. Here is a housekeeping trick that I learned. The casting and drilling/manufacturing process of Webers means that a number of lead plugs are used to seal off several circuits of the carb. Often these plugs will leak or weep even minute amounts of gas over time. While it would be nice to replace all of these lead plugs, I don't feel that it's necessary. Instead, I take the time to use a small punch and peen these plugs in, hopefully mushrooming them out a little bit to prevent leaks. It's much easier to do this while they're out of the car rather than bending over and trying to stop them from leaking after you've got it all together.
Click to view attachment
Now is a good time to reassemble the main jet stacks as well. Pretty simple, but each component must be there to serve it's function. Below is a picture of the stack, with main jet, emulsion tube, air correction jet and main jet holder. These are later style main jet holders which "snorkel" above the top of the carb body, in comparison to the lower, early jet holders. Note: if you want to see a cool trick, check out Van Svenson's video on Youtube where he explains how to ensure that the main jets are seating properly. Once they're complete, go ahead and install them.
Click to view attachment
Finally, if you have an earlier style IDF without the adjustable accelerator pump rod, be sure to throw a little grease on the cam and the roller that actuates the accelerator pump rod.
Click to view attachment
Now is a good time to reassemble the main jet stacks as well. Pretty simple, but each component must be there to serve it's function. Below is a picture of the stack, with main jet, emulsion tube, air correction jet and main jet holder. These are later style main jet holders which "snorkel" above the top of the carb body, in comparison to the lower, early jet holders. Note: if you want to see a cool trick, check out Van Svenson's video on Youtube where he explains how to ensure that the main jets are seating properly. Once they're complete, go ahead and install them.
Click to view attachment
Finally, if you have an earlier style IDF without the adjustable accelerator pump rod, be sure to throw a little grease on the cam and the roller that actuates the accelerator pump rod.
+1 on making this a classic thread
That just about does it! You should have a nice and clean, fully functioning set of Webers now. I like to hit them with a few light coats of this stuff, CRC 3-36. It works great on protecting aluminum, but it can be difficult to find. You can also use lanolin spray, and either product should ideally be sprayed on the carbs from time to time if possible.
Here's how Randy's carbs turned out:
Here's how Randy's carbs turned out:
QUOTE(ThePaintedMan @ Dec 17 2013, 04:57 PM)
Just about done. Here is a housekeeping trick that I learned. The casting and drilling/manufacturing process of Webers means that a number of lead plugs are used to seal off several circuits of the carb. Often these plugs will leak or weep even minute amounts of gas over time. While it would be nice to replace all of these lead plugs, I don't feel that it's necessary. Instead, I take the time to use a small punch and peen these plugs in, hopefully mushrooming them out a little bit to prevent leaks. It's much easier to do this while they're out of the car rather than bending over and trying to stop them from leaking after you've got it all together.
Click to view attachment
Now is a good time to reassemble the main jet stacks as well. Pretty simple, but each component must be there to serve it's function. Below is a picture of the stack, with main jet, emulsion tube, air correction jet and main jet holder. These are later style main jet holders which "snorkel" above the top of the carb body, in comparison to the lower, early jet holders. Note: if you want to see a cool trick, check out Van Svenson's video on Youtube where he explains how to ensure that the main jets are seating properly. Once they're complete, go ahead and install them.
Click to view attachment
I had one of these plugs completely shoot out during a DE event at Watkins Glenn many years ago, which caused a 1/4" stream of fuel to pour out of the carb across a hot engine. Got Very Lucky that day. Since then I have covered the lead plugs with a two part epoxy. Great write up!
QUOTE(nolift914 @ Dec 17 2013, 07:21 PM)
[I had one of these plugs completely shoot out during a DE event at Watkins Glenn many years ago, which caused a 1/4" stream of fuel to pour out of the carb across a hot engine. Got Very Lucky that day. Since then I have covered the lead plugs with a two part epoxy. Great write up!
That's a great idea! I don't think Randy will have that problem, but it's something I'll definitely consider for my car.
Just wanted to thank Randy and McMark for giving me the opportunity to work on his carbs. Mark could have done them, but I needed an excuse to do a writeup.
Also thanks to Tim, Kevin and everyone else for the kind words and vote of confidence. I know this is pretty much a no-brainer for some folks, but some people are pretty intimidated by carbs and there were some things that I've learned that I wanted to include so others don't have the same headaches I did when I first started rebuilding them.I'd like to do more of these in the future, and eventually a Dellorto writeup. I've got a set of 44s that I'm working on now which will go into the classifieds when I get them done. Going to use some of that money towards a good parts washer and the rest towards Chumpcar endeavors.
If there's anything else you guys can think of that I missed, feel free to chime in.
Nice job. I just read through your thread.
The part about setting the float levels, I have found to be the trickiest. I have heard that unless they are exactly the same side to side they will leak through the needle valves. The critical position is when it closes. I have found it works better to use an allen key between the float and carb top than to use calipers. The other tip which I offer is to blow (with your mouth, yes) through them to make sure they are closed there. Say if they should be closed at 10mm from the top, stick an 11mm allen key between and ensure that they open, 10mm and make sure they close.
Another thing to check is to weigh the floats. Dell floats say right on them what they should weigh, but a bad float will weigh a lot more (hard to tell without a scale though). With a heavy float and all else being right, the carb will still drip and fill the cylinders with fuel.
The part about setting the float levels, I have found to be the trickiest. I have heard that unless they are exactly the same side to side they will leak through the needle valves. The critical position is when it closes. I have found it works better to use an allen key between the float and carb top than to use calipers. The other tip which I offer is to blow (with your mouth, yes) through them to make sure they are closed there. Say if they should be closed at 10mm from the top, stick an 11mm allen key between and ensure that they open, 10mm and make sure they close.
Another thing to check is to weigh the floats. Dell floats say right on them what they should weigh, but a bad float will weigh a lot more (hard to tell without a scale though). With a heavy float and all else being right, the carb will still drip and fill the cylinders with fuel.
lost one of those plugs once while driving. engine compartment was covered in fuel. collected what i could out of the car and waited for the car to burst into flames. it didn't. found the plug on the engine shelve, hammered it in with a rock, drove the short distance home, pulled the carbs, made sure the plugs were all fully seated, degrease and epoxyed them. i wasn't driving on a freeway at the time. if i had been i'm sure it would have been a dif story.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.