Topic: Weber Carbs fitment

[afkrejci90]

Got another set of reproduction boots in today, only using the #2 and #3 that was mentioned in the Weber mega thread.  Not a 100% perfect fit by any means but they will fit with some persuasion.  3D printed some plates and spigots for a mock up to find out the clearance in between the carburetors.  Not much clearance so I'll have to cut down the shafts.

[Don R]

 You didn't mess around, what's next, CNC, metal print or cast?  I do CAD myself, except cardboard aided design. 
   I ordered a pair of those banjo fittings, they are a lot cleaner looking than the multi piece ones I have now, and they aim towards where the fuel is.
   

[afkrejci90]

You didn't mess around, what's next, CNC, metal print or cast?  I do CAD myself, except cardboard aided design. 
   I ordered a pair of those banjo fittings, they are a lot cleaner looking than the multi piece ones I have now, and they aim towards where the fuel is.
 

I still need to make a mockup with the throttle system and nitrous foggers.  The plate will be CNC'd.  The spigots in their current configuration can easily be machined on a 3 axis CNC or lathe.  I'm going to mess around with the design of the outer ones to match up closer to where the boots are.  I will probably 3D print those out of a high temp filament which will help keep the weight down.

[MRieck]

You didn't mess around, what's next, CNC, metal print or cast?  I do CAD myself, except cardboard aided design. 
   I ordered a pair of those banjo fittings, they are a lot cleaner looking than the multi piece ones I have now, and they aim towards where the fuel is.
 

I still need to make a mockup with the throttle system and nitrous foggers.  The plate will be CNC'd.  The spigots in their current configuration can easily be machined on a 3 axis CNC or lathe.  I'm going to mess around with the design of the outer ones to match up closer to where the boots are.  I will probably 3D print those out of a high temp filament which will help keep the weight down.

Good for you for using a plate to install the foggers in. I installed several NOS set ups in the 90's and the instructions say to drill the insulator (boot). Don't ever do it. Plus...use Teflon paste.....do NOT use Teflon tape to seal those nozzles.

[MRieck]

 I told Frankie I would send him all my old NOS stuff and I was looking at it today....God days go by so fast especially when you're retired. It's coming sir.

[afkrejci90]

You didn't mess around, what's next, CNC, metal print or cast?  I do CAD myself, except cardboard aided design. 
   I ordered a pair of those banjo fittings, they are a lot cleaner looking than the multi piece ones I have now, and they aim towards where the fuel is.
 

I still need to make a mockup with the throttle system and nitrous foggers.  The plate will be CNC'd.  The spigots in their current configuration can easily be machined on a 3 axis CNC or lathe.  I'm going to mess around with the design of the outer ones to match up closer to where the boots are.  I will probably 3D print those out of a high temp filament which will help keep the weight down.

Good for you for using a plate to install the foggers in. I installed several NOS set ups in the 90's and the instructions say to drill the insulator (boot). Don't ever do it. Plus...use Teflon paste.....do NOT use Teflon tape to seal those nozzles.

That might work if you had and old crusty boot that had no more flex 

[bear]

Hey Brian, good to hear from you! How are you and your lovely lady doing?

I'm blowing a bit of black smoke mate, but overall not bad for an old fossil.
The lovely Evelyn is doing well, but she keeps slipping a link out my chain when I'm not looking. It's just about down to the choke collar and apparently I'm still not to be trusted.
Although it's been quite awhile since I've been threatened with a good stabbing, God luvá.
I will let her know you where asking after her.
How thing's going in your part of the word?     

[afkrejci90]

Made another mockup plate this time full size and now have the carbs assembled as a complete "rack".  Had to mess around with the design of some of the spigots and make two of them offset from center so that they would match up to the boots more precisely and not putting to much stress on the boots.

[scottly]

Hey Brian, good to hear from you! How are you and your lovely lady doing?

I'm blowing a bit of black smoke mate, but overall not bad for an old fossil.
The lovely Evelyn is doing well, but she keeps slipping a link out my chain when I'm not looking. It's just about down to the choke collar and apparently I'm still not to be trusted.
Although it's been quite awhile since I've been threatened with a good stabbing, God luvá.
I will let her know you where asking after her.
How thing's going in your part of the word?   

I'm blowing a bit of blue smoke myself these days, but I'm not sure if it's from worn piston rings or worn valve guides, not that it makes any difference at this stage.

[scottly]

Made another mockup plate this time full size and now have the carbs assembled as a complete "rack".  Had to mess around with the design of some of the spigots and make two of them offset from center so that they would match up to the boots more precisely and not putting to much stress on the boots.

Since you are still in the design phase, consider making the manifold two pieces, if for no other reason than to make installation easier. Mounting an RC setup is a #$%*, trying to shove all four boots on at the same time. It literally took Frank, Jerry, and I to do it when we all met up in Deloris, CO.    

[afkrejci90]

Made another mockup plate this time full size and now have the carbs assembled as a complete "rack".  Had to mess around with the design of some of the spigots and make two of them offset from center so that they would match up to the boots more precisely and not putting to much stress on the boots.

Since you are still in the design phase, consider making the manifold two pieces, if for no other reason than to make installation easier. Mounting an RC setup is a #$%*, trying to shove all four boots on at the same time. It literally took Frank, Jerry, and I to do it when we all met up in Deloris, CO.    

The final version will have the spigots bolted to the plate.  So each individual boot and spigot goes on and then the plate slips on and get bolted to the spigots.  There's studs on the backside of the plate for the carbs to mount to, they are in this version but you can't really see them.

[Don R]

 I'm wondering if there are significantly different jetting numbers between a healthy 836 like Scottly's and a 1,000cc motor like what they used on an RC Cobra?

[scottly]

The final version will have the spigots bolted to the plate.  So each individual boot and spigot goes on and then the plate slips on and get bolted to the spigots.

What does the other side of the spigots look like?

[scottly]

I'm wondering if there are significantly different jetting numbers between a healthy 836 like Scottly's and a 1,000cc motor like what they used on an RC Cobra?

All things being equal, a 1000cc motor is sucking as much air and fuel at 7500 RPM as an 836cc at 9000 RPM, and sucking even harder at higher RPMs. The main difference would be the size of the chokes: my 836 is happy with 30mm, but can't take full advantage of 32mm chokes, at least with a stock, un-ported K1 head. I did try 32s on the dyno, and had to increase the main jet to compensate.

[Don R]

I'm wondering if there are significantly different jetting numbers between a healthy 836 like Scottly's and a 1,000cc motor like what they used on an RC Cobra?

All things being equal, a 1000cc motor is sucking as much air and fuel at 7500 RPM as an 836cc at 9000 RPM, and sucking even harder at higher RPMs. The main difference would be the size of the chokes: my 836 is happy with 30mm, but can't take full advantage of 32mm chokes, at least with a stock, un-ported K1 head. I did try 32s on the dyno, and had to increase the main jet to compensate.

  Makes sense. I always think back to our Jr. Dragster motors, when we got the .563 stroker cranks, with the same engine, cam, porting, valves and some more compression our Mikuni could use a smaller main jet. They pulled more air and let the carb work like it wanted to.

[afkrejci90]

The final version will have the spigots bolted to the plate.  So each individual boot and spigot goes on and then the plate slips on and get bolted to the spigots.

What does the other side of the spigots look like?

Working on the final print but here are some renders of the finished product.

[scottly]

So there is no taper from the 40mm carb side down to the ID of the head spigots?

[afkrejci90]

Its hard to see but there is a taper from 40mm to the ID of the boots.

[Don R]

 Very nice, thanks for letting us see the process.

[afkrejci90]

Here's the final mockup with foggers installed.  I still need to find a throttle wheel but that will have to wait for the mockup on the bike so I can figure out the cable length.

[Don R]

 Here is the opportunity to make the throttle as quick or slow as you like.

[afkrejci90]

Here is the opportunity to make the throttle as quick or slow as you like.

I noticed that with the linkage arms, the attachment point could be closer to the rod to slow it down a bit.  They came with the kit so that's just what I used but I think I'll be making my own.

[Don R]

 This morning, I was assembling a 750 and decided to test fit my MPD manifold and Webers, I split the manifold and put on the right one. I suspected that the carb mount goes to the stock airbox mount, if I bend it horizontal at the bottom of the frame tube, that seems to be true.
 As Scott suggested, I see why the studs I bought won't be ideal because there's no room to remove the carbs over studs if the air cleaners are on.
 The pics give an idea of how much room there is to work with. That carb would be a half inch higher if the tab was bent. This bike is going back stock so I don't want to bend them.

[afkrejci90]

This morning, I was assembling a 750 and decided to test fit my MPD manifold and Webers, I split the manifold and put on the right one. I suspected that the carb mount goes to the stock airbox mount, if I bend it horizontal at the bottom of the frame tube, that seems to be true.
 As Scott suggested, I see why the studs I bought won't be ideal because there's no room to remove the carbs over studs if the air cleaners are on.
 The pics give an idea of how much room there is to work with. That carb would be a half inch higher if the tab was bent. This bike is going back stock so I don't want to bend them.

That's the other issue I'm going to run into, making them fit with some sort of air cleaner and finding an air cleaner if not outright making a custom one.

[Don R]

 I was surprised when the 90* fuel fitting was out from under the gas tank. I've seen some kipa air filters that appear to be pretty short. I'm hoping to get hose on 8mm barb on one end and 5.5mm on the petcock.