Author Topic: Weber carb set-up (Read 151842 times)

BPellerine · « **Reply #450 on:** January 27, 2014, 06:20:59 PM »

if he is using a stock frame closer together is better for jet removal I have to put a frame kit in with my setup to get the mains out.they will not clear the frame.bill

Tintop · « **Reply #451 on:** January 27, 2014, 06:21:45 PM »

slikwilli420....the universal kit just links the carbs together so they can be sync'd to open together. No provision for cable / linkage attachment. What was your plan there?? Opening dual carbs from only one end will eventually lead to a bent throttle shaft. The RC setup is designed without any linkage between the carbs (tight spacing). It uses either two cables (one at each end), or a rod-end supported shaft with seperate levers & links to each carb, and a 3rd lever for cable attach. If your going to link them (wider spacing) then the PM3719 kit would be a better choice (single center pull, cable).

Tintop · « **Reply #452 on:** January 27, 2014, 06:32:21 PM »

Not the best pic but this is the dual setup on my '7'. The green cable is the throttle which goes to a lever beside the rear carb. It's attached to a rod mounted to the manifold in rod ends. In the center is an adjustable link that attaches to the Weber carb link.

slikwilli420 · « **Reply #453 on:** January 27, 2014, 06:51:59 PM »

Tintop, Im using the Pierce universal kit with this part number PM3702-L. I will drill the manifold for the rod ends and have them positioned as close to the throttle arm as possible. This should eliminate any chance of bending. For the wider manifold, I will have the linkage on either the right or left side of each manifold and the lever for the throttle cable in the center, with an additional return spring. On the RC design, linkage will be on the outsides with a rod end near each throttle arm, with another at the arm that goes to the throttle cable. This should make for a strong setup with no twisting or risk of throttle shaft damage.

As to access, I have added a frame splice kit made from four joints used for offroad trucks and race cars. I will be cross documenting the Weber build here and in my build thread here:

http://forums.sohc4.net/index.php?topic=133638.0

754 · « **Reply #454 on:** January 27, 2014, 09:43:56 PM »

I think its getting confusing here.
For years I ran a splayed MPD manfold.. No issue accessing jets.

The info I posted today was to aid in determing center distances of the carbs before water jetting some carb mounting plates that are partly based on the RC manifold.
And then I said.. Anyone running the RC tell us how. Jet access is on a stock frame..I myself have not yet tried the pictured manifold.
The centre ports spacing on the RC is 73 mm.

I do not believe actuating the throttle shaft from one end only , could possibly twist anything, its a very light pressure appplied...

scottly · « **Reply #455 on:** January 27, 2014, 10:48:10 PM »

With an MPD splayed manifold and the Seeley frame, I can't remove the mains/emulsion tubes without leaning the carbs back so far that they pull off the spigots. (hey Frank, where are my new silicone carb boots??

)

754 · « **Reply #456 on:** January 27, 2014, 10:49:33 PM »

Check your pm..

slikwilli420 · « **Reply #457 on:** January 28, 2014, 12:55:01 PM »

Here is a rendering of the manifold plate I am having cut. The spigots will be in the RC style and will be lazer welded to the plate to complete the manifold. The top will be drilled for the supports for the throttle shaft. I will also add a fitting for an external return spring.

754 · « **Reply #458 on:** January 28, 2014, 02:19:04 PM »

The total length of the manifold is 21.925 spigot diameter is 1.525. Spacing of 1set or pair of spigots is 3.535
The thickness is approx 3/8 to 1/2 will check later.
How thick will yours be and will you sell just the plate?

BPellerine · « **Reply #459 on:** January 28, 2014, 03:23:04 PM »

saw a pic of a bike with a weber mounted and the guy made a disc much like the one on the handlebar end of throttle ass ,bolts to the outside of throttle shaft and small bracket on one of the airhorn bolts to hold cable could work when space is tight in the centre of carbs .I will try to get a pic.bill

krusty · « **Reply #460 on:** January 28, 2014, 03:36:48 PM »

FWIW There's a feature in a mag I found on fitting Weber carbs. 1973 issue of "Motorcycle Riders Guide for Honda Fours"
Also has an article on dual disc conversion.

754 · « **Reply #461 on:** January 28, 2014, 03:53:33 PM »

The disc thing you describe is used on keihins on Harleys. And on Weber kits for H-D..
And easy to make.. Except for the double D hole to the shaft..

slikwilli420 · « **Reply #462 on:** January 28, 2014, 04:09:59 PM »

My plate will be 1/2"aluminum with spigots as short as they can be for clearance to the rear. As to throttle cable mounting I have not gotten there yet. As to selling them if I could do a kit in the RC style where you could use stock insulators that would be great. I don't know about a price but once I have the spigot designed I could get quotes to have a bunch done on cnc.

Tintop · « **Reply #463 on:** January 28, 2014, 06:25:06 PM »

It would be a lot cheaper to have them waterjet cut. All you need is an AutoCad .dwg file, as anyone with a waterjet can use/convert from that. I used MasterCam (converted to AutoCad) to make the Weber manifold for my sidecar XS application.

BPellerine · « **Reply #464 on:** January 28, 2014, 06:34:18 PM »

re post 461 yeah Frank I thought it would be easy to make and might be a solution for someone .bill

slikwilli420 · « **Reply #465 on:** January 28, 2014, 06:53:41 PM »

Tintop, the plate will be water jet cut but since the spigots have multiple dimensions both inside and out, the easiest way will be to use thick walled aluminum tubing. I will have access to a lathe later this week and will hopefully get my first set of four made up. Once the parts are done I will post pictures here.

Tintop · « **Reply #466 on:** January 28, 2014, 07:32:48 PM »

To allow for the mounted angle of the branches (spigots in your case) I made the holes at both ends slightly smaller than required. This allows for them to be port matched, and the angle blended in for smooth air flow. To compensate for the change it diamenter I had two dia of tubes (slip fit) welded together midway. Smaller went full distance but most was blended away at the larger end. You likely don't have to do as much, but you should allow for some material removal for blending.

754 · « **Reply #467 on:** January 28, 2014, 09:08:09 PM »

More info. The RC is only about .325thick ..EXCEPT on the corners wephere the throttle cables mount..there is a flat bar looking piece about .812 x .37x 1 inch long.. Think a tab weldedto the top outerside of the backing plate.
Now the ports are about 2 inch OD coming out of the flat plate area.then stepped where the stock rubber fastens.
Keep in mind the port centers of right or left side of motor vary a lot from the Weber spacing, so the. Transition must be hand ported or be mostly done in the pattern if casting.

FWIW i compared a KO backing plate against the RC spigot and there is a world of difference in the actual spacing.

Ricky_Racer · « **Reply #468 on:** February 02, 2014, 10:57:07 AM »

You've got a Lotus 7, Tintop? Dayum. Now I'm really envious!

What a great ride that'd be to have here in Sunny Socal! RR

Tintop · « **Reply #469 on:** February 02, 2014, 12:00:06 PM »

Actually had is the operative word RR, it's down in the US somewhere now. Engine was built from used left over parts from my (also now gone) Lotus Cortina Mk2 race car. Brian Hart dry sump'd, Cosworth rods & pistons, billet crank & main caps. I've also enjoyed an Elan (S2), and an Elan Plus2 'Big Valve' over the years.

Ricky_Racer · « **Reply #470 on:** February 02, 2014, 12:03:03 PM »

Tintop, you are definitely Da Man! Thanks for the reply. I wish I could afford the price a Caterham or Lotus 7 is going for these days! What a great fair-weather car! RR

slikwilli420 · « **Reply #471 on:** February 12, 2014, 07:56:02 AM »

I wanted to post a quick pic of the waterjet work that I had done to create my manifold plate. Now to get the spigots machined and welded on.

BPellerine · « **Reply #472 on:** February 12, 2014, 10:42:06 AM »

nice stuff .bill

bear · « **Reply #473 on:** February 17, 2014, 03:55:46 PM »

Quote from: scottly on January 27, 2014, 10:48:10 PM

(hey Frank, where are my new silicone carb boots?? )

Oooo.............where can those?
My last decent set gave up the gost @ PI

Cheers,
Brian

754 · « **Reply #474 on:** February 17, 2014, 10:03:27 PM »

If they are straight, i can cut some if you figure the length

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Author Topic: Weber carb set-up (Read 151842 times)