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MG MGB GT V8 Factory Originals Technical - SU carb linkage

Does anyone have any details on the carb linkage which enables 2 SU HIF6 carbs to be linked together as per the MGBV8 standard setup. I seem to be able to buy the manifold, plenum and carb parts but not the linkage.
Simon Forsdyke

Simon

I had to make my own linkage including the mechanism to balancing of the air flow.

I thought Clive Wheatley may be able to supply the linkage.

Does anyone know?
Ian Buckley

http://www2.et.byu.edu/~jmv/linkage.htm
Csar

Caesar

Unbelievable!

Can you tell us more?

Ian Buckley

good isn't it - the manual helps too - Simon, the anchor for the carb end of the cable is vital and may need to be made.
RMW

I'm hoping to cut a set out of flat stainless plate and bend, drill and tap the necessary holes. I have access to a wire EDM, this would be a piece of cake, I just have to write the program if I can find the orignal CAD files.
Jake

"anchor for the carb end of the cable ... may need to be made"

Which cable? My replacement choke cable came with the correct end.
Paul Hunt

Jake, would you be interested in selling me a set?
I hope to give Clive a call tomorrow. His colleage confirmed that they do not sell them separate from the carbs.
Do you have the dimensions of the linkages. I may be able to make myself if you have the drawings.
Simon Forsdyke

RMW

The manual helps too?

Ian Buckley

I will probably make a set and see if it fits my own setup and then we will see about making more.
Jake

I must admit to using a pair of left hand carbs (not a mirror match) and am going to use them conventionally except connect them together remotely via a pivoting bar. It means I can use my brand new set of carbs I picked up for 40. The proper pair I've got are pretty knackered and this way should allow better adjustment.
Stuart Robson

Ian - e-mail if you want a jpeg.
Paul - I think Jake is there...
RMW

OK, today I made a CAD file which has all of the stamped linkage pieces as flat cut parts. This is how the EDM will cut them out, they will just need to be bent and have holes tapped for idle, fast idle and adjustment screws. View a JPEG of the pieces at
http://www2.et.byu.edu/~jmv/Carburation/Linkage/EDM%20Linkage.jpg
Perhaps this week I will get to writing the machine code and maybe next week cut them out.
Jake

Oh yeah, there is one other piece but it needs to be turned on a lathe.
Jake

Jake, let me know how it goes. If there is a chance of buying a set, I would be happy to sort all the drilling, bending and tapping out at my end.
simon forsdyke

If possible I am keen to buy a set.

I made my own linkage by tig welding some components from other applications together. Works perfectly, but if I had a chance to have the real thing that would be much better.

The throttle return springs on the OE setups are around the shaft. I could not see how I could replicate this, so I attached short levers and springs to the outer ends of the throttle spindles. I have a photo if anyone is interested.

I made a replica of the choke connector from a solid piece of aluminium with 2 bolts tapped into the side which were then cut off.

The original I copied it from was plastic.

cheers

Ian Buckley

Simon, Ian
I will see if this all works out then let you know. If it does, I will be able to make as many as are needed. Do you just need the synchronizing linkage, or the choke and throttle cable fixtures as well? I have fabricated my own from round aluminum stock turned on a lathe with a hole for the cable to pass through and an allen head set screw to hold it in place. Both of these I can make more off as well. Will you need me to drill and tap the necessary holes and will you need adjustment screws? Just some things to think about. I ordered some stainless plate today so it should be here on monday, and I'll try and cut them out then.
Jake
Jake

Jake

Simon and I am closely following this thread, as I am sure many others are. I am going to be away for a week and eagerly await developments on my return. I am having a week in 'sunnier' Queensland!

Personally I don't need the choke and throttle connections as I am am happy with what I have made. However, I would like the synchronising linkage. If you could drill and tap the holes and supply adjustment screws that would be the best for me.

It goes without saying that I will contribute to any costs involved.

thanks again

Ian Buckley
Ian Buckley

On the factory V8 there are throttle return springs wound round the shaft of each carb plus another spring that pulls the cable back. This last spring is very similar to the *three* return springs that are used on the 4-cylinder HSs.
Paul Hunt

Jake
I deally need all the linkages and the choke piece as I am converting carbs from a Rover SD1. If you are able to supply the complete items with screws etc I will cover all the costs no problems. I appreciate what you are doing here. I reckon you will be able to sell a lot of these around the world as they are not available anywhere.

Ian
Can you send me a photo of the spring setup.
Simon Forsdyke

This evening I finished up the program for the EDM so if all goes well monday, I should have a set in stainless steel that I will test to see if it will work. I will post photos as they become available.
Jake

Hi Jake
How do the linkages come out?
Simon Forsdyke

Simon,
Just today I got the drill the holes so maybe tomorrow I can cut them out. Ill keep you posted.
Jake
Jake

Well, after 2 hours of drilling 18 holes with a 1/16" drill bit in 1/8" stainless steel, I realize now that its something I don't want to do again. The one set that I drilled for was cut mostly today and will have to finish up monday. To all those interested, if you can find someone around in a local machine shop who has a Sodick wire EDM, I will gladly email the program I wrote as well as a coordinate sheet for the holes which need to be drilled, and the specs on what size metal piece to start with. I wish it had been easier and less time consuming, but such is life. I will look around here for someone I could farm the work out to, maybe the cost would still be reasonable. If so, I will make a few more sets to those interested.
Jake

Jake
I would be happy if you could just give me the dimensions of the parts. I can probably make them myself (may not be as high tech as yourself). I have looked at a couple of sites in the UK that do Spark Erosion. They seem to need the files in DXF or IGES format. Is this the format of your file. Is there any way of translating your program into an engineering drawing? I found this program which seems to open DXF and IGES files http://www.trixsystems.com/dcenter.html. Also this one http://www.cimmetry.com/cimweb.nsf.
If you can send me the files, I will take a look.
Send them to simonforsdyke@btconnect.com as Hotmail will not handle any large files.
Simon Forsdyke

The program I wrote is an .NC file, I had to literally write it from scratch on Notepad and change the file extension. I have found two shops here inthe US with the same machine that Im using for the one set, I have emailed both for a quote and will let you know what they charge.
Jake

the pieces are cut out, they are just still a little thick so I may surface grind them to the correct thickness. The program seemed to cut them well. I will see if I can export the cad drawings to a DXF
Jake

Just a picture of the parts, before being bent.
http://www2.et.byu.edu/~jmv/Carburation/Linkage/P3010029.JPG
Jake

Jake
This demo may enable the conversion;
http://www.jssmdx.com/Products/MDXEdit.htm

I have access to Autocad etc if the original drawings are in this format.

Simon.
Simon Forsdyke

This thread was discussed between 15/02/2004 and 02/03/2004

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