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MG MGA Mixture control linkages stuffed! BBS discussion at MG-Cars.net
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MG MGA - Mixture control linkages stuffed!
| You may have seen my earlier post about trouble starting my '60 roadster after a couple of weeks in the bitterly cold Aussie winter (3-15C or 37-59F)! I have now checked whether the jets are being pulled down when I pull the choke out - all that this is doing is taking up the wear in the linkages (thanks John, Richard & Cam)- the holes and pins are worn excessively (stuffed). What is the best way to resolve the problem - try to reconditioning levers or just by a new set of Moss levers and pins? Any comments about replacement parts quality or tricks with replacement appreciated. I now have plenty of time to work on it as we are out of the World Cup - I suppose you guys in the UK, Switzerland, US and Canada are in the same boat! Regards Mike |
| Mike Ellsmore |
| Mike Even when new there is a lot of slack in linkages - at least there was on mine! I take out nearly all of this slack when I connect the cable. This results in only about the first half inch of choke pull doing nothing. Incidently, the good book says to rotate the inner cable counter clockwise (depending on how you view it!) a few times to aid locking of the choke pull. Steve |
| Steve Gyles |
| Burlen Fuel Systems keep all the parts www.burlen.co.uk. What football? Terry |
| Terry Drinkwater |
| Mike, If you are the least bit handy (does that sound like a challenge?), the worn holes can be rebuilt easily. Drill out the worn hole with a drill large enough to make it round. Make it a standard size. Buy a brass dowel at the hardware store that fits the hole you drilled. Cut a piece off that is slightly longer than the lever is thick. Using plumber techniques, sweat-solder it in place filling the hole. Dress the front and back of the plug on a sander. Then drill a new hole in the lever. It really is pretty easy to do. It is cheap, quick, as good as the original, Indistinguishable from the original when assembled and you can say.. "I did it". And no waiting for the parts to be shipped. Been there, Done that! Chuck |
| Chuck Schaefer |
| I also did exactly as Chuck describes. The difference in starting from cold was amazing. |
| John DeWolf |
| Mike, If you do buy the brass carb. levers get them from Burlen. I originally bought Moss and they were very poor - holes too big - twisted along the length - so I returned them. The Burlen ones are made in the UK and are excellent quality albeit a little bit more expensive. Mike |
| m.j. moore |
| Chuck Excellent idea. Winter job for me. Steve |
| Steve Gyles |
| Note that one of the holes (link to body) must be oversize to allow the fast idle to operate before the actual jet movement. On a new lever, starting from the return spring end, the holes are as follows: Return spring hook, jet clevis hole =.188, link to body hole =.320, fast idle link hole =.188, hole(s) at end =.188. When correctly adjusted, there will be almost no "does nothing" travel, even if the holes are quite worn, there must on no account be any binding in the linkage. The first 1/2" of travel operates the fast idle cam, then the jets move. If your first 1/2" "does nothing" then you either have the cable too loose, or the fast idle cam/screw is not adjusted correctly. FRM |
| FR Millmore |
| FRM I know what you are saying, but I intentionally leave a little 'slack' in the system to reduce the chance of there being any residual choke when the choke pull is fully in. The fast idle cam works absolutely fine as soon as the cable takes up the final bit of linkage slack (about half an inch of cable pull). It's worked fine for me for the last 9 years. Steve |
| Steve Gyles |
| Steve- As long as you understand what/why you're doing, it's fine. What I used to see a lot was if the cable had too much slack, people would pull it out past the self locking mechanism, which then wouldn't work. When they tried to force the knob back in, they would bend or break the rigid part of the cable pull. When I first learned to adjust the fast idle and cable, I was told "Put a nickle in it, get 1500rpm". That allowed about 3/32-1/8 slack and enough travel to get 1500 without moving the jet, in the diameter of a nickle - or .835 pull, for you who haven't got nickles. In practice, I find that 1500 is usually a bit fast, so I set it to about 1200/1300 at that point. FRM |
| FR Millmore |
| FRM My apologies. Duff gen on my part. I decided to measure my 'slack'. Tighter than I thought - 0.091 inches! |
| Steve Gyles |
| Thanks Guys - what I like about this site is you post a query, go to bed for the night and when you wake the answers are all there - It works that way here with the time difference! Mike |
| Mike Ellsmore |
| Steve, Your advice on pre-twisting the cable is a good one, I did not do that and cannot, for the life of me, get the choke cable to "lock" in position. I have been thinking that twisting the cable was the way to go. I never read the "good book" on that subject. God to know that someone knows how to read! Chuck |
| Chuck Schaefer |
| Chuck I guess there a lot of 'good books'. This one is a potted MGA & MGB owners workshop manual, published by Brooklands Books Ltd. I bought it so that I had data on the MGA, MGB engine and brake calipers all under one cover. It also is convenient to keep at work as it does not attract too much attention, measuring only 8.5" x 5.5"! Steve Steve |
| Steve Gyles |
| Steve, Yeah... That one is in my library. It has a nice plastic coating on the covers that clean up easily. Since I have a virtually stock MGA, I generally refer to my FSM. But honestly, Since the rebuild, I haven't had to refer to it in over 5 years. Today's our 4th of July holiday, so I don't have to go to work. I might just find some time today to sneak out tho the garage and twist that cable. Cheers! Chuck |
| Chuck Schaefer |
| It's worth mentioning that Burlen Systems are the owners of SU (and Zenith too), so any parts you buy from them are going to be genuine SU parts. Buying a carburettor rebuild kit from them was a great deal cheaper than from Moss (unfortunately I only discovered that after I had bought mine). Richard. |
| Richard Ross |
| Steve, Pardon my ignorance, but how does twisting the cable make the choke knob lock in position. Looking from the knob end you twist knob anticlockwise (counter clockwise for our US brothers) to lock. Locking from the cable end you twist the cable anticlockwise also before tightening the clamp nut - is this correct? Mike |
| Mike Ellsmore |
| Hi Mike, If you need carby parts or want a complete rebuild,we have one of the world's best suppliers here in Australia.A company called MIDEL PTY. LTD.supplies many owners worldwide with v good original quality gear including fuel pumps.They are located in Lakemba,NEW SOUTH WALES. I have heard that Bill Bressington the owner of the business has recently passed away.A tremendous bloke and great,highly knowledgeable SU enthusiast over many years. I have dealt with them on carby parts for my TF's. Cheers Rob. Grantham |
| Rob. Grantham |
| It is a bit of odd engineering, but the hole is supposed to be (quite a bit) too big. Sloppy looking thing, but that's the way it works. |
| Tom |
| Mike Re twisting the cable. Good question, well asked. I don't do it on my cable as I have never had any problem locking the pull knob. I recall doing it on my old MGTC (square rigger). I only mentioned it here as a quote from a book as someone was having to put a wedge under the pull to hold it out and I thought that this may be an option that would help solve it. I also noted your comment that you twist your pull anti clockwise to lock. I thought mine twisted clockwise so I have just been out to the car park to check. It locks in either direction! Am I alone in this or is it standard? Regards Steve |
| Steve Gyles |
| Seems to me that Steve is right, it locks eiher way, and I think my tendency was always to lock them clockwise. The important point is that: Cables have a built in twist in the lay of the cable, and any twisting you do on installation should tighten this twist. I think this will normally be anti-clock from the carb end, and the knob will then naturally rotate itself clockwise when pulled out. The effect is then that you don't have to turn the knob at all to lock it, but will have to turn it anti-clock to unlock. FRM |
| FR Millmore |
| My mistake, I got my anti and counter clockwise mixed up trying be politicaly correct. Yes my choke does lock when you turn clockwise (but not very well - a bit more twist needed it seems). Now it makes sense about the lay of the rope construction (you wouldn't think I spent two years at coal mine as the engineer in charge of aerial ropeway system - Langs lay and all that stuff is coming back to me). I am still not sure how the actual lock works - I understand the cable twisting makes the knob rotate but what causes it to lock, it is essentailly a pin in a bush and it wouldn't lock if they are concentric, is the bush oval shaped so it wedges? Sorry for being so pedantic. Rob thanks for the tip on Midel - since getting back into sports cars after many years I am finding we have some real experts here in Oz. Mike |
| Mike Ellsmore |
| Mike- If you pull out the knob and examine the shaft, you will see that it is flat on one side, but has a smaller diameter round bit in the center. There is a small piece in the housing which matches this shape - a kind of thick bodied C, which is retained in a slot by a semicircular flat spring around the housing. When you turn the shaft, the little c shaped piece is forced up against the flat springy thingy, locking the shaft in place by friction. There are variants on this, like a shaft with a groove and a ball instead of the C shaped piece, but they all work the same way. FRM |
| FR Millmore |
| "bitterly cold Aussie winter (3-15C or 37-59F)" - HA! I think you meant to write,"temperate Ausie winter" ;) |
| Fred H |
| Thanks FRM understood. |
| Mike Ellsmore |
This thread was discussed between 03/07/2006 and 06/07/2006
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