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MG MGA - Choke Issue

I fully restored (a ground up restoration including carbs rebuilt professionally)my 1960 MGA 1600 a number of years ago and the choke has never worked quite correctly. With the choke fully pulled out the car will not start when cold without the use of starting fluid. When pushed in the engine completely refuses to start so I'm pretty sure it is having an effect. Once it stumbles to a start and is running (barely with me "goosing" the accelerator) the engine finally smooth's out after 10-20 seconds. The engine RPM increases as it warms up as expected. I decrease the choke until normal idle is achieved when the choke is fully pushed in. The car idles and runs great when warm and starts like a champion - when warm. Does anyone have any ideas to correct this? Thanks, Keith
K. G. Meyer

The use of starting fluid , to start , means (to me), that you are not getting fuel into the cylinders, when cold....
Your carbs probably run pretty lean, when warm.
Take a look at your plugs....If the porcelain is tan, and the spark tip is clean, then your settings are probably correct.....If the porcelain is white,and spark tip looks a little distorted, then you are too lean.(If black and sooty, then too rich...but it doesn't sound like that is your problem).
But, before you adjust anything ,I would first look at the mechanical settings on the choke "cam"...
Look at the choke "lever" and the choke adjustment screw.
When the choke cable is all the way in,(toward the dash), there should be a very small gap between the tip of the screw and the cam....With the choke pulled out, the screw should be riding on the high point on the cam....(and the idle screws should be up , off of their seats).
Since every engine is a little different, you'll need to find the sweet spot.
The other possibility, is that the linkage isn't being pulled upwards enough , by the cable......How loose is your choke cable, at the linkage?...If it is too loose, it is not richening the mixture enough....The manual tells you how much slack there should be in this cable...(I think it's about a 16th of an inch)....
Anyway, those are the places that I would start.
Edward
Edward Wesson 60MGA

I needed to add, but couldn't , that it's possible that the jets are so tight in their bores, that they are not moving....Check to see that the jets move up and down , freely.
Edward
Edward Wesson 60MGA

Sounds like the choke linkage is not adjusted properly, and not enriching fuel mixture enough for cold start. Unfortunately the Workshop Manual doesn't tell you how to do i. But I do, so read this first:
http://mgaguru.com/mgtech/carbs/cb102.htm
http://mgaguru.com/mgtech/carbs/cb103.htm
Barney Gaylord

"Choke pulled fully out" means different things to different people. I had a friend with a similar problem in his Morris Minor. When I pulled the choke fully out he gasped, having no idea it pulled out that far and so never tried. His car always starts right up from cold since!
Neil McG

Edward: The cable does not appear to have too much play. I've adjusted the screw to barely touch the cam but with the cable fully pulled out the cam never reaches the high point of its potential travel, it comes up about 1/4-3/8" short of reaching the high point. On the cam are three holes numbered 1, 2, 3 running clockwise from the lower part of the cam. Currently there is a link pin in hole number 1. However, it appears that for the cam to reach its highest travel there should be a Zero hole or in other words the cam should move further clockwise so the cam can rotate clockwise and to the top of its travel with the cable fully pulled out. Maybe I'm seeing this wrong??
K. G. Meyer

Neil: Saw your comment, pulled hard enough to rock the car, thought the knob would come off. There is only 1/2" of choke cable travel wen measuring from the base of the knob to the instrument panel. Does that seem short? Keith
K. G. Meyer

K.G.
My cable comes out about 2+ inches....

Pull the cable all the way, then lift the linkage by hand , and see if it comes up further....
I'm beginning to believe that your jets are stuck in their bores.
You'll have to remove the air cleaners, and disconnect the choke linkage from the bottom of the jets...
Then try to move the jets by hand...If they are really tight, that is your problem.
Edward
Edward Wesson 60MGA

K.G.
You have answered your own question. If you can pull the linkage up after you have pulled out the knob, then you are not adjusting the slack out of the cable, or not pulling the knob out far enough.
Before you clamp the cable, i.e before tightening the nut on to the cable, you must pull up the linkage to take out the slack. It is one of those situations where you need three hands!
Your dash knob should only come out about 2 inches max.
The cam linkage should be in the middle hole. The other holes are for extreme conditions, i.e. extreme cold or extreme heat ambient temperatures. The screw should not touch the cam when the choke is off.
Peter.
P. Tilbury

Thanks Barney. Looks like you have answered my cam question. Will give it a read and work through the process. Keith
K. G. Meyer

Keith
Have you looked at your plugs?....Can you post a closeup of one of them?
Edward
Edward Wesson 60MGA

Edward: Here is a photo of No. 1 plug. It sure looks like its running rich to me. Champion N5 C Keith

K. G. Meyer

Keith
The porcelain looks tan....The spark tip is clean....
Looks fairly normal to me....Soot will develop when idling....
Next step has to be to check your jet movement...Aggravating , but necessary.
If they feel really tight, then that is your problem....If they move freely, (not loose, of course), then I think I would go on to the timing, and make sure you don't have too much spark advance.....
Barney has lots of info on timing in his "handbook".
Hope you'll post when you get it solved.
Edward
Edward Wesson 60MGA

"Neil: Saw your comment, pulled hard enough to rock the car, thought the knob would come off. There is only 1/2" of choke cable travel wen measuring from the base of the knob to the instrument panel. Does that seem short?"

Yes, absolutely too short! That would appear to be the whole problem right there. The question is why does it not pull out further. Try pulling the cable directly at the carbs to try see why it is so stiff. Maybe stiff jets. If they are not moving that would explain everything.
Neil McG

1st (easy) part of pulling on the choke knob just opens the throttle plates for fast idle. There is a harder section beyond that, that lowers the jets. It sounds like with the 1/2" movement, you are only pulling the fast idle and not thru the jet movement part of the action. Easy enough to see if you have someone look under the carbs while you pull on the choke knob. the jet should drop down.
Chuck Schaefer

This thread was discussed between 12/02/2014 and 14/02/2014

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