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MG Midget and Sprite Technical - Sticking Choke

I have a 1977 1500 which originally had the waxstat jets on the carbs. I swopped these for the normal jets using SU's Jet Conversion Kit about three years ago.

I have recently had trouble with first the front carb jet sticking down a bit after using the choke. The rear carb jet is now doing the same.

It's a bit of a pain having to stop, open the bonnet, and push the two jets up to their rightful place every time the choke has had to be used.
I presume this is to do with the different linkages supplied with the conversion kit.

Has anyone else had similar problems?

I was even thinking for going back to the waxstats!!
Tony Wood

Tony,
when I had my carbs off last year I found one had a hesitant spot on the jet on checking the movement after cleaning by pushing and releasing. I cleaned it and checked it two more times before it felt like it moved freely. I didn't take the bottom of the carb apart as at the time parts were out of stock and any way I was already too pissed off with the car.

On putting it back on the car and trying to get the carbs sorted and car running right I eventually discovered after road test runs and back-aching head under the bonnet making adjustments that among other things the bloody carb was intermittently sticking again.

I can't remember how many more times I had the carbs off cleaning and checking but eventually with this and reasonable length test runs it no longer seemed to stick.

No magic answer I'm afraid other than clean and more regular use.

I had intended at that time to replace more parts on the carbs but they weren't available then and I farted about with the carbs and other stuff partly because of not knowing the carb was still intermittently sticking that they can stay as they are as long as the car goes well.
Nigel Atkins

Thank you Nigel

Looks as though I'll just have to live with it. I have tried a touch of oil - but of course it doesn't last long.
Tony Wood

Tony, oil may have acted to catch dust which has accumulated around the screw in the plastic pivot point at the bottom of the jet, and on the sides of the brass jet itself. Rather than adding more oil try a good burst of carb cleaner spray, or of brake cleaner. Also, do you have the correct choke cable - it works better if the inner cable is a single solid wire, not a flexible twisted bundle type one.
GuyW

Tony,
if it eases with lubrication then that at least has confirmed it.

I'm with Guy about cleaning the existing oil off now to also take off any dirt and reapplying a very sparing amount but not on the jet itself I think.

A trick I now use is to set the choke with the accelerator pushed down that way you're taking some of the resistance off the carbs linkage and choke, this is before turning the ignition, and fuel pump, on.

You can do this several times before turning the ignition on, allowing the choke cable to pull back to off each time which hopefully gives more exercise to the set up and less sticking.

Only yesterday I saw a John Twist video where he's oiling the carb linkage with light oil and it drips on to the manifold then burns off when you start the engine, this is nasty stuff to breath, I know I had it once.

I apply the oil via dipping a small screwdriver in oil and then letting it one drip at a time on the linkage and working it in but then I think I ought to try white lithium grease but it doesn't seem to distribute well and attracts dirt so never do. I've also tried GT85 - I'm not sure what's best other than being sparing.

I agree a solid inner cable is better but I'm not sure who sells them.
Nigel Atkins

Tony, if you want to go back to the original jets but don't want the waxstats you could do the 4p conversion. This involves removing the waxstats and replacing each with 2 X 1p coins, they're a perfect fit.

Bob
R.A Davis

The early cars had solid choke cables rather than the bowden cable of later cars. With a solid cable you don't need the twist-lock function and pushing the solid cable is more effective in releasing the choke. But you do have to put up with a simple "C" on the knob.
Rob
MG Moneypit

Thanks Guys for all the comments.
1. Yes, I've got a solid wire for the choke cable and it's well lubricated.
2. Carb/brake cleaner is a good idea and I'll be doing that shortly (after wimbledon and the footy).
3. Originally the waxstat jet worked fine with the choke operation, but I was persuaded to update them to standard jets by using the converson kit. This of course comes with a different set of linkages which I believe are the source of the problem.
4. Thank you Bob for the 4x1p trick for the waxstats. I will seripously consider this if I continue to have problems and if I can find the discarded linkages that are somewhere in my 17th C barn of a garage.

What would we do without this forum?
Tony Wood

Tony,
if you have a solid cable with more modern linkage could that be the problem. The later type of cable locks out against the pull of the return springs and the combined efforts of the springs is quite considerable.

I must admit I'm lost on 1500s, then yours might be RHD so different cable arrangement, and you've got different linkages. Perhaps it's all about the angle of the dangle.
Nigel Atkins

On T Series MGs the two carb spindles are joined by to small, "U" shaped metal clamps. These are actually small universal joints to take up any misalignment of the spindles and they must be fixed at 90 degs to each other or the throttle action will be stiff. I know that Spridgets have a different system but if an accelerator or choke is stiff or notchy it could be the spindles don't align due to gasket thickness or the need for the carbs to be rotated slightly by slackening the fixing bolts.

Jan T
J Targosz

This thread was discussed between 07/07/2021 and 10/07/2021

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