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MG TD TF 1500 - Rough Warmup Running
|Been ignoring this for a long time, but shouldn't any longer. I can tolerate it, but I'm sure that the better half wouldn't like it. For what seems like forever, cold starting, i.e., engine shut off for hours, or overnight, or longer, starting is accomplished by pulling the choke out about 3/4", turning on the ignition, wait until fuel pump stops clicking, and then activate the starter until the engine fires up. Rather rough running, but handled easily by pushing the choke in a bit and blipping the throttle until it's running smooth enough to get moving. It appears to me that, in theory, applying the choke should allow the cold engine to run smoothly. I don't recall reading anything in tuneup procedures about choke adjustments for anything other than obtaining clean sparkplugs when motoring. What am I missing? The bride of 57 years is about to start driving Lazarus a bit. TIA. FYI, after those first couple minutes he runs like a top. Bud|
|Bud, mine does exactly the same thing. I always considered it "normal". Isn't that what old cars with manual chokes are "supposed" to do? Maybe the cars don't need choking, hence the roughness?|
|Thanks for bringing this up BUD. I have the same problem. that's to say: with a cold start I pull the choke to the max and turn the starter on have to do this a few times the engine gives a few puff's on one or two cylinders and finally there she comes on . Starting warm / hot engine ? she start's with no problem apart from vapour lock so now and then.|
Any idea's here gent's
|All sounds normal to me, thank your lucky stars you are not dealing with an automatic choke, then you would be scratching your head.|
|We are just spoiled with EFI. George|
|For what it is worth, Mine runs smooth from the beginning. Gradually runs rougher as she warms up and idles above normal speed until I remove the choke. Regards, tom|
|My TD has always been fairly constant in starting since I restored the car. Like Bud's approach, I pull out the choke knob about 3/4 to 1 inch and she fires pretty quickly. I have an older Pertronics for what that's worth. Within ten or fifteen seconds of running (in Summer), I twist the knob and allow the choke cable to retract about one or two of the notches. Then repeat that as the engine begins to warm up. I work mostly by sound and feel as I drive until the temp indicator begins to show some life. Just one of the lucky ones, maybe.|
|There is a good possibility that the fast idle adjustment screw is not opening the butterflies early enough.|
I would also check that the butterflies are synchronized.
|Bud - If your carbs are anything like the ones in our TD, the fast idle lever is so worn and the pivot on the carb body where the lever resides is also worn to the point that I have to have the choke pulled nearly to the third notch before it has any effect on the engine. The result is that I have to pull the choke cable out three notches to get the car started, then drop it to the second notch immediately of the carbs are over rich and it only takes about 15 seconds that the second notch is to much choke, so I wind up on the first notch that doesn't have enough choke and when I take off, the engine spits at me. Fortunately, unless it is a very cold day, by the time I get to the signal at the top of the hill, it has settled out and I can push the choke knob all the way in. One of these days I am going to quit threatening and send the carbs to Dave Braun for an overhaul. Cheers - Dave|
|Dave, it sounds as if you've been looking over my shoulder. You're right, it's been some 20 years since Jim Taylor did the carburetors for me.|
GBIII is right about modern EFI systems. We do get spoiled. But, even my Honda snowblower has a choke that works fine - starts, runs fine, push it in gradually as the engine warms up.
Time to tinker with some hardware. Thanks folks, Bud
|Bud and Dave,|
In the years that I have been driving vehicles starting with a Farmall Cub tractor in the late 40's chokes have always caused rough running of an engine at idle. My TD has done the same thing for as long as I have had it (over 40) and still does it even with the supercharger. If your engines are running normally at temp then I would suggest that the phrase "don't mess with success" applies.
This thread was discussed between 10/08/2015 and 11/08/2015
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