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Post by tommydp on Mar 9, 2012 14:29:29 GMT
Hi!
Judging by the "after" picture of the carb I'd say you'll have to adjust the fast idle screw.
It's supposed to be only a very small gap between the screw and the choke lever. It's described in the manuals. Too big a gap means too little air/ throttle opens too little, so you'll have the wrong air/ fuel mixture when choke is pulled out. It'll run too rich. This is your symptom, too.
You could also check by pulling out the choke until it's just about to pull the jet down, ie apply the choke. At this position the idle of a hot engine should be 1000-1200 rpm or so. So the first movement of the choke should increase the idle speed considerably, I'm sure yours doesn't at the present setting and you'll end up with too rich a mixture when using the choke.
Good luck! Regards, Tommy.
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Post by indianajones on Mar 9, 2012 21:22:00 GMT
Cheers Tommy, will give it another look today. Yep in that photo the screw to the choke lever was screwed out a bit and I fixed that soon after  Yes, but at idle you may have richened the mixture to compensate for the better air flow. Engines do strange things. Just a thought have you checked the ignition timing, sometimes a retarded ignition can give symptoms like this. Well I haven't touched the timing since it had been giving me no trouble before the carb came off. Will see how she goes again and might even pull out the timing light to see what's she's at regardless -Andrew |
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Post by indianajones on Mar 12, 2012 20:31:22 GMT
I just got an E-mail from Tony today regarding my 'crab. As you know the PAS is long gone from her, and Tony seemed concerned about a rubber disc at the bottom of the steering column, which needs to be there for non-PAS. I've replied saying I shall look at it, hopefully this week or weekend. Just a little bit concerned now! In other news I've also got my new rear speakers in -Andrew |
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Post by indianajones on Apr 3, 2012 9:12:49 GMT
Not too much to report on lately. Took her in for a WOF, failed on two minor issues: 1. A fuse blew and my tail lights stopped working - fuse replaced and sorted 2. Passenger door button got stuck in and failed to open - This is always happening and I think I have a good idea of what's going on so will fix this weekend Then I'll take her back in for a retest the weekend after and we'll be all sorted! Mr. Wood informs me a box of 'crab goodies is on the way so will update one they get here. Another thing I want to look at is the timing, I'm trying RON 95 petrol in her now and I'm not sure if the timing needs to be adjusted. From reading online and in my books the idea seems to be that the timing needs to be as advanced as it can be with out causing 'pinking'. This is a term I hear/read often, but I can't actually find a video etc to help me know what it actually sounds like, any ideas? Also I need to get on with that dizzy cover like Chris has, will bug him again once his 'crab is all sorted  Cheers, Andrew |
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Post by dave1800 on Apr 3, 2012 9:57:39 GMT
I have listened to some examples on the web but they don't sound anything like a B series engine knocking through over advanced ignition. If you can imagine someone hitting the cylinder head with a small metallic hammer at the same rate as the rpm (all 4 knocking) or half this (2 knocking) which disappears as soon as you ease up on the throttle and reappears as you accelerate again that is it. The classic check is to climb a moderate hill (1in 8 or 12%) in top gear at around 30mph in top gear and if it knocks under full load, retard it in 2 degree steps until it no longer knocks. Rememer that in hot weather or with lower grade fuel it will knock sooner so it is best to err on the cautious side as knocking will destroy the engine very quickly. Whatever you do make sure that the maximum TOTAL advance ie static timing plus the distributor advance with RPM doesn't exceed around 36 degrees. You can ignore vacuum advance as the vacuum will be close to zero on wide open throttle. This is important as engines often seem to idle better with more advance. Let us know how you get on regards David Not too much to report on lately. Another thing I want to look at is the timing, I'm trying RON 95 petrol in her now and I'm not sure if the timing needs to be adjusted. From reading online and in my books the idea seems to be that the timing needs to be as advanced as it can be with out causing 'pinking'. This is a term I hear/read often, but I can't actually find a video etc to help me know what it actually sounds like, any ideas? Cheers, Andrew |
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Post by indianajones on Apr 13, 2012 21:37:04 GMT
Hey lads, a little update: Have taken the 'crab back for her recheck and she passed So all WOF'd and Tax'd now....just in time for winter! lol Another thing I've noticed is since my carb rebuild, whenever I let go of the throttle when driving the needle on the vac gauge goes to 'overrun', is this an issue? I know cars and bikes do it when going downhill etc, but this seems to happen on the flat too? Cheers, -Andrew |
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Post by Penguin45 on Apr 14, 2012 0:41:03 GMT
Er,,,,, Vacuum at the manifold decreases with higher revs? The old vacuum powered windscreen wipers tailed off at higher revs, I think. Mainly a Ford thing.
Congrats, BTW.
Chris.
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Post by dave1800 on Apr 14, 2012 6:10:28 GMT
At high revs with the butterfly closed or nearly closed the vacuum will be at its highest. Opening the throttle wide brings it back towards atmospheric pressure ie a reading of zero on the gauge. Yes, I recall the old Ford 100E hich used manifold vacuum via a tank to work the wipers. Going up hill the reserve in the tank would soon be exhausted and the wipers slow down until they stopped. Great when following a lorry - they didn't have rubber mudguards in those days! Regards David Er,,,,, Vacuum at the manifold decreases with higher revs? The old vacuum powered windscreen wipers tailed off at higher revs, I think. Mainly a Ford thing. Congrats, BTW. Chris. |
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Post by indianajones on Apr 16, 2012 0:35:26 GMT
Cheers lads, that had me a little worried.
Also installing the new throttle cable to the carb seems to have sorted my issue of random jumps of idle speed when starting the car and stopping etc.
But my idle seems a bit 'rough' now, I took the car for a decent 60km spin yesterday and when I got to the lights the idle seemed to drop from 800 to 500 and kinda wobbled between the two and sounded a bit 'off'?
Would this be caused by a mixture issue? too lean?
Cheers,
-Andrew
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Post by dave1800 on Apr 16, 2012 14:15:11 GMT
It could be many things, but if it happened when the engine was thoroughly hot, try lifting the carb piston with the lifting pin about 1/16". If the idle increases it is running too rich, (more likely) if it stalls too weak - not good for the engine. You can also see if the idle improves when you remove the oil filler cap, again this means too rich. Regards David Cheers lads, that had me a little worried. But my idle seems a bit 'rough' now, I took the car for a decent 60km spin yesterday and when I got to the lights the idle seemed to drop from 800 to 500 and kinda wobbled between the two and sounded a bit 'off'? Would this be caused by a mixture issue? too lean? Cheers, -Andrew |
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Post by indianajones on Apr 16, 2012 20:14:08 GMT
Cheers dave, will check this out next time I take her out.
-Andrew
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Post by indianajones on Apr 25, 2012 4:03:17 GMT
Ok, looking at my valve clearances again. Seeing as my engine may not be original, I'm a bit lost as to know what clearance to use. Engine number is: 18H AA H 41062 www.mgcars.org.uk/mgccz/technic/codeseng.pdfMy 1964-71 Autobook says 0.015 for Mk. II, while my 1964-75 Autobook (same publisher etc) says 0.013 for Mk. II I am lost! Haynes book of lies says makes for comment regarding valve clearances past Mk. I's so I assume that they're all 0.013 till the end of production (not including 'S' models). The BL workshop manual in true BL form seems to have gone on strike and only mentions Mk. 1 engines clearances (the folder is from 1972 it seems) It has been suggested my engine could also be from an early Princess. Edit, though the timing marks are on the bottom, so that would suggest a non-princess (later) engine? this souce also suggests that 18H engines were used only in Mk. III's? www.mymg.com/Documents/enginehist.pdf (page 53) I'm tempted to set it to 0.013, but I know if it's too tight I'll naff my engine sad.gif Any ideas? -Andrew |
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Post by indianajones on Apr 25, 2012 6:06:01 GMT
Well just gave it another tune and doesn't seem too successful rolleyes.gif
I'm getting a few 'pops'/'bangs' when going up hill. Would this suggest too lean?
The process I am doing is this, warm the engine up.
Set the idle speed to 600-800rpm (trying to get 700)
Adjust the mixture nut until when I lift the lifting pin 1mm the engine note barely changes.
Am I missing something here?
I figure out what I might of done wrong with the choke cam setting, but I haven't bothered looknig at this yet as I wish to get it tuned first.
-Andrew
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Post by indianajones on Apr 28, 2012 4:55:09 GMT
Before working on the tuning I got around to installing my new rear engine mount. As you can see the old one was a bit past it. img213.imageshack.us/img213/717/rimg0152.jpgimg526.imageshack.us/img526/5227/cimg0546s.jpgSo out she came and in went the lovely new one sent to me by Tony. I could of got a NOS one, but decided to get the slightly more costly custom made one, they're not meant to fail, or so I am told. I hope not to find out lol img803.imageshack.us/img803/6417/rimg0148.jpgimg209.imageshack.us/img209/4295/cimg0547.jpgWill get a front mount also no doubt down the line. Then it was on to the tuning. Checked the clearances again for 0.015, two were a little bit out, but otherwise fine. Doing this required the plugs out of course, and this is what they all looked like, black as the ace of spades. These went in before my carb rebuilt (or at least that's how I remember it, work and tech have taken up most of my mind lately lol). So she must of been very rich to foul them up so quick. Cleaned them up and popped them back in. img545.imageshack.us/img545/4643/rimg0153.jpgThen I fired here up and gave the tuning another go, got her a little bit rich and then took her for a spin, she seemed to be purring like a kitten so it seems at this moment it could be all good. Will keep an eye on it and report back. Another question I have is how does one set the choke up? this is proven somewhat difficult/confusing. :unsure: I have re-read Tommy's post above and will check tomorrow. ;D -Andrew |
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Post by dave1800 on Apr 29, 2012 2:34:19 GMT
Andrew Make sure that when you push the choke cable in that it fully closes ie that the jet is at its highest point. There should be a small amount of slack, say 1/4" (6mm) before the choke mechanism is activated. If in any doubt disconnect the cable, push the jet to its highest point and then reconnect the cable. Make sure that it is free by pushing it in and out several times to check for any sticking. I don't like the popping and banging going up hill. It could be many things. Check the compression to make sure there isn't a valve problem. To be safe set the tappet gap at 0.015". The later engines with the smaller tappets were supposed to be set at 0.013" but the engine will suffer if the gap is too small and different people can get different readings so err on the safe side. Remember setting the mixture is the last thing to do after you have set the tappets, engine timing, checked for air leaks etc. Plenty on the "Tommy thread" Regards David Well just gave it another tune and doesn't seem too successful rolleyes.gif I'm getting a few 'pops'/'bangs' when going up hill. Would this suggest too lean? The process I am doing is this, warm the engine up. Set the idle speed to 600-800rpm (trying to get 700) Adjust the mixture nut until when I lift the lifting pin 1mm the engine note barely changes. Am I missing something here? I figure out what I might of done wrong with the choke cam setting, but I haven't bothered looknig at this yet as I wish to get it tuned first. -Andrew |
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