spiny
Club Retro Rides Member
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I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 17, 2011 11:39:45 GMT
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hello everyone  I'm at the point where i'm proper confused with my mg and don't knwo what to try next, so i'm asking you lot to suggest a course of action thats sensible, rather than my 'change everything at the same time and get nowhere' approach ... as it stands: I have a '70 MG Midget with a 1275 engine frm a Marina in it. The engine was from ebay and had no history other than 'it worked when i had it' it had no carbs, so initially I fitted the twin SUs from the original (siezed through standing for 25+ years) engine and had a go like that. It would run, but poorly, would idle very high and pop through the carbs if you revved it. it would pootle about my garden ok though. next up I tried playing with the timing - this is where it gets a bit complicated. as it's a marina engine, the front pulley cover has timing marks at the top, but I had to swap the pulley cover for the MG one in order to use the engine mounts, so now I have no timing marks at all. so question 1: whats the best way to make some timing marks - i.e. find TDC etc, measure the pulley and work out +x amount of degrees ? next up, I bought a HIF38 carb off ebay and fitted that, pretty much the same result, plugs sooting up, popping through carb etc. then I checked the fuel pump and regulator (facet leccy and some italian named reg that I can't remember) turns out the pump was probably too powerful and the reg was wound all the way out, so, a new low psi pump and adjustment of the regulator happened. now the plugs don't soot up but the poor running is still there. next up in my 'throw money at it' is an Accuspark Distributor - i am about to fit this today, but need help with question 1 up there ^ so question 2: is it likelly to be an air leak / breather problem ? I've gasket sealed everything I can think of. question 3: or is there some weird coincedence where the old carbs are worn out and the new one had the wrong needle, both cases giving the same poor running ? I have the Vizard book, if that helps cheers for reading this far, please help me ! I'm fast approaching the stage where I just buy a recon engine and stay in for a few months, but the a series is hardly complicated and i don't want to let it beat me. |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 17, 2011 12:42:00 GMT
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bah, looks like i bought the wrong accuspark - i got the vac advance for MG ... obviously. but the marina engine has the spin off oil filter in the way ... it ran ok with it fitted though - pics in a bit gone back to the stock marina dizzy now, the engine will run with the choke on, but just dies as soon as the the choke is off. i'm sure it's warmed up enough, been running for about 10 mins ? don't have the temp guage setup yet, the mg is capillary, and the marina is electric .. |
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Sept 17, 2011 14:58:44 GMT
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Hi Phil. If it ran OK with the new one fitted, is your problem not going to be somewhere in the old ignition wiring or distributor? Good points and condensor and correctly set up?
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...proper medallion man chest wig motoring. |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 17, 2011 15:21:43 GMT
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I meant to say it ran, but still badly with the new dizzy in place but a development: looks like one of the plugs is duff, engine note changed when taking three out of four off, but not for the fourth. swapped the plug to a different cylinder and the same thing, so i'm off to get a new set of plugs and see how that helps |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
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Club RR Member Number: 167
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Sept 17, 2011 16:08:05 GMT
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right, a new set of plugs and it's running a lot stronger though still won't idle and is popping away merrily. But I expect thats due to me messing with the carb and dizzy, so back to square one there, but at least with one now known working element. however, I'd still like some help on how to find TDC and time it properly. |
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Sept 17, 2011 16:38:33 GMT
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a relatively simple tool to make for finding TDC was described in PPC mag a few months ago. Get that old duff sparkplug, and (with a suprising amount of effort!) drill it out to accept a piece of threaded rod, the thicker the better, so there's minimal chance of it bending. Weld a suitable nut to the top of the hollowed-out sparkplug. Thread the rod into the sparkplug, with about 10cm-ish poking through. Lock it in place with another nut, and install it into the no1 cylinder. Turn the engine clockwise, until it hits the "plug", and make a mark on the pully, and the block to show where they line-up. Turn the crank counter-clockwise, and mark the block where the mark on the pully lies. Remove the "plug", and move the crank so the mark on the pully is halfway between the two marks you made on the block. The crank is now at TDC  Works on pretty much ANY petrol engine, as long as you can get to at least ONE sparkplug (two will be perfect, two will just be 180 degrees out - just mark the opposite side of the pully!) For yours, if you still have the timing pointer on the engine, file a little groove in-line with that on the pully. |
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You're like a crazy backyard genius! |
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Sept 17, 2011 16:39:18 GMT
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BTW, have you tried just wildly swinging the dizzy around, to see if it improves the running?
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You're like a crazy backyard genius!
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 17, 2011 17:31:21 GMT
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^ many many times  I haven't been back out today (organising food for relatives at the moment) but I'm hoping that the duff plug was the case of the poor / no idle. also, here is a pic of the new dizzy and the oil filter:  the midget engine has a take off there, but the newer marina has a spin on filter instead. do you guys reckon a remote filter housing might help here ? |
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,538
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Sept 17, 2011 20:14:34 GMT
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so question 1: whats the best way to make some timing marks - I.e. find TDC etc, measure the pulley and work out +x amount of degrees ? Sounds good to me. There's really no point spending lots of money on various things if you have no idea where the timing is. The new dizzy would still need to be set in the right position. Ideally you want to make a mark on the pulley where No1 piston is at TDC and a corresponding mark on the timing cover or a new bracket of your making or something. Then, as you say, work out how much of the circumference of the pulley is the correct advance angle and make another mark (9deg static, 12 deg stroboscopic at 1000rpm according to the manual I have). Once you've got the timing set right (and points gap correct) then you know its right and can move on to other things if there's still a problem. Carb needle should make no difference to any idle setting as they are all pretty much identical at the "thick" idle end. |
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Follow your dreams or you might as well be a vegetable. |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 17, 2011 20:38:48 GMT
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so question 1: whats the best way to make some timing marks - I.e. find TDC etc, measure the pulley and work out +x amount of degrees ? Sounds good to me. There's really no point spending lots of money on various things if you have no idea where the timing is. The new dizzy would still need to be set in the right position. Ideally you want to make a mark on the pulley where No1 piston is at TDC and a corresponding mark on the timing cover or a new bracket of your making or something. Then, as you say, work out how much of the circumference of the pulley is the correct advance angle and make another mark (9deg static, 12 deg stroboscopic at 1000rpm according to the manual I have). Once you've got the timing set right (and points gap correct) then you know its right and can move on to other things if there's still a problem. Carb needle should make no difference to any idle setting as they are all pretty much identical at the "thick" idle end. excellent, thanks it's just irritating with the midget that you can't easily see the pulley, let alone get a socket on it to spin the engine ... I have a spare pulley that I can meaure though, so once I have TDC, it shouldn't be too much hassle to make new marks. finding the duff plug has given me more enthusiasm to get back into it. for the last six months or so I've just felt like I've been going round in circles ... |
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Sept 17, 2011 20:48:54 GMT
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You can get a pretty good idea of where TDC is with a stick through the spark plug hole on cylinder 1. Just rock the crank around using a spanner on the crankshaft pulley. When it gets to the top there is normally a flat spot before the piston starts to travel back down the bore. The flat spot lasts for quite a while relatively speaking. You can mark where the flat spot starts and where it ends. i.e. where it stops going up and starts going down. In the middle of the flat spot is absolute TDC. If you have the two points marked on the crank pulley or flywheel or wherever then you can put a line in the middle and you've got your zero mark.
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Sept 17, 2011 20:50:50 GMT
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Oh by the way...
Have you done a compression test on this motor? A leak test is better but a compression test will show up more serious flaws.
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Sept 18, 2011 7:54:07 GMT
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Have you got the firing order right? If you've transposes two leads (- easy to do) it would run with all the characteristics you're describing.
Ask me how I know.....
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ChasR
RR Helper
motivation
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Club RR Member Number: 170
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Sept 18, 2011 10:12:14 GMT
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My line of thought is with Seth's here. Until you know what the timing is at, you may be on a road to nowhere. Sounds silly but do you have the Midget crank pulley, which could (with checking) give you the timing marks you need?
I would also check the firing order. All manner of strange/pooping issues can occur.
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 18, 2011 10:20:20 GMT
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My line of thought is with Seth's here. Until you know what the timing is at, you may be on a road to nowhere. Sounds silly but do you have the Midget crank pulley, which could (with checking) give you the timing marks you need? I would also check the firing order. All manner of strange/pooping issues can occur. no, i have the marina pulley with the midget chain cover, the marks don't line up. If I'd known all this when i swapped the cam covers over, I would have used the midget pulley as well I'm going to find TDC and make my own marks, and if confusion still occurs, I can always pull the engine and swap the pulley, but I don't really want to do that. I think the leads are in the right place as now I have new plugs, removing each lead in turn makes the revs drop. |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 18, 2011 10:21:49 GMT
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Oh by the way... Have you done a compression test on this motor? A leak test is better but a compression test will show up more serious flaws. not yet, I bought a tester for £1 at a car boot a month or so ago, but it goes up to 25000psi or so, so not much use for a car A 'proper' on should turn up this week. |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 18, 2011 12:39:14 GMT
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neat seems to be running reasonably well now ran it on the choke until it warmed up (top hose got hot) then adjusted the main jet until it would idle at about 1000rpm then took it for a short drive around the garden, which is just enough room to back out the garage, three point turn, then drive in again still lots to do - i need an airfilter, then redo the mixture after fitting that, cheers all |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 18, 2011 16:04:33 GMT
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it's working  |
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Sept 18, 2011 19:01:35 GMT
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Cool. Looks like you got your work cut out though. |
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spiny
Club Retro Rides Member
Wiki Admin
I am abivalent towards car electrics ...
Posts: 1,331
Club RR Member Number: 167
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Sept 18, 2011 21:36:47 GMT
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Cool. Looks like you got your work cut out though. it's nearly finished |
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