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Post by tommydp on Jul 31, 2011 17:21:06 GMT
Had it idling for a long time now, tried fuel supply by an electric pump directly from a can. Same stalling after a while, coil hot but I'm not sure that matters any more, mixture changes as before.
Looking at the plugs afterwards, number one is a bit wet without any debris. Insulator white as new. I'm 99% sure it's wet from petrol, smells like it. No smoke when idling. Piston top number 1 wet. Plug 4 is black dry soothy, piston top 4 drier than one, dryish carbon when scraping lightly with a screwdriver. Plugs 2 and 3 are dry tan coloured, piston tops as number 4, dry carbon. I seem to remember piston 2 and 3 would run richer due to the fuel robbing, but perhaps I've got it wrong.
Forgot the time, but at least the servo doesn't hold vacuum for 15 minutes. Pedal hard. I'll check at ten minutes later.
Well, holy cow.. I'm getting lost:-)
Regards, Tommy.
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Post by tommydp on Jul 31, 2011 20:57:49 GMT
Here I am again.. I guess people are getting fed up with the troublesome Norwegian crab:-) I am, too..
However, I'm not sure it's the car's fault.. I must be doing something wrong. The clue is that the only engines I've had trouble with are those I've changed the timing chain on..
I've gone through the enormous amount of posts I've done, regarding earlier engine and the previous hot camshaft in present engine, which was badly timed etc by the company..
Interestingly, some problems were present on the other cam too, as well as the previous engine.. Cylinders 2 and 3 running leaner than 1 and 4, which I believe is the wrong way round. Fuel filter full after driving, hot coil. Even hesitation at steady 70 kmh and downhill occured on the hot cam when it was 10 degrees out. Inlet then opened at 25, which I corrected to 35. I believe it got better then, but the idle was the biggest drawback on that cam.
So, am I doing something fundamentally wrong, perhaps. I'll check the servo tomorrow, and I'm tempted to get into the timing gears again...
Regards, Tommy:-)
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Post by dave1800 on Aug 1, 2011 0:38:21 GMT
Hi Tommy
Hope you managed to get some sleep! You cannot be far away now, honestly!
My advice is:
1. Blank off the servo, before the non return valve to be 100% certain it is not the cause of an air leak, it should have held the vacuum ideally for 24 hours or more.
2. As you have the Marina, which is fine, you can check the valve timing by direct comparision. First check the 1800 AND Marina TDC pulley marks are really corrrect (refer manometer per yesterday's post). If you are satisfied both are the same, do the valve timing check with the timing wheel.
3. As you have spent so much time it may be worth taking off the timing covers from the Marina and 1800, turning the engines until the crank and cam marks align and look for any differences.
4. You can also look at the distributor drive positions of both together. (I can't remember if you have tried the Marina distributor, cap, plugs and plug leads in the 1800? If not maybe this should be the first thing you try.)
Don't worry about the different colour of the plugs etc at this stage, if the valve timing is incorrect it would cause all kinds of issues.
One last comment (for now); I have seen comments on MGB sites that the outlet on the tappet covers is restricted to reduce the air flow on some engines, you may wish to compare the Marina and 1800 covers while you are looking at the other parts.
Regards
David
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Post by tommydp on Aug 1, 2011 8:09:00 GMT
Checked the servo now. It does not hold pressure for ten minutes, not even for 5 minutes.. I cannot hear any obvious hiss after stopping the engine, but listening carefully I believe there is a slight surging sound inside the servo. Nothing at the one way valve..
It's hard to tell, but I believe the engine runs more evenly regarding the hunt when blocking the servo. After all, we're not talking a major air leak, but I suppose it could play up at high vacuum especially. Also, blocking the servo the mixture test seemed to be more stable.
Well, the servo is about the only thing I haven't touched, and these problems have remained with various cams and even engines. I suppose I'll have to try another servo before going any further. Hope I have a good one, I believe so.. Could a potential leak here cause the cylinder one getting wet then? not sure, the outlet for the servo is close to the inlet port for cylinders one and two..
Regards, Tommy.
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Post by dave1800 on Aug 2, 2011 0:58:25 GMT
Tommy Did you ever have a look at this again to compare the Marina and 1800. It just feels as though something still isn't right. regards David Had a look at the distributor drive now. Removed it, and installed it again, as per manual. When installed correctly, it's more 1-7 o' clock than 2-8, meaning a 45 d will have to be positioned with advance pipe straight up to fire cylinder one on tdc, and match up with the cap's segment. The advance pipe usually points at the heater outlet from the cylinder head in my opinion, at least the Marina does, and I haven't touched that. So perhaps the cam is still one tooth out, then? I don't believe it, if so... I did it most accurately. After all, would it run reasonably well with the cam one tooth out, I mean there's a regular nice blow from the exhaust, though it misses sometimes.. I believe a cam out would have caused even more trouble..? Regards, Tommy |
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Post by tommydp on Aug 2, 2011 6:25:59 GMT
Tommy Did you ever have a look at this again to compare the Marina and 1800. It just feels as though something still isn't right. regards David Had a look at the distributor drive now. Removed it, and installed it again, as per manual. When installed correctly, it's more 1-7 o' clock than 2-8, meaning a 45 d will have to be positioned with advance pipe straight up to fire cylinder one on tdc, and match up with the cap's segment. The advance pipe usually points at the heater outlet from the cylinder head in my opinion, at least the Marina does, and I haven't touched that. So perhaps the cam is still one tooth out, then? I don't believe it, if so... I did it most accurately. After all, would it run reasonably well with the cam one tooth out, I mean there's a regular nice blow from the exhaust, though it misses sometimes.. I believe a cam out would have caused even more trouble..? Regards, Tommy I agree on that, Dave! It still doesn't seem right. I changed the servo yesterday, and it now holds pressure longer. It's getting the same hunting when idling still, and it hesitates. To get back to the plugs, it's just not normal the way they look. Even though the mixture now seems reasonably stable and correct, the plugs look as from weak mixture. The engine operates at normal temperature, no sign of getting too hot. To look at the bright side, the brakes got even better:-) Well, I really have to put it away for a while now, as I'm totally fed up. I guess I'll get into the timing gears again when my motivation is restored. It seems I end up in trouble when replacing timing chains, that is, not when taking out and directly putting a new one in but when installing one when crank and cam have beeen moved individually. The obviously advanced distributor drive position also points to this. Also, why on earth are cylinders 2 and 3 running leaner, than 1 and 4 when it's supposed to be the other way around? Suppose this could point to a cam timing issue. Strange that the cycle seems correct for all cylinders though, valves closed at tdc when firing etc.. It's a bit strange though, that it it actually runs as well as it does after all, if something is out. Apart from the miss and hesitation, it runs very sweetly. Looking at the timing marks with a strobe, the pulley mark still jumps some degrees, this jump follows the engine's miss/ hunting. Well, better let it, and myself; rest for a while now! Thanks all for your fabulous help so far, and please keep any replies coming, if something suddenly strike you on this strange problem:-) I really hope I'll solve this one day:-) Regards, Tommy. |
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Post by dave1800 on Aug 2, 2011 10:37:13 GMT
Hi Tommy
I can understand how fed up you are. I feel exhausted and I've not even lifted a spanner!
I think I may have the answer (a dangerous statement!) and if so it is a quick and easy job.
If yours distributor drive shaft is pointing to 1-7 o'clock as you have indicated with the engine at TDC then this would appear to be one tooth out on the drive gear. It MUST point to 2-8 o'clock. If it is in the wrong position this WILL cause misfiring.
It rotates when you insert it as it engages in the cam gears, so easy to get it slightly wrong.
I can't remember if I've posted this video link before, if I have apologies, I just think it is so clear compared with any manual and worth watching again.
regards
David
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Post by tommydp on Aug 2, 2011 12:45:05 GMT
Hi Tommy I can understand how fed up you are. I feel exhausted and I've not even lifted a spanner! I think I may have the answer (a dangerous statement!) and if so it is a quick and easy job. If yours distributor drive shaft is pointing to 1-7 o'clock as you have indicated with the engine at TDC then this would appear to be one tooth out on the drive gear. It MUST point to 2-8 o'clock. If it is in the wrong position this WILL cause misfiring. It rotates when you insert it as it engages in the cam gears, so easy to get it slightly wrong. I can't remember if I've posted this video link before, if I have apologies, I just think it is so clear compared with any manual and worth watching again. regards David Hi Dave! Thanks for the link. I've watched it before, and it's really good! I enjoy Mr John Smith's videos! Your statement is music to my ears, Dave:-) The cam, distributor gear versus crank alignment must be it some way or another. It does make sense! I agree, that the distributor gear seems to go one tooth out when installing. However, I put it in horizontally, but it seems to turn further anticlockwise before it's fully home, ending up at approx 1-7 o' clock instead of 2-8. This happens all the time, on spare blocks too.. Just can't see what I'm doing wrong.. Another interesting point, the 1800 manual says the camshaft key should be in the one o'clock position when installing the chain. Marina and Princess manuals say 2 o' clock.. The block, chain and camshafts are identical.. Why is there a difference? Well, I'm sure we have approached the problem, only trouble now is solving it:-) Regards, Tommy:-) |
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Post by tommydp on Aug 2, 2011 13:40:09 GMT
OK! Did some research on a spare block now. Using a timin chain with cam and crank wheels, which are in the same position as when it came off the engine. I put this on a spare block, adjusting the cam so it fitted, not touching the position of the chain on the wheels.
I was then able to install the distributor drive horizontally, and end up at approx 2- 8 o' clock. The dots on the wheels don't seem to line up perfectly according to my eye, but perhaps the tensioner will sort that. There's no tensioner on that block.
Well, I'm quite sure this is the issue causing the trouble. The distributor gear in the car will not settle at 2- 8 no matter how horizontally I install it:-) so the cam has to be off, suppose it could be one tooth to far advanced then.
The outcome is, I will have to get into those timing gears again and do serious research and accurate work. Perhaps lining up with the complete chain and wheels from the spares engine, and see what happens to the distributor drive then.
I whish it was a Marina now, I really hate getting that radiator out:-)
Regards, Tommy:-)
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Post by tommydp on Aug 2, 2011 19:51:39 GMT
Regarding my last reply, the chain I tried on the spareblock is single row, from a Princess engine. I never knew there was a difference, except being double and single, between simplex and duplex chains as discussed in the following link link. They claim different cam timing between the two types of chains. I've never heard of this, thinking they were directly interchangeable, but perhaps it explains the one o' clock versus two o ' clock cam key position when at TDC. I don't know. www.british-cars.org/mgb-technical-bbs/which-timing-chain-2010061422433920028.htmNot sure if this matters, I only wanted to use the single chain setup as a pattern, since it has not been out of alignment. My current engine has the duplex chain, but I'm now wondering if my current block is really from a Princess, so perhaps this must also be taken into account if it turns out the two types of chains have different timing. Regards, Tommy:-) |
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Post by dave1800 on Aug 3, 2011 0:57:49 GMT
Hi Tommy
I understand that there were (unannounced) tweaks to the cam timing over the years to shift the power curve up the rev range a little as average speeds increased with the introduction of more motorway driving. But these were only minor 2-5 degrees. You will see a similar change from some of the Mk1/11 cams changing to 5, 45 from 0,10. But nothing sufficient to throw out your distributor drive from 2-8 o'clock to 1-7.
I rebuilt a Mk3 engine which had a single chain which I replaced with a duplex and didn't encounter this or any other problem.
I wasn't aware that the Marina / Princess was differrent to the Landcrab1800 ie installing the timing chain with the cam keyway at 2 o'clock v 1 o'clock but this suggests they have the alignment dimples marked differently which could be significant if you think you may have mixed parts.
When you have the enthusiasm, I think there is no option for determining accurately TDC as previously discussed and measuring the cam timing yet again to be 100% sure the cam timing is right. The fact that the distributor drive isn't at 2-8 suggests to me that this could well be the problem.
regards
David
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Post by tommydp on Aug 3, 2011 8:11:00 GMT
Hi Tommy I understand that there were (unannounced) tweaks to the cam timing over the years to shift the power curve up the rev range a little as average speeds increased with the introduction of more motorway driving. But these were only minor 2-5 degrees. You will see a similar change from some of the Mk1/11 cams changing to 5, 45 from 0,10. But nothing sufficient to throw out your distributor drive from 2-8 o'clock to 1-7. I rebuilt a Mk3 engine which had a single chain which I replaced with a duplex and didn't encounter this or any other problem. I wasn't aware that the Marina / Princess was differrent to the Landcrab1800 ie installing the timing chain with the cam keyway at 2 o'clock v 1 o'clock but this suggests they have the alignment dimples marked differently which could be significant if you think you may have mixed parts. When you have the enthusiasm, I think there is no option for determining accurately TDC as previously discussed and measuring the cam timing yet again to be 100% sure the cam timing is right. The fact that the distributor drive isn't at 2-8 suggests to me that this could well be the problem. regards David Hi, Dave! I'll get into determining tdc and look at the valve timing after the weekend, as I'm going away for some days. What is obvious just by looking is that there's a significant difference between the rotor arm positions between the 1800 and Marina. As I've installed the distributor drive gear horizontally, I'm almost certain the cam is still out. I'll check the simplex versus duplex gears when it comes to the timing marks' positions. The simplex crank wheel has an arrow shaped mark rather than a dot, so perhaps this could be an identification mark to verify the difference. Pehaps then, If I have a Princess block I'll have to set the cam to two o' clock at tdc. Perhaps this doesn't match the cylinder head I'm using, which I'm certain is an 1800 mk 2 head.. Seems strange though, I have heard all the heads are interchangeable. I guess the timing gears are too, only the marks will be different then, obviously. There is some information on this on the MGB page, which is very tightly written, 28 pages without a single use of the shift button:-) I suppose this difference goes for the 18 V versus 18 G engines in the MGBs too. I'll have a closer look after the weekend then! I'm sure we're about to solve this now. I really don't hope I'll have to change the cylinder head again, to match the 2 o' clock position of the cam keyway. I've got a good Princess head, however it has smaller inlet valves:-( Thanks again, for lots of useful and interesting information as well as your fabulous help:-) I would be completely lost on this without it. Regards, Tommy:-) |
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Post by dave1800 on Aug 3, 2011 8:38:51 GMT
Hi Tommy
I'm off for a few days too so just a quick comment. I can't see it is can be anything to do with the head, this isn't an OHC engine so the head just sits there with the valves operated by the push rods. Nothing you do to the head can do anything to the camshaft / valve timing, only the valve lift if it is skimmed or the rockers modified.
If you have a Princess block does it have the "scallops" to give clearance to the inlet valves. I seem to recall that the Princess 1800 reverted to the smaller inlet valves from the Mk1 1800.
Given the uncertainty I think you just need to deal with this as though you had a crank, pulley and camshaft with NO dimples or timing marks just as you would building a modified engine.
Then:
find the precise TDC, mark the crankshaft pulley
fit the timing chain with the crank at TDC (no1 as usual), turn the cam so that the distributor drive sits at 2-8 with the cam at its correct position for no 1 cylinder
check the valve timing
Bingo!
It may be that with your components that the dimples etc may not line up, only matched items will.
Enjoy your break!
regards
David
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Post by tommydp on Aug 3, 2011 8:55:30 GMT
I'll do exactly as you say when I return:-)
Yes, the Princess has the same inlet valves as the mk 1 1800, there are "cutaways" for the valves on the block however. I suppose they are big enough. I guess I would have noticed if there was an issue here, valves crashing into the block etc? I hope so.
So long, have a nice weekend and a safe journey:-)
Regards, Tommy:-)
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Post by dave1800 on Aug 7, 2011 8:51:26 GMT
Hi Tommy Hope you enjoyed your break. It's been very wet (ie big floods) here so I have returned a day early. Here is a link showing the small changes in cam timing to the MGB when they changed from duplex to single timing chains, see the picture about 1/4 the way down the file showing the keyway changes - it is quite probable that the Crab 1800 followed a similar change. The bottom line is that whether you use the duplex or single arrangement it will make only a marginal difference and not be the cause of your problems. www.1977mgbsupercharger.com/restoration/default.htmlHope you are all fired up again! good luck David |
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