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Post by tommydp on Apr 12, 2011 8:32:48 GMT
Thanks, David:-) I'll have a look at the timing againg later this evening. Suppose I'll try to look at the pushrod side of the cylinder head then, in stead of the valve end. You would perhaps be able to verify the spot more exactly by judging how pushrod rotates..
Anyway, the cam will have to be changed then. I see Earlpart.co.uk offer cams for both S and standard 1800. Reprofiled, though.. Anyone had experience with these?
A Norwegian MG specialist offer standard MGB cams. However, I'm not sure of the quality of this item.. Something from the far East I guess.
OR, dismantle a spare block and if not too worn out, use the standard cam from that..
I see no reason why I shouldn't be able to change the cam with engine in place, cutting away a bit of the radiator air panel on inner wing.
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Post by tommydp on Apr 11, 2011 21:59:21 GMT
I'm getting there now!
Cam and crank weels and chain are mounted correctly. Marks on the wheels are correct, compared to other wheels. Marks line up correctly.
Printed out and installed a timing disc, using a piece of wire as a steady reference point. A bit hard to establish the spot on, exact top dead centre, but believe I have been as accurate as possible. Even though, if possibly a few degrees out, the readings confirm that the camshaft itself, in my opinion, HAS to be the cause of all these headaches:
This is definitely not a standard 1800 cam, AND I'm not sure it's a standard MGB/ S / Marina TC either!
I just can't believe the results, and I just can't see that I've measured incorrectly. I practised on the old block yesterday:-)
Well, I adjusted valve clearance to 0,020 on cylinder one inlet and exhaust valves, and timing found is:
Inlet opens at 21 degrees before top dead centre Inlet closes at 88 degrees after bottom dead centre, if this is the point where valve is fully closed, that is the spot where you have clearance between rocker and valve stem? Or is it when it's starting to close? If so, This measure is incorrect, of course
Exhaust opens at 56 degrees before bottom dead centre Exhaust closes at 38 degrees after top dead centre, when there's clearance rocker to valve stem.. as for inlet
What on earth is this? I believe i can read the numer 285 at end of camshaft. I've googled and foud this to be a hot MGB cam. Specs don't really match though.. Guess I must have got it wrong. I'll have another go tomorrow..
So what to do then? This cam will have to come out anyway, I guess!
Regards, Tommy!
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Post by tommydp on Apr 11, 2011 10:23:27 GMT
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Post by tommydp on Apr 11, 2011 9:46:57 GMT
I'm really excited about checking the valve timing this evening:-) I would expect it to have the "16-56-51-21 "S, MGB, TC specification, but who knows?
Unfortunately, My Marina is a single carb.. Guess I have to see if I can fit everything so the valves will follow opening and closing at 16-56-51-21 then.
Could they have fitted a cam meant to opening inlet valve even earlier than 16 degrees, so fitting and current early opening is correct after all? Would this then be a "hotter" MGB cam? If so, they'd better prepare for changing that cam, even if they have to stand outside their workshop doing it:-)
Well, I'll confirm the valve timing first:-)
Regards, Tommy:-)
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Post by tommydp on Apr 10, 2011 21:09:54 GMT
I've now had a thorough look at a spare 1800 block, to learn and understand the opening and closing of the valves. I watched the tappets' movements and estimated degrees of opening and closing according to btdc, abdc, bbdc and atdc:-) No doubt, that block had the standard cam, 5-45-40-10 and cam and crank corresponded correctly:-)
Have not removed radiator etc yet, but had a more thorough look at the troublesome new engine's timing for number one inlet valve. Mark on pulley is correct for top dead centre, no doubt. However, there's no doubt that number one inlet valve opens to early. Estimating from the 5-10-15 graduation on timing cover, I would say it opens at about 25 degrees btdc.
It will be really interesting to investigate the rest of the valve cycle, to see if it corresponds to a 16-56-51-21 cam wrongly installed- perhaps due to a misplaced mark/ marks on the cam and/ or crank wheels! According to my brilliant old "British Leyland Norge" (Norway) Technical data book, covering all BL cars: all MGBs, Marina TC and 1800 S had the 16-56-51-21 cam
I'm optimistic! One can't give up:-) .... but believe me, if this wasn't my late grandparents' car from new... it would be long gone:-)
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Post by tommydp on Apr 10, 2011 18:59:14 GMT
Do you think we're getting there, David? I have a good feeling, and we've certainly done progress.
I was perhaps somewhat unclear about it being fine for ten minutes. The idle is bad and misfiring occurs both cold and hot. It seems however to perform worse after driving for a while. Comparing to the Marina, I'm sure the 1800's advance vacuum suffers as I have to open the throttle too much to make it idle at all. There's vacuum at advance pipe at idle on the 1800, not the Marina. I guess I have to compensate for whatever the problem is, by turning the throttle up.
It's amazing how the Marina's running is lighter, effortless and smooth. Far more responsive when revving too, a healthy revving sound. I will try switching coils tomorrow.
Well, I guess it's out with the radiator and off with the timing cover then?
Will I be able to verify the opening and closing of the valves by making and using a circular scale with angles/ degrees on, perhaps? At least it will give some ideas.
Am I right if the valve timing is the instant the rocker contacts the valve stem? And the timing is the amount of degrees before or after TDC at this very moment? Valve clearance should be 0.020 when doing this? Is it then correct to use the "rule of nine"?
Example: to check valve timing for valve one, turn engine until valve 8 fully open. Adjust clearance on valve one to 0.020. Turn engine until valve one rocker contacts valve stem. Check timing/ degrees.
Sorrry about all questions, I feel really bad about them.. Hopefully, this post also comes handy to others, though:-)
Tommy.
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Post by tommydp on Apr 10, 2011 11:46:35 GMT
Vacuum gauge tried out, plugged in on manifold.
At slow idle, it's flickering lightly at about 10 inHg, at slightly higher idle it shows same flicker at about 11- 12 or so.
Revving engine: drobs to zero, up to about 20, back to 10- 11.
Well, valve timing issue, then? There is no air leak, I assure you.
At least, finally some proof to the problem to look at the bright side. What a marvellous instrument, the vacuum gauge! I've never used one. I'll install one in the crab once finished, for sure.
Thanks for guiding me to use of this, Dave, as well as the sites showing the different readings. Your help is fabulous! I'm very thankful!
Tommy.
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Post by tommydp on Apr 10, 2011 10:36:30 GMT
By the way, Backlash on the ultra low mileage, sweet running Marina is approximately same as the Crab..
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Post by tommydp on Apr 10, 2011 10:35:00 GMT
Checked valve lift now, on all valves. Believe I have done it correctly..
I've tried to be as accurate as possible, measuring pushrod movement from valve fully closed to fully open. It seems all valves have the same lift at least, however these are no scientific measures:-) All in all, the movement seems to be 7 mm (about 0,28 inches) on all valves. Don't know how accurate this will have to be.
Am I correct if the lift should be 0.34 inches? Well, what does this mean?
Tommy.
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Post by tommydp on Apr 9, 2011 7:47:45 GMT
Some progress, don't have much time working on it today but checking out everytime I'm out having a smoke:-)
There seems to be backlash in the engine. Turn engine in the right direction, then the other way around and can feel quite a lot of backlash, at least 5 degrees I would say. Rotor arm remains accordingly before going backwards. How much backlash can be tolerated?
Guess it boils down to the tensioner then. However I checked it's operation, prior to putting the cylinder head on though. I've seen before that a tensioner will go back into its housing a bit, taking up slack at the moment the engine is turned backwards, likewise go out again, taking up slack when turned in correct direction. That is, the crank moves at this moment, not the cam. Is this acceptable? What makes a new tensioner do this, on a new chain? I know how to install the tensioner, releasing it etc or at least I think so:-) I also assumed they had mounted it correctly, as I could see no slack/ backlash when I got it back.
Tensioner, cam and crank wheel and timing chain are new of course.
Well could this be something, if so what to do? Should there be any backlash at all on a new engine?
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Post by tommydp on Apr 9, 2011 6:33:34 GMT
Timing scatter appears both with and without vacuum pipe. I've tried different distributor caps, trying the Marina coil later.
When it comes to petrol consumption, I'm thinking of the total driving since installing the engine last weekend. I'm not too worried about that, though. Guess it will be ok when everything is sorted.
Exhaust pressure: I'm thinking of the blow you feel when you hold your hand at the exhaust pipe end. On earlier 1800s I remember a quiet, rythmic mild blow here at idle. This one has a steady powerful blow. A bit hard to explain, and language doesn't make it easier:-)
Cylinder head: valves have ben ground. Don't suspect the head, really. Came off the previous engine, wich at least idled fairly well even though I had similiar trouble on that one too in the beginning..
I have blown the tank vent pipe several times. Appears to be fine. There's never a vacuum when opening the tank filler cap.
Well, hope to be able to do some work this weekend. Updates will come:-)
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Post by tommydp on Apr 8, 2011 20:56:10 GMT
I'm very surprised that you can see the timing varying. "Off the wall" thought - they have put the chain tensioner back on, haven't they? Chris. They have. Engine delivered and returned without timing cover, so saw it myself and checked it as I put the cover on.
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Post by tommydp on Apr 8, 2011 20:30:39 GMT
Well, finally got the mixture right. Works as it should with the lifting pin. Didn't have the time to check petrol height in jet. Idle still lumpy but more steady. However it will suddenly stall for a while, then suddenly catch up, rise and idle more smoothly. after revving it will stall and catch up again. After a short time parking it will idle even worse for a while. Still lots of pressure at the exhaust pipe and occasional spitting.
Took it for a drive. Fabulous performance during first 10 minutes or so. (Engine at normal temperature when starting driving, been standing at idle for a while.)Then it starts cutting out when driving and performance is down, idle worse again. Fuel consumption seems to be horrible, by the way. All this reminds me of the previous engine. Had a look at the plugs after the drive. A bit on the rich side, but they are almost identical. Cylinder 2 and 3 a tiny bit richer, it seems. By the way, it starts instantly. Cold or hot.
Had a look at the timing marks with a strobe timing lamp. Unfortunately I don't have a tachometer at present, so doesn't tell that much. Timing mark did not appear steady, though. Fluctuating about 5 degrees, seemed to match the misfire.
Hopefully, I'll get some time to investigate further tomorrow. I'm also getting a vacuum gauge.
Regards, "Desperate Tommy"
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Post by tommydp on Apr 8, 2011 9:35:14 GMT
Two stupid questions. What is the code of the SU needle you are using? If you remove the piston and needle assembly how far down the jet is the fuel (after the engine has run). I'm using the ZH needle, which is stated as standard. Seems to be centralized fine, falls with a nice click with adjusting nut fully up and down. I'm not sure about the height of fuel in the jet right now. How can I find out? Interesting... Perhaps we are getting somewhere. I can't help tinking it's mixture related. Sorry I haven't replied to your latest post, I just didn't get the chance to work on it yesterday.. Other things need to be done as well, as cleaning the house for the weekend etc... lol..
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Post by tommydp on Apr 7, 2011 10:09:33 GMT
I'll get a vacuum gauge today! It can surely be helpful. Will also try to measure valve lift and check all valve operations again.
I've tried 45 d with 50 degr dwell as well as 25 d with 60. Also tried the dizzy from the sweet running Marina.
What made me switch to newer oil separator was that oil appeared in the diaphragm valve on the previous engine, learning from various MGB articles the newer one was better than the "Popeye- pipe" type, when it came to letting oil into the combustion. I believed the oil fouling of the plugs came as a result of the breather valve letting oil in.
However, judging by the oil fume smell from the exhaust when breather attached, even on the new engine, it seems to me there's to much suction into the engine in some way. As said, my palm is almost stuck at the oil filler pipe at idle, when breather attached, even at slow idle. Fuel consumption has also been on the thirsty side no matter what mixture setting.
On the bright side, I now know the whereabouts of a set of twin HS 4 carbs for a Marina TC if that turns out to be the way to go:-)
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