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Post by tommydp on Aug 13, 2011 22:39:43 GMT
I've been following this with some fascination; Dave and Tommy seem to have the patience of saints. Not sure that I can add anything on the purely technical level, but the following observation springs to mind. It's a tuned engine and logically there would only be one issue to cause poor running. As Tommy seems to have a limitless supply of parts (You lucky chap  ), I would suggest stepping back and getting the engine back to "standard" tune as nearly as possible. Standard cam, standard head, etc. From there, change one component at a time and see what happens. If it's fine, swap it back out again and fit the next component until it starts playing up. It's a process of elimination. I suppose it is possible to just push the tuning too far and she just won't have it - apparently this is a common problem for VW "boy racers" - I do hope not. Duplex chain is the same as the "A" series engine and is as cheap as chips, so don't mess about, buy a new one. Fingers crossed for you, Chris. Thank you, Chris! I'm glad you are enjoying this thread. Dave is the true saint here! His patience, knowledge and efforts to guide me through this is amazing and sincerely appreciated by myself! Dave is really a hero! These posts are almost turning into a workshop manual on their own, so hopefully others benefit from our headaches as well! Regarding the engine, it's back to original specs now, except the overbore of course. Standard cam, head etc. I suppose the timing is the issue, as the only times I've had trouble with these engines is after messing with the timing gears. Also, being a mix of different parts, sorting the engine is a challenge. Anyway, I'm now certain the block is a Princess 1800, after doing some research on the engine number. It does indeed have cutout for valves though, so does two other Princess blocks I have. perhaps it was done anyway, in case they were to be used as exhange blocks for an 1800? I don't find it obvious though that a princess block would need a Princess cam and head rather than an 1800 cam and head. The blocks appear identical to me. Anyway, I've started from scratch again, investigating sprockets and chains as suggested by Dave. Put crank at exact tdc, by rod tool into cylinder method and finding the middle, and aligned crank and cam sprockets by marks, turning cam, without chain. Then put chain on sprockets, marks and sprockets' centres still in line, and mounted timing gears to engine. They went right on the keyways. Comparing to John Twist's video, distributor drive seems very identical. I'll now check valve timing again tomorrow. Activating tensioner, The marks and sprocket centres seem to keep in line at tdc, however at tdc when marks are closest to eachother, the cam mark seems a tiny bit retarded to my eye. At tdc when marks furthest away from eachother they are perfectly lined up through centres of sprockets too. Perhaps I'm being over picky.. I'll try to post some pics of the timing gears and distributor drive tomorrow. Regards, "Tommy the cam timer":-) |
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Post by dave1800 on Aug 14, 2011 8:42:11 GMT
Tommy
You posted earlier that " ... The rocker shaft is new. It's from a MGB supplier, however the part number of the shaft was same as 1800. The rockers have a different number though.. "
Other than checking for wear I have never replaced a rocker shaft. But looking at MGB sites (aren't they a wonderful source!) there seem to be a number of important issues.
(a) the oil way for the rocker shaft through the pedestal was changed somewhere along the line, there seems confusion as to when, so that the later oil feed holes are offset and won't match the earlier blocks, if I am reading the posts correctly. Your engine is a mix of parts so there could be a problem.
(b) when fitting new rocker shafts and rockers there are discussions about the need to drill oilways and ream the rockers
If your rockers and valve gear are not getting the proper oil supply, I think you would have noticed by now, but certainly worth checking once you have the valve timing correct it could cause all kinds of problems as you can immagine.
I have noticed that while you can lay a straight edge across the timing dimples and the centre of the crank and cam with the cam dimple at 1 o'clock, when you rotate them 180 degrees so the two dimples are opposite each other they may not line up absolutely perfectly, but they won't be far out. It depends on the stretch in the chain if everything else is OK. As Chris has suggested a new chain is so cheap why not get one?
Sorry to throw another issue at you, but better than saying nothing!
regards
David
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Post by tommydp on Aug 14, 2011 8:58:30 GMT
Hi Dave!
Rocker shaft has the correct direct oil feed, not offset as for later engines/ heads, so would be ok. Not sure if the rockers may have a different ratio though, as they have a different part number.
Indeed, I should get a new chain. However, the chain was new when engine was put together in April, so should be OK I suppose. And of course, I want to put this together today and not wait for a new chain to arrive:-) We'll see, perhaps I'd rather wait for a new one after all.
Regards, Tommy.
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Post by tommydp on Aug 14, 2011 16:43:54 GMT
Perhaps a dangerous statement, but I believe I've finally solved it. It's really starting to make sense, and if I'm right it explains earlier problems too.
First of all, with my tools and equipment, I am not able to determine the exact timing of the cam by watching the pushrods alone. Although I seemed to find the correct reading this way some days ago. Therefore, I have to rely on the 0,020 clearance method checking timing when pushrod can be rotated and not. After all I managed to get exact reading on the Marina this way.
Well, I'm now back to the 1800 cam, 1800 head is still on, rocker assembly is the new MGB one, which I'm certain is identical to the 1800's.
I still couldn't get the correct reading. As I have to rely on the rocker/ pushrod method the cam followers/ pusrods came to my mind. I've been using the later bucket followers and the corresponding longer pushrods all the time, believing they were interchangable. This assembly, which is used on the Princess, as well as later MGBs and Marinas are more than 3 mm shorter than the earlier follower/ pushrod assembly, used on mk1 and mk2 1800s.( Not sure about mk3). Wouldn't this make some difference in the valve operation by the pushrod/ rocker, as I'll have to screw the rocker adjuster screw 3 mm further down on this bucket follower assembly, than on the older follower assembly? These thoughts started it.
I installed the older type followers and pushrods on cylinder one, inlet and exhaust. Timing gears still in the same position, as they line up well and drive gear position seems fine. Now I adjusted the clearance to 0.020 and BANG! 5-45-40-10. Spot on! (OK, the inlet close is perhaps 47-48, but I suppose that's good enough?)
So, is the moral of the story that the pushrod/ followers, camshaft and rocker assembly can't be mixed between Princess and 1800 engines. (The rocker assy is obvious as the Princess has offset oilway..) I'm not sure, but this is the first thing in months to make sense:-)
Regards, Tommy.
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Post by dave1800 on Aug 15, 2011 1:13:17 GMT
Hi Tommy
This is most odd! Are you 100% certain that the later, shorter tappets are not sticking? You could try pushing down on the pushrod as the valve closes to check this to see if it disengages 10 degrees sooner. If you think about it, you are setting a gap of 0.020" to allow for the cam measurement to be taken before it actuates the rocker. It shouldn't matter what tappets or pushrods you use, a wooden stick with a flat base would suffice! The rocker adjusting screw won't affect the measurement.
If it's not the tappets sticking then I don't know what else to suggest as the cause, but you may be happier to use the longer tappets and shorter pushrods as you are getting the correct cam profile reading and put it back together. You should either use those tappets and pushrods that were with the camshaft you now have fitted if they are in good condition, keeping them in the same order ie no1 inlet tappet and pushrod etc, or fit new ones.
Nearly there I think (a dangerous statement!)
regards
David
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Post by threelitre on Aug 17, 2011 14:28:39 GMT
Oh my - I'm on a holiday and this thread has increased by 3 more pages...
But I am lost with these details of the engine, as I have not yet torn one apart - and from reading manuals not all of your findings (and Dave's knowledge) would be able to find an explanation. The thought of something sticking seems quite logical to me. Has it got single valve springs? I found the single valve springs on one of our A-series so weak that I at first had trouble to adjust the clearance because I was used to the stiff springs on my Maestro's A+. With such weak springs some stick-slip effects might keep the valves from operating correctly.
Regards,
Alexander
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Post by tommydp on Aug 17, 2011 21:44:41 GMT
Indeed, these threads have become massive:-) Car has mk 2 head with double valve springs. I can't see what's sticking, as I've tried 2 different heads and two sets of followers.
Anyway, I've done some progress, but I don't dare saying I've solved it. Then the damn thing will probably start missing on my way to work tomorrow:-)
However it's getting better by the day.. I believe I've been highly unlucky with different issues playing up as well as the mix of parts has been a big challenge.
Things I've looked into and found out recently: Reconditioned carb had a too strong chamber spring. A lot longer than the other yellow springs I have. Repro Chinese distributors are crap and waste of money. I'm wondering if there's a difference between distributor drive gears for 1800 and Princess/ Marina. The part numbers are at least different. If so, I've been mixing up here too..
Cam timing is now correct. I'm wondering if there was to much slack in the previous chain. At least now the tensioner doesn't move as much in and out when turning engine by hand. Chain felt much tighter when installed.
The latest improvement, which made a very noticeable difference both idling and running, included putting in a Lucas 45 d dizzy and setting it visually as the Marina's, advance pipe pointing to lower bolt of heater outlet on cylinder head. Have not looked at the timing at all:-) Slightest pinking in 4th up a very steep hill at 60 kmh, so will retard it a bit.
Fingers crossed:-)
Regards, Tommy
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Post by dave1800 on Aug 18, 2011 1:39:09 GMT
Hi Tommy
Sounds like good news at last! Just one word of warning though, set the ignition timing with the timing light before you cause any damage. Over advanced timing is probably the biggest engine killer. It's probably not too far out, but it just could be.
Hook up the vacuum guage sometime again and let us know how it has changed.
I think we have all learned lots of lessons here and the need to be careful sourcing key components like carbs and distributors. A few pounds, kroners or dollars saved now could translate into big costs down the line.
A fun way to have spent your summer holidays!
regards
David
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Post by dave1800 on Aug 18, 2011 7:08:03 GMT
Hi Alexander This certainly had me baffled as it turned out Tommy had a new rocker shaft and the tappets and push rods changed to those from a Mk111 engine (or Princess or Marina) with shorter tappets and longer pushrods. My thinking is if the valves/ guides or valve springs had been sticking the point when the pushrod disengaged could have been earlier, whereas Tommy was getting a longer opening. On the other hand, if the rocker was sticking on the shaft this could stick in any position, but if the new tappets were sticking slightly they could hold the push rod in contact with the rocker for longer . (Both types of tappet are supposed to be the same diameter and interchangeable together with the appropriate pushrod). That's why I suggested he pushed down on the pushrods as the valves closed and he took the cam readings. I agree that the Mk1/11 set up with double valve springs and duplex timing chain is certainly preferable. Did you see (Penguin) Chris' fuel consumption of 36+MPG on a long journey fully laden by the way. A bit better than yours! Regards David The thought of something sticking seems quite logical to me. Has it got single valve springs? I found the single valve springs on one of our A-series so weak that I at first had trouble to adjust the clearance because I was used to the stiff springs on my Maestro's A+. With such weak springs some stick-slip effects might keep the valves from operating correctly. Regards, Alexander |
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Post by threelitre on Aug 18, 2011 8:48:32 GMT
Did you see (Penguin) Chris' fuel consumption of 36+MPG on a long journey fully laden by the way. A bit better than yours! Very impressive indeed! I know that while traveling the UK I always get lower (=better) consumption figures than here on the continent. But I was very happy for the 1800S (fully standard) to get any more than 31.4mpg. The Maxi can better 36 with not too much trouble - and don't ask about the 3litre  I just returned from my hols and our fully laden Rover Tourer with 1.6 K-series managed a bit more than 40.5mpg whilst averaging exactly 63mph with A/C on over a distance of 700 miles. There has been some progress over the years! Regards, Alexander |
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Post by tommydp on Aug 19, 2011 6:05:31 GMT
Well, as I said, I was not certain it was ok yet:-) And yesterday the trouble was back of course. I retarded the timing slightly to overcome the pinking. It's now 12 at 600 rpm. It's exactly as earlier, misses at steady speed and hunts at idle. What still get's me is that nr 1 and 4 piston still appear wet, even after a long drive. I suppose it'll have to be oil then. There is some smoke after rolling downhill with throttle closed. Perhaps the valve guides are too worn, letting unmetered air in. The idle will fall when I spray some "easy start" into the oil filler hole. Strange I have this problem on 2 cylinder heads though.. Cylinders number 2 and 3 are dry soothy.
Well, I suppose I'll just have to put it away now. This car really remains a mystery and I'm totally lost and fed up. I suppose we have been through all possible causes now, so don't expect anyone to follow up this thread further. Thanks for all your help:-)
Regards, Tommy:-)
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Post by dave1800 on Aug 19, 2011 7:53:27 GMT
Hi Tommy Sorry to hear it's still not sorted. Did you change back to the longer tappets and shorter pushrods? If not, and if the shorter tappets are sticking and the cause of your odd cam profile readings then this could cause serious engine damage to the camshaft, the tappets and potentially the valves and pistons. The tappets should have sufficient clearance so that they can rotate freely. Regards David Well, I suppose I'll just have to put it away now. This car really remains a mystery and I'm totally lost and fed up. I suppose we have been through all possible causes now, so don't expect anyone to follow up this thread further. Thanks for all your help:-) Regards, Tommy:-) |
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Post by tommydp on Aug 19, 2011 8:36:45 GMT
Hi Dave! I changed to longer tappets and shorter pushrods. No one of the tappets stick as far as I can see. The bucket type ones, which were installed earlier were unmarked and rotated freely too. The cam lobes are totally unmarked. No wear through the outer, hard layer.
The fact that the piston tops don't get soothy on cylinders one and four amazes me. So something is seriously wrong with the combustion I guess..
Regards, Tommy:-)
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Post by dave1800 on Aug 19, 2011 10:04:29 GMT
Hi Tommy
Do you have a friendly garage that has an ignition analyser, ie like the old "Sun" machines, basically just a scope with 4 channels to see what is going on in the primary and secondary circuits while the engine is running throughout it's rev range. It would only take a couple of minutes to hook up. Maybe your Physics dept at your school (you are a techer I believe) has the equipment? At least you could rule in or rule out an electrical / ignition problem.
Without reiterating too much, I have had totally (I mean totally) clapped out engines that would idle and not misfire.
regards
David
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Post by threelitre on Aug 19, 2011 11:42:53 GMT
Without reiterating too much, I have had totally (I mean totally) clapped out engines that would idle and not misfire. Yepp, same here. Even with a fully worn carb spindle they can be made to run smooth with ease (as long as it's a single carb). Tommy, which parts did you NOT change over the last weeks? Regards, Alexander |
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), I would suggest stepping back and getting the engine back to "standard" tune as nearly as possible. Standard cam, standard head, etc. From there, change one component at a time and see what happens. If it's fine, swap it back out again and fit the next component until it starts playing up. It's a process of elimination.
