Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: hey_kramer on Thursday,March 06, 2014, 11:04:32 AM
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HELLO ALL and thanks for looking at my first post!
I recently inherited my father's '73 TCS and it hadn't been serviced...at all...in over 20 years. I disassembled the engine and gave everything a good workover, installed replacement parts/gaskets, etc., but in my EXCITEMENT to tinker, like a FOOL in a hurry I didn't mark any of the camshaft timing. I've never timed camshafts before so I have some rudimentary questions that I could not answer by looking in the workshop manual or in the forum.
To begin, I've reinstalled the camshafts but the sprockets are not installed yet. I've got the #1 piston at 5 degrees BTDC, as I have Zenith carbs.
1) Each camshaft sprocket has 3 circular holes through it, for what I call the camshaft's "nub" to fit into. I kept track of which sprocket goes with which cam, but which of the 3 holes do I use for the nub?
2) Once the sprockets are correctly situated, should I rotate each cam (NO timing chain installed yet) so that the sprocket timing marks are next to each other and horizontal with the cam cover mounting face, as according to the manual?
3) When timing, is 5 degrees BTDC best or do you guys who have Zeniths like to use something different than the factory setting?
BIG THANKS!
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Don't mix up camshaft timing with Ignition timing. Set the camshafts with No 1 at TDC.
Have you read the Workshop Manual? If you had, you'd know the "nub" is called a dowel. The dowels point outward, if I remember correctly, when the engine is at TDC. That will tell you which hole to use, though I can't remember being confused. There are three holes, but only one, the middle one, is the same size as the dowel.
The exhaust sprocket should have EX etched onto it.
If you don't have a workshop manual, look here: http://www.lotus-europa.com/manuals/tcwork/e/index.htm
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Thanks Roger! I own an original binder of the workshop manual, but I never put 2 and 2 together to realize those nubs were called dowels! Thanks for that. The camshaft/sprocket illustration has the dowels pointing outward but it was unclear if that illustration correlated to TDC. So, taking your advice into account I will:
1) Set #1 to exactly TDC,
2) Fit the camshaft dowels to their exact-size sprocket hole (probably middle), ensuring the EX sprocket is on the exhaust cam,
3) Like the manual says, rotate the shafts until the sprocket timing marks are next to each other and horizontal to the cover mounting face,
4) Connect timing chain and tighten,
5) Crank #1 to 5 degrees BTDC and install ignition components (distributor, plugs, etc),
6) Put cam cover on and hope it starts
7) Fine tune distributor timing
Anything else?
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Thanks Roger! I own an original binder of the workshop manual, but I never put 2 and 2 together to realize those nubs were called dowels! Thanks for that. The camshaft/sprocket illustration has the dowels pointing outward but it was unclear if that illustration correlated to TDC. So, taking your advice into account I will:
1) Set #1 to exactly TDC,
2) Fit the camshaft dowels to their exact-size sprocket hole (probably middle), ensuring the EX sprocket is on the exhaust cam,
3) Like the manual says, rotate the shafts until the sprocket timing marks are next to each other and horizontal to the cover mounting face,
4) Connect timing chain and tighten,
5) Crank #1 to 5 degrees BTDC and install ignition components (distributor, plugs, etc),
6) Put cam cover on and hope it starts
7) Fine tune distributor timing
Anything else?
That pretty much sums it up, Mr Kramer. In step 2 it is indeed the middle hole you are looking for. I wouldn't get too hung up on step 5. 5 degrees is easily covered with distributor rotation once installed. Just be sure you have some rotational freedom in the distributor to the advance direction. Are you running Stromberg carbs? You will likely find that the engine wants more than 5 degrees advance. You will probably be in the 10 degree range to make the engine happy, perhaps more. When my engine is timed at 5 degrees it is quite lazy. The Miles Wilkins book also recommends more then 5 degrees. By the way, if you are going to be playing with a Twin Cam, I recommend the Miles Wilkins book. Lots of good information there and it has recently been reissued in soft cover. Good luck.
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YOU NEED TO GET THE CAMS IN THE RIGHT POSITION EITHER BEFORE THE HEAD GOES ON, OR, BEFORE YOU FULLY TIGHTEN THE CAM BEARING CAPS !!
It is very easy to bend a valve otherwise.
I set piston #1 to TDC then I turn the crank back 90° so that NO piston is TDC, then I place the head on with the cams in the proper position for #1 TDC. Finally I turn the crank ahead 90° to bring piston #1 back to TDC.
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:I-agree:
Excellent advice. I also managed to break a camshaft many years ago during a rebuild (my only brain cell was on holiday) so be very careful. It's not a difficult task, but there are places where a lapse of attention will make it very upsetting.
Also the recommendation for Miles Wilkins book is a good one. It has more detail than the workshop manual and has been written later, thus benefiting from knowledge gained after these engines had been in service for a long time. In some areas he disagrees with the OEM manual (timing IIRC ?) so it's good to have background info from other sources if you find problems after setting up as per the Lotus manual.
Brian
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Everything is back together and cranking smoothly...but now I have extremely weak spark / no spark. That really put a damper on my mood at 2:30AM when I turned the key. >:( It wouldn't fire up and I diagnosed it as the plugs not getting any juice. I suspect my Ignitor II air gap is too big again. Will further investigate after work.
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YOU NEED TO GET THE CAMS IN THE RIGHT POSITION EITHER BEFORE THE HEAD GOES ON, OR, BEFORE YOU FULLY TIGHTEN THE CAM BEARING CAPS !!
It is very easy to bend a valve otherwise.
I set piston #1 to TDC then I turn the crank back 90° so that NO piston is TDC, then I place the head on with the cams in the proper position for #1 TDC. Finally I turn the crank ahead 90° to bring piston #1 back to TDC.
Yes indeed. Excellent catch Mr Collier. This is most critical information.
Also, Brian's mention of cam breakage is something to keep in mind. Cam bearing caps should be tightened carefully and incrementally. Don't just wing one down all the way then move on to the next, but ease them all down a bit at a time whilst being wary of anything 'not right'.
Though perhaps too late now, I should have mentioned that it may be prudent to apply cam lube to the lobes. This may not be necessary for existing parts that are already worked in to each other, but it's a prudent step nonetheless, and one I always observe whenever I have a cam out of an engine.
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Hello, Welcome! I also inherited my father's TCS. He bought it new in 1973, when I was 5 years old. As yours, mine had been stored for about 20 years when I towed it home and started sorting it.
I can't offer any help on your cam, but you've already sorted it anyway.
Cheers,
Mark
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Thanks everyone for all the cautionary tips. I'm DELIGHTED to report that the engine runs! Weak spark was from the IGNITOR II ignition module air gap being too wide. :headbanger: BUT frustrated to say that the timing is quite terrible. It won't run faster than about 400 rpm with full throttle, and dies as soon as I stop giving it gas. I timed it just as we agreed to in the earlier posts:
Ensured the EX sprocket was on the exhaust cam;
Used the middle hole on each cam sprocket;
Put #1 to TDC (Double-checked by actually making SURE that it was TDC, not just assuming it was by only looking at the flywheel timing mark);
Rotated each camshaft so that the sprocket timing marks were exactly next to each other and horizontal with the cover mounting surface;
Installed the timing chain and tightened, checking that the sprocket timing marks were still aligned afterwards;
Rotated to 10 degrees BTDC and installed distributor (10 degrees because it seems to be the modern suggestion instead of 5);
I played with the distributor timing by rotating it but it has no noticeable effect. The car ran REALLY well 2 months ago (before the teardown) with it at 5 BTDC, so I put it back to that, but same sputtering and dying results as it did at 10.
The owner of the car, before my father, raced it professionally. Perhaps he installed some altered engine components which require timing that is quite different from stock, which are preventing it from running smoothly. I still suspect the camshafts/sprockets are to blame. Perhaps it is not the middle holes on the sprockets? It's not the carbs either. They were recently rebuilt and were working fine before the teardown.
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How far did you have to rotate the cams to line them up?
Do a compression test.
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It sounds as if you've got the cams right, IIRC the two marks on mine don't line up exactly but it's a while since I last did that job so memory is hazy.
I think I'd look at the distributor again, mainly because it's the easiest thing to check and cross off the list.
I set the flywheel to TDC to install the distributor. Position the pigtail connector towards the block with the rotor arm pointing towards the rear distributor clip such that it rotates towards #1 as the screw meshes. Then I turn the flywheel to the timing mark and adjust the distributor/ignition timing roughly by using a bulb across the distributor/coil connection and earth. Once it's about right I start up and put a timing light on it to get a better setting.
In the past I've managed quite successfully to get this wrong by not having the rotor in exactly the right position before installation and although the engine will run, it's not what you'd call good. ::)
For some reason I can't find the section in my Europa Manual (and it's a proper, paid for, genuine Lotus one ! ) so I have copied the relevant page from the Elan manual into a JPG and attached it to this post just in case you have the same issue.
Brian
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Are the cams in the TCS (Federal) supposed to have any overlap in timing? By overlap I mean the exhaust valve and intake valve on any given chamber are partially open at the same time. My coworker who races professionally suggested I find that out. THANKS!
***Update***
So upon further research I see that under the factory specs there is a 132 degree overlap of the valves. This cannot be right, can it? Surely I've calculated something wrong here:
Exhaust opens @ 66 BBDC (114 degrees clockwise after TDC)
Inlet closes @ 66 ABDC (246 degrees clockwise after TDC)
246 - 114 = 132 degrees of everlap. :blowup: Really that much????
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There's a page here with a diagram very similar to the one in Miles Wilkins' book that tends to support a similar overlap theory. The text is about any engine, but the diagram at the bottom of the page is from the TC motor, and a picture/sketch makes it much easier for me to visualise what's happening with the valves rather than working with a list of numbers.
http://gglotus.org/ggtech/907camdial/body-907cams.htm (http://gglotus.org/ggtech/907camdial/body-907cams.htm)
If the cam timing interests you, then I'd suggest you grab a copy of Mile's book before it goes out of print again. There are sections on setting up standard cams and also how to approach timing with non-standard cams and cylinder head thicknesses, plus what you can expect from them.
But does it matter? You can't change the profile, only the cam and ignition timing so it doesn't really make any difference what the overlap is, does it ? I guess I'm saying "don't get hung up on it" ;)
Brian
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Kramer, it's a 4-cycle engine. Suck, squeeze, bang, blow. 2 TDCs per combustion.
In the cycle you're imagining, ask yourself when the inlet opens.
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Yes there is overlap at TDC when transitioning from the exhaust stroke to the intake stroke. The exhaust valve stays open past TDC as the "inertia" of the exhaust gases flowing out the exhaust port continues to "evacuate" the cylinder. The intake valve opens before TDC to take advantage of this partial "vacuum" created in the cylinder by the exhaust gases rushing out. This is all simplified as it is a very complex system of pipe lengths, pressure waves, etc.
You do not calculate the overlap by subtracting how long one valve is open from the other as they are largely open at completely different times.
Unfortunately, however, the two valves will hit if they are both wide open, and hit any piston that is at TDC. This is why it is critical to have the cams in position before placing the head on the block. Having to turn the cams more than a few degrees usually means trouble. Wide open valves also extend past the head surface so you can, if the cams are in, bend a valve by simply placing the head down.
Have you done a compression test yet?
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it's a 4-cycle engine. Suck, squeeze, bang, blow
:FUNNY:
I just love that description..... and so apt for a Lotus engine
Brian
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Problem 1
So it finally runs!! ...but not well. Timed valves to -26 BTDC IO and +26 ATDC EC, just like the manual. Ignition seems to be happiest firing between 5-10 BTDC, but don't ask it to idle for more than 10 seconds, even at full choke. Runs smoothly between 2000-4000rpm. Below 1500 and it starts to shake and sputter. Below 1200 and the shaking gets really bad. Dies when below 1000 for longer than a few seconds. Have not done a formal compression test, but I can tell you that when manually rotating the engine by turning a rear wheel it becomes difficult to rotate the wheel when a chamber is in its compression stroke.
Problem 2
The brand new head gasket and cam cover gasket I bought from R.D. leak very badly. For the head gasket I strongly suspect the sealant is to blame. For the cam cover an apparent warped or mis-shapen face of either the cam block or cover is to blame for the gasket leaks. With the cam cover nuts torqued to spec I can FREELY slide the gasket back and forth under the cam cover in the spots where it's leaking. Either the face of the cam block is warped or the cover is. The cover leak should be remedied with a better bead of sealant, but I'm going to have to remove the whole block again to fix the head gasket leak...
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That's too bad about your gaskets. While you have it apart (again), I'd make sure that the head and the deck are flat before putting it back together. I assume you used a copper "asbestos" gasket. I used those in the dark ages on my MG F-Production racing Midget. I don't remember using any sealant but I could be wrong - that was a LONG time ago!
A compression test and a leakdown test before you tear the engine apart would be useful. You might have a carburetor problems.
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I assume you used a copper "asbestos" gasket. I used those in the dark ages on my MG F-Production racing Midget. I don't remember using any sealant but I could be wrong - that was a LONG time ago!
The old gasket I removed (installed in 91) was copper and asbestos, but I used a new style composite gasket which Ray at R.D. trusts. That's why I am initially blaming the sealant I chose. When I took off the original gasket there was no sealant used on it, but this new gasket recommended a thin sealant layer. Perhaps I didn't get it installed fast enough and it dried out in some places.
A compression test and a leakdown test before you tear the engine apart would be useful. You might have a carburetor problems.
The Zenith carb for the #1/#2 chambers definitely needs adjusting. The plugs in #1/#2 always foul quickly. However, the engine ran very smoothly before the first teardown last month, and I didn't do anything to the carbs except set them on the workbench, so I don't attribute anything major to the carbs that would cause the shaking and non-idling at lower RPMs.
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Check the carb diaphragms
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Check the carb diaphragms
Thanks. Both diaphragms look great. Very flexible and seal looks good. Carb oil is proper level and needles move up and down with ease.
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What do #1 and #2 foul with? Oil? If so, assuming you're using the correct heat range, you probably have a problem either with rings or valve guide/seal or some combination. If it's gas, you'll have to look at your carb(s) again. Make sure the butterflies are synchronized and the carbs have been balanced with a Uni-Syn or something similar.
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What do #1 and #2 foul with? Oil? If so, assuming you're using the correct heat range, you probably have a problem either with rings or valve guide/seal or some combination. If it's gas, you'll have to look at your carb(s) again. Make sure the butterflies are synchronized and the carbs have been balanced with a Uni-Syn or something similar.
#1 and #2 both foul with oil immediately upon engine start. They've fouled for a number of years but it wasn't something my father tried to fix because the engine ran fairly smoothly regardless, so he didn't give it too much concern and just lived with it.
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Hmmm... Their being next to each other and the fact that you have a head gasket problem might imply that you're leaking oil into #1 & 2 from an oil passage up to the head. I'm a little confused. A truly fouled plug will not fire reliably. Could it be that they are getting fouled worse than they used to? A leakdown test and a compression test may point you to the problem. Do you have new valve seals? Are your valve guides in good shape? Rings?
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The TC doesn't have any valve seals, it just hopes the machined fit between valve stem & guide and the cam bucket in the head is good enough to give a bit of lubrication and minimise oil loss. From my experience if it's worn valve guides then you get clouds of smoke well before the plugs start to foul up and affect running, so your conscience (and looks from other motorists) get to you long before the plugs start oiling.
So if they really are fouling with oil and not just an over-rich mixture then I'm with you on the head gasket or maybe bore problem and a compression test sounds like the best move. From the comments so far with clearances there sounds to be something wrong in the head assembly so after a quick compression test I think I'd be pulling it apart again.
Brian
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I'm a little confused. A truly fouled plug will not fire reliably. Could it be that they are getting fouled worse than they used to?
They are getting fouled just as they did in the past. I should perhaps call them "partly" fouled, because (before the tear down) the engine ran smoothly but smoked a little bit at low RPMs.
Many months before my tear down to replace the head gasket, I installed an electronic ignition, new plugs and wires. My father rarely serviced the vehicle, rarely drove it, and the last time he had replaced the plugs was nearly 10 years ago. But keep in mind he had ONLY driven about 3000mi (4800km) in 10 years on those plugs. Original plug #4 was covered in dry soot; #3 was light brown just as it should be; #2 & #1 were identical, both coated with about 0.5mm of burned oil.
I installed new Champion plugs and found that the new plugs resembled the old plugs after only about 20 miles of use! #1/#2 oiled; #3 great; #4 dry soot. Seeing that my brand new plugs had already been oiled is what finally pushed me to replace the head gasket. When I exposed the chambers I was very surprised to see that the #1 and #2 chambers looked pretty good. I thought for sure they were going to be nasty. After installing the new head gasket, #1/#2 still oil just as bad as before. However, the new gasket leaks in multiple places on the outside of the block, so I can assume it is leaking into the combustion chamber as well, possibly causing the oiled #1/#2. Old, worn head gasket = oily plugs. New head gasket installed improperly = oil plugs. I shall find out in the coming weeks.
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Almost never is a head gasket the reason oil is getting into a cylinder. Some engines suffer from oil leaking out like the Alfa fours but not the Lotus engine -- though there are plenty of places they do like to leak oil. The reason #1 & #2 looked good is that the oil is "washing" the cylinders clean. This most likely means that your oil control rings are toast or mis-installed.
Reading through this thread, it seems you do not have any experience working on engines. May I suggest you get some help? Please also do that compression test so frequently mentioned as there may be a bent valve or two
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Reading through this thread, it seems you do not have any experience working on engines. May I suggest you get some help? Please also do that compression test so frequently mentioned as there may be a bent valve or two
Much thanks for the advice. You're exactly right, unfortunately I don't have any experience working on engines, but sadly my finances will not allow me to spend the large lump of money required to tow it and have a professional mechanic fix the issues. But what I do have is ample time to study the manual(s), forums and other internet sources, and the ability to consult my two uncles who originally rebuilt the engine 22 years ago with my father and really ARE genuine mechanics (the car is over 1000 miles away from them now, though). I'm absolutely going to go buy a compression tester and research the proper procedure to measure. I'm afraid of what it'll reveal! I'm fairly certain a valve is not bent, as I painstakingly researched beforehand the proper way to remove and handle the valve block so as to ensure safety of the fragile valves...but you never know. Will be a few weeks before I can resume work on it. Thanks once again.
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No need for professionals but anyone with some familiarity with twin cam engines would help. If they rebuilt the engine and it's been oiling #1 & #2 plugs ever since, it is possible they put the oil control rings in upside-down. I have seen that happen quite a few times. You can usually borrow/rent tools from some auto parts stores so there is no need to buy a tool that will see limited future use.
Also, when you remove the head, the chain falls off the crank sprocket and when you go to put it back on, the auxiliary shaft (which drives the distributer) will not be in the same position: just another thing to check.
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Interesting comment on oil control rings fitted incorrectly, however I would go back and consider that the fault definitely isn't any of these before a strip down.
1) carbs running rich or imballanced on 1&2 it seems too much of a coincidence to me that 1&2 fowl and not 3&4 and they are on one carb.
2) spark plug heat range, change to a hotter plug and use NGK plugs, (sorry my preference I find they are the best in my experience, neither Champion or Bosch can match them). A colder plug can easily fowl up and cause running problems. (This is an easy one to check, just get some hotter plugs of the same type, I can't recall the plug code numbers so can't post recommendation ). I have a tuned cross flow ford with twin dellortos on my Westfield, on track days I can run colder plugs as thrash it around, but around town it will play up with erratic tickover and missfire and more difficult to start as the plugs start to fowl.
3) did you change plug leads and dizzy cover?
All 3 of the above will compound each other