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renovated engine burning oil  Rating:  Rating
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 Posted: 03-20-2015 06:07 am
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Barthol
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Hi Guys,

After installing my 2,2 renovated engine i really understand why people says that stroking the engine is the single best thing to do to increase performance, Torque is dramatically imroved.

My only problem is that it is smoking a lot during acceleration ( blue smoke)
I received the bottom end of the engine rebuild and the cylinderhead also rebuild but not mounted.

Looking down the cyl there was clear honing marks.( I do not know if the rings were changed)
Cylinderhead looked good with a few new valves ( indicates t me that someone have gone through the troubles and checked the Clarences in the valve guides etc)
There is no oil sealings on the valves,- is that even available for the 907 engine?

Compression on all 4 cylinders is 190 psi just by using the starter to crank the engine and with throttles fully open.
It starts , idles and runs very nicely , with only a little explosions from the exhaust on the overrun. Carbs are 45 dellortoes .

I have taken of the inlet manifold to check the inlet valves and the stems looks nice and dry.
Engine venting from the cranck housing is breathing ( it is connected to the airlifted box ) The vent from the valve cover is creating a little more vapor

Any Ideas on where to continue looking , I would hate to swap back the old 2.0 engina as the 2.2 is a real improvement in terms of performance.

BR
Kim

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 Posted: 03-20-2015 09:32 am
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gmgiltd
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Hi Kim,
Chances are that it will use oil for several thousand miles untill it is fully run in. Most modern engines don't require the full regime and only advise you to avoid full throttle for the first five hundred miles or so.
Stay off synthetic or semi synthetic oil for at least three thousand or the bores will never bed in. Take it easy for the first few hundred and gradually increase rpm and load over the next few thousand miles, trying to vary as much as practical. Once it's fully run in they still use more oil than modern engines most of the recent ones I have had don't use any between services - up to 20k in some cases.
Gordon

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 Posted: 03-20-2015 09:54 am
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Barthol
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Hi Gordon,

I run it on Mineral oil 15/40. And the smoke is a lot, not in idle but during acceleration 2-3000 rpm . I have only done 200 km since the rebuild, so maby I should just continue to run it for some longer trips to see if the blue smoke clears :-)

BR
Kim

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 Posted: 03-20-2015 09:54 am
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Barthol
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Hi Gordon,

I run it on Mineral oil 15/40. And the smoke is a lot, not in idle but during acceleration 2-3000 rpm . I have only done 200 km since the rebuild, so maby I should just continue to run it for some longer trips to see if the blue smoke clears :-)

BR
Kim

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 Posted: 03-20-2015 11:03 am
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subwoofer
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The "run it easy for two thousand miles" break-in routine is disputed, there is at least one other school of thought. Below is probably not the best reference, but it advocates the method I believe in.

http://www.mototuneusa.com/break_in_secrets.htm

I have also met train guys who say that when the diesel locomotives starts using oil the best thing to do is to load them hard for a day or two, that usually takes care of any glazing on cylinder walls.

--
Joachim

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 Posted: 03-20-2015 12:35 pm
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Barthol
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Hi Joachim,

Interesting reading.
On my old Bikes I have used something in between.
Running it through the gears, but gradually increasing RPMĀ“s being very carefull to not let the engine pull from to low revs and keep changing the load on the engine.
However never full throttle for the first 3-5 runs:-)

I have purchased a USB endoscope and attached a Photo of cylinder 2. I clearly shows a little oil on the rear left side of the piston.

Can this come from the piston rings / or from the valves?
Is there a chance it will stop when the Rings have bedded in.
Or should i take out the engine and physically check the rings.
I have not mounted the pistons myself.
Please consider that I have 190PSI compression pressure on all 4 cylinders:-)

BR
Kim

Attachment: piston 2.jpg (Downloaded 136 times)

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 Posted: 03-20-2015 01:46 pm
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gmgiltd
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Hi Joachim,
Loads of variables here petrol diesel air cooled or liquid cooled. Personally I would think that as the compression pressure is even at 190 then the rings and valves are ok for an engine that has just been built, glazing should not be an issue as the bores were honed 300km ago. The main thing is getting it up to working temperature so that the clearances are correct.
Gordon

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 Posted: 03-21-2015 03:22 pm
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Bfitz241
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just curious...what type of rings were installed? cast iron, chrome moly, anything "special"?

I know this is a stretch, but would you be able to do a leak down test on your engine?

Last edited on 03-21-2015 03:24 pm by Bfitz241

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 Posted: 03-21-2015 03:57 pm
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Bfitz241
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I think I'm going to side with gmgiltd, this engine only has about 120 miles on it....but if it continues

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 Posted: 03-21-2015 05:52 pm
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Barthol
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Found the error.
I ran the engine for a little while closed the throttle and just rolled to a stop in 2 gear,then immediately removed the inlet manifold. I found oil on the inlet valves in 2 cylinders.( a nice little amount)
I guess that the engine goes out again for a cylinder head job.

Is it possible to install oil sealings on the stems / guides?

br
kim

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 Posted: 03-21-2015 07:28 pm
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Jensen Healey
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I have seen valve guides with seals from various sources.

http://www.ebay.com.sg/itm/Lotus-Sunbeam-Esprit-Excel-Elite-Eclat-Bronze-valve-guides-stem-seals-/271054537358

The engine oil should be 20-50. This should help a bit until the head work can be done.

Kurt

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 Posted: 03-22-2015 05:43 am
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Esprit2
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The 907 is not supposed to have valve guide seals. The engine is designed for high rpm operation, and that requires adequate lubrication for the valves. If the guides are worn, installing seals might stop the smoking, but it also gives up the lubrication the valves need. If you're going to granny drive it to get groceries, go with the seals. If you wish to drive it as it was intended to be driven, fix the root cause problem... the valve guides and/or the valves (worn stems).

190 psi compression pressure is very good, so I suspect the rings and valve seats are sealing very well. Jensen-Healey specified checking the compression cold, and Lotus specified hot. For the same engine, hot produces higher pressure readings than cold does.

8.4:1 cr = 7.58 - 8.96 bar (110 - 130 psi) COLD = Jensen-Healey spec
8.4:1 cr = 10.2 - 11.6 bar (150 - 170 psi) HOT = Lotus spec
9.5:1 cr = 11.2 - 12.6 bar (165 - 185 psi) Hot
9.44:1 cr = 11.2 - 12.6 bar (165 - 185 psi) Hot
10.9:1 cr = 11.5 - 13.0 bar (170 - 190 psi) Hot

Are the cylinder liners iron or Nikasil coated aluminum? The 190 psi implies the engine is a 1985-92 912HC, which is a Nikasil liner engine. If so, then the 10.9:1 compression, 180 Hp, and 166 Lbs-ft of torque would be a nice bump over the stock J-H 907.

Regards,
Tim Engel

Last edited on 03-23-2015 03:35 pm by Esprit2

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 Posted: 03-22-2015 05:55 am
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Barthol
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Hej Tim,

Engine is supposed to be a 1979 907 standard engine with the standard liners( they are iron- magnetic) / pistons, Liners is honed but I do not know weather the rings have been changed.
Crankshaft and rods are coming from a Bedford of some kind?
I meassured compression ratio to 9,5:1. Cams are something similar to 107/104 ( Reprofiled cams)
I measured my compression Cold by screwing the manometer into the plug hole, opening the throttle fully and crank the engine using the starter, until the reading stops increasing.

I think I will change the oil to a 20/50 mineral before i take out the engine.

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 Posted: 03-22-2015 05:59 am
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Barthol
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Hi Tim, Just forgot,

The car is NOT for Granny Driving.
In my opinion also old motors is supposed to be used as intended.
It will definitely see the red line once it has proven that it is dureble.

"Cars are for Driving"

BR
Kim

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 Posted: 03-22-2015 06:01 am
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Esprit2
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Good, they're more fun above 4500 rpm anyway.

The 104/107 cam combination is the same as was used in the 912 HC. I've not driven that combination, but I have twin 104 cams in one otherwise pretty stock 907, and twin Dave Smith DS2 cams in a hotrod 2.2 907, and both will happily scream right past redline. If the internals are built for it, the cams will pull 8000 rpm. The 107 cam... not so much. But the exhaust cam is less of a factor in determining the engine's personality, and the 104/107 combination is still pretty sporty.

Do you know if the Bedford crank is cross-drilled? The non cross-drilled crank isn't prone to running bearings at first flog. But the cross-drilled crank with the bearing shells that go with it are more durable if you're going to be using it's capability regularly. My 2.2 has a cross-drilled crank, but my two 2.0s are non cross drilled. Lotus Elite, Eclat & Excel (LC) were considered more civilized, and got non cross drilled cranks. The Esprit S1-S2, the Excel SE, and Turbo 910 were considered more boy-racer, and got cross-drilled cranks.

The 190 psi 'COLD' is high for 9.5:1. Lotus specified 190 psi 'HOT' for the 10.9:1 CR... but don't complain, higher is better.

If the cylinder head has been skim cut for flatness (.020" max allowed for the 907), the result would have been about a half a point increase in compression ratio (9.5:1 becomes 10.0:1).

On the other hand, the modern composite head gasket's crushed thickness is about 0.020" more than the original gasket, so it lowers the compression by a similar amount.

Tim

Last edited on 03-22-2015 06:27 am by Esprit2

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 Posted: 03-22-2015 10:15 am
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Barthol
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I have no idea on how the bottom end is built . It was done from the Guy in Uk from who I bought the engine :-(

How do I tell whether the Crank is cross drilled and have the right bearings, is it easy to see if I open it up any way ?

If I pull the engine out again and need to install my old engine I need to sort an issue with the belt tightening wheel . The bolt is pulling a little to the left when I tighten the belt. The thread in the engine block is not so good.

I have a semi automatic tightener but I cannot find out how to mount it. It looks like I am missing threaded hole in the engine.
Is there anyone who have som photos / schematics showing how it is mounted. ?

BR
Kim

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 Posted: 03-22-2015 08:40 pm
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Esprit2
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Barthol wrote: I have no idea on how the bottom end is built. It was done from the Guy in Uk from who I bought the engine :-(

How do I tell whether the Crank is cross drilled and have the right bearings, is it easy to see if I open it up any way?
Can you get back to the guy you bought the engine from and ask about the crank & bearings?

Pulling the cylinder head for a rebuild has nothing to do with the bottom end. Deciding to tear it apart just to check whether the crank is cross-drilled or not is totally unrelated, and optional. A non cross-drilled crank is not a fatal flaw, and is not necessary for an engine that is street-driven in a way that doesn't result in you knowing every judge on a first name basis. True, if you plan to flog it hard as a part of your daily driving style, then a cross-drilled crank and the lower bearing shells that go with it would be better.

If the engine had individual main bearing caps, like most engines, then you could simply drop the sump, pull one cap, and take a look. However, the 9XX engines use one large Main Bearing Panel that captures all the journals at once. Removing it pretty much requires disassembling the bottom end. From what you have described, I don't think it's worth your effort. Instead, ask the guy who built it.

"IF" you do tear it down for a look, then journals 1, 2, 4 & 5 of a cross-drilled crank will have two holes in the journal, 180 degrees apart. They are the opposite ends of the one drilling that passes all the way through... you can slip a slender rod (screw driver) through it.

A non cross-drilled crank will have only one hole in those same journals. It's drilled at an angle to the rod journal.

The lower bearing shells are for a cross-drilled crank are plain. No oil hole. No oil distribution groove. That's the point of cross-drilling. It allows the surface area of the lower bearing shell to be maximized to support the piston & rod's downward thrust forces by not giving up area to oil distribution. Then the cross-drilled passage in the crank takes care of distributing the oil.

For a non cross-drilled crank, the lower bearing shells all have a central groove to distribute oil. It does it's job well, but takes away some surface area that would otherwise be available for supporting piston & rod thrust loads.

In all 907s, the upper bearing shells have both a groove and a hole.

907 with NON cross-drilled crank
Upper:
Groove/Hole - Groove/Hole - Groove/Hole - Groove/Hole - Groove/Hole
Lower:
Groove/Hole - Groove/Hole - Groove/Hole - Groove/Hole - Groove/Hole

907 with cross-drilled Crank
Upper:
Groove/Hole - Groove/Hole - Groove/Hole - Groove/Hole - Groove/Hole
Lower:
Plain ............. Plain ............. Plain ............ Plain ............ Plain

912 with NON cross-drilled crank
Upper:
Groove/Hole - Groove/Hole - Plain/ Hole - Groove/Hole - Groove/Hole
Lower:
Groove/Hole - Groove/Hole - Plain ........ - Groove/Hole - Groove/Hole

912 & 910 Turbo with cross-drilled crank
Upper:
Groove/Hole - Groove/Hole - Plain/ Hole - Groove/Hole - Groove/Hole
Lower:
Plain ............. Plain ............. Plain ............ Plain ............ Plain

Regards,
Tim Engel

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 Posted: 03-22-2015 08:48 pm
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Esprit2
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Barthol wrote:
If I pull the engine out again and need to install my old engine I need to sort an issue with the belt tightening wheel. The bolt is pulling a little to the left when I tighten the belt. The thread in the engine block is not so good.

I have a semi automatic tightener but I cannot find out how to mount it. It looks like I am missing a threaded hole in the engine. Is there anyone who have some photos / schematics showing how it is mounted. ?
It doesn't take long for a credible machine shop to rebuild the head (new valve guides... maybe new valves). You'll need to allow a week for new parts shipping, and the shop may have a job waiting list. The parts shipping time will probably fit into the waiting list time. If you pull the head, get it rebuilt, and put it back on, the engine will not be out of service long enough to justify re-installing the old engine. Don't bother. Just pick one path, and git 'er done.

Regards,
Tim Engel

Last edited on 03-22-2015 09:26 pm by Esprit2

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 Posted: 03-22-2015 09:36 pm
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Jensenman
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Barthol wrote:
Found the error.
I ran the engine for a little while closed the throttle and just rolled to a stop in 2 gear,then immediately removed the inlet manifold. I found oil on the inlet valves in 2 cylinders.( a nice little amount)
I guess that the engine goes out again for a cylinder head job.

Is it possible to install oil sealings on the stems / guides?

br
kim


This sounds to me like the valve stem to guide clearance is excessive, i.e. it needs new guides and possibly some valves. I would not recommend using valve stem seals, the 'bucket' tappet setup already restricts oil to the valve stems.

Also, is there any reason not to rebuild the head from the original engine? Have that head reworked then spend a Sunday afternoon swapping heads. Well, since you'll need to adjust the valves make that a Saturday and Sunday.

Last edited on 03-22-2015 09:39 pm by Jensenman

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 Posted: 03-22-2015 09:48 pm
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Esprit2
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Barthol wrote:
(Snip)... I need to sort an issue with the belt tightening wheel . The bolt is pulling a little to the left when I tighten the belt. The thread in the engine block is not so good.It sounds like you're talking about an eccentric tensioner here. All later J-H Mk II 907s, and all Lotus 9XX engines with eccentric tensioners use a stuc to mount the eccentric. I've not worked on a J-H Mk I (rope seal) 907, but my J-H parts manual calls out a stud and nut for mounting the eccentric. Does your engine actually have a bolt, or was that a casual mis-use of the term?

In general, it's a bad idea to use bolt for a high stress, repetitive application in an aluminum part. The soft aluminum threads will take the brunt of the abuse, and wear or strip in time. A better solution is a stud, since for most applications, it's a one-time installation. Then the repetitive wear part of the assembly is taken by the studs steel threads, and little wear takes place.

If the 'bolt' can wobble about, then it sounds like the threads require a repair insert. In that case, a threaded barrel insert (like a Time-Sert) is superior to a more common Heli-Coil.

The stud needs to be perpendicular to the block's front face, and drilling the hole to accept an insert is not a good job for a hand-held drill. Taking the block to a machine shop to have the threads properly inserted will require a complete tear-down.

As an alternative (it's worth a try), apply Blue Loctite 242 to the threads in the hole and on the 'stud'. Screw the stud into place and torque it to 20-25 Lbs-ft. Wipe off any Loctite that oozes out. Lightly wipe the eccentric with oil (especially it's bore) so that any Loctite residue you miss will not stick to it. Install the eccentric and tighten it's nut to 30 Lbs-ft. Allow it to sit undisturbed for 24 hours for the Loctite to fully cure. The tension should pull the stud up square to the surface, and the Loctite should hold it in position.

Remove the eccentric, then go about fully installing the timing belt.

Regards,
Tim Engel

Last edited on 03-22-2015 09:49 pm by Esprit2

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