Torque Angle Numbers???

[AZ88Turbo]

Hi,

Does anyone know the Torque angle settings for the head bolts on the 910 HC? I just replaced the head gasket and it blew again All surfaces are flat (had them machined) so I think it must be torque wrench I am using. I am told that a Torque Angle Meter is a better option but I need to know what the settings are in order to use it.

Thanks in advance for any help.

Mark (88 Turbo)

[lotusguy]

AZ88Turbo said:

Hi, Does anyone know the Torque angle settings for the head bolts on the 910 HC? I just replaced the head gasket and it blew again All surfaces are flat (had them machined) so I think it must be torque wrench I am using. I am told that a Torque Angle Meter is a better option but I need to know what the settings are in order to use it. Thanks in advance for any help. Mark (88 Turbo)

Mark,

If memory serves me, the torque angle for the 910 head is 20°-24°. But, be certain that the gasket you're using calls for a torque angle setting.

Torque angle is argueably more accurate a tension setting than using a torque meter, but there is no direct correlation between kgf./m, N/m, lbf./ft and torque angle. They are two distinct measurements.
As such, it is not possible to create a conversion chart. To use a torque angle meter, you must have a setting already determined by the gasket maker, and this setting would accompany the gasket. If you do not have this, stick with the torque wrench.

Also, both torque and torque angle measurements assume dry threads. If using any kind of form-a gasket, locktight or anti-sieze, you must reduce the torque by at least 50% since most of the torque called for is required to overcome the friction present in dry threads. Also, be aware that reducing the torque is always an arbitrary guess, so reducing it 50% may not be enough.

If using a torque wrench, be sure that you are torquing the bolts both in the proper sequence and also in steps. I like to divide the total amount of torque required into three unequal steps, going hard, then softer and then hard again.

If possible, try to arrange borrowing another torque wrench as a check against the one you've been using. Tests have revealed that it is not uncommon for a torque wrench which has not been calibrated in a while to be off by as much as 20%! And this can be in either direction! Using two can narrow the inaccuracies quite a bit. Hope this helps. Happy Motoring!...Jim'85TE

>> Edited by lotusguy on Thursday 20th November 18:50

[AZ88Turbo]

Hey Jim,

Thanks for the information. I had never heard of a "torque Angle Meter" until I saw one of your posts a while ago which said it was a better measurement. Just figured I would take your advice but I didn't see anything on the gasket or on the wrapper that said "torque angle settings". Think I'll stick to the torque wrench settings. I just bought another wrench to check it with. When I did them this last time they didn't feel very tight at all so I'm guessing my wrench may be on its way out.

Another quick question for you Jim; is there any reason that the head couldn't be lifted from the engine while it is in the car? It says ion the book that it is the exhaust manifold that is the problem why the engine needs to come out. That is why I took it out this last time. Looking at it though, it looks as if there is plenty of room if you take the head off while the exhaust manifold is still attached to the head (after the cam towers of course). Am I missing something?

I read on the other list also that I should run the engine for 15 minutes with no water so the gasket can seal. Does this sound like a good idea to you?? I’m just scared of burning something else up.

Thanks,

Mark (88 Turbo)

[lotusguy]

Mark,

I think sticking with the torque wrench is a good idea, and having two wrenches makes it more probable that it'll get torqued correctly.

To answer your question, it is possible to remove the head 'in situ', I know of people who've done it.

That having been said, I would not recommend it. The reason for this is that there is an excess amount of weight associated with the head and it's on a rather steep angle. I would fear not getting the gasket properly lined up, or scoring it.

I know that pulling the engine is a pain, but considering that the head gaskets on these cars are not exactly cheap, I would not be willing to risk having another one leak. I am certain that it will be a lot easier to get it right with the engine mounted on a proper stand. Imagine all the extra work, time and expense involved in doing the job over a third time should it leak again, yanking the engine can pale in comparison.

As far as running the engine dry, the only potential issue I see is possible waterpump damage if you were to run it dry for 10-15 minutes. I wouldn't worry too much about the engine internals so long as the oil is fresh and topped up. If you were to attempt this, I would remove the waterpump/vac. pump 'V' belt to prevent you having to spend another $200 on a waterpump rebuild. But, I have never found this to be necessary and have done a couple of these heads with no problems.

You say you had the head milled, how much? Lotus says that the head can only be milled a total of 0.040" and still be servicable. If the block was also milled, the combined total cannot exceed this limit. Milling the head more than this shortens the distance from the crank center to the cam centers upsetting the valve timing and requiring a switch to adjustable cam pulleys to restore it. Also, milling more than this can compromize the structural strength of the head. It may then move more under heat expansion than was originally designed. Was this head ever milled prior to your ownership?

About your current leak, look at the gasket to see where the leak is coming from. This may lead you to discovering a problem needing correction. Hope this helps. Happy Motoring!...Jim'85TE

>> Edited by lotusguy on Thursday 20th November 21:26

[Dr.Hess]

Having just gone through finding chocolate milk in the oil of my 92 Truck, I can feel for you, AZ. Also make sure it is the HG. Compression test on the cylinders indicating a BHG? Head OK/no cracks?

Dr.Hess

[sanj]

AZ88Turbo said:

Hey Jim, Thanks for the information. I had never heard of a "torque Angle Meter" until I saw one of your posts a while ago which said it was a better measurement. Just figured I would take your advice but I didn't see anything on the gasket or on the wrapper that said "torque angle settings".

If you are using the new-style head gasket, which is a brown composite material with gold-colored rings around the bores, you absolutely should use an angle gauge to properly torque the head. Lotus does not specify torque settings for this gasket. If you are using the old-style metal gasket then you should use the original torque settings.

Cheers,
Sanj

[AZ88Turbo]

I tested the head bolts with my new torqe wrench this morning, they were only tightened to about 50lbs. I thought it didn't feel too tight when I did it with my old wrench, guess it just goes to show that it is worth replacing my torque wrench on a regular basis.

I can't seem to find a torque angle wrench in any of the shops around here. I guess I'll take a look on the web and see what I can find.

Another quick question for you experts out there: I have heard it mentioned that a steel gasket is better then the brown composite. I have found a place that will custom-make a steel one, do you think it is worth the extra expense and wait-time involved?

Thanks for your help folks,

Mark

[sanj]

AZ88Turbo said:

I have heard it mentioned that a steel gasket is better then the brown composite. I have found a place that will custom-make a steel one, do you think it is worth the extra expense and wait-time involved?

Considering that Lotus changed to the composite gasket due to its "increased tolerance to severe thermo-cycling and improved durability", I'd say no.

As far as the torquing goes, you should be able to get an angle gauge fairly easily and inexpensively. Or you can make one with a sheet of paper and a protractor. It takes a great deal of effort to tighten the head to the correct value, so it sounds like you never got it close before.

Cheers,
Sanj

[AZ88Turbo]

Dr.Hess said:

Having just gone through finding chocolate milk in the oil of my 92 Truck, I can feel for you, AZ. Also make sure it is the HG. Compression test on the cylinders indicating a BHG? Head OK/no cracks? Dr.Hess

Hi Dr. Hess,

I'm pretty sure it is the head gasket. I just had the whole engine to peices because the head gasket blew last time. the compression test didn't show anything but I'm betting a leak-down test would have.

I'l just be happy to get my baby back on the road after a month of rebuilding.

Mark (88 Turbo)

[okc-esprit]

AZ - instead of replacing the torque wrench, have it recalibrated.

[AZ88Turbo]

Believe it or not I took a gamble yesterday; instead of taking the head off I just torqued it down to the correct settings then put it back together. I figured it was 2 hours of work risk for about the price of a new head gasket ($100), and it worked! It sealed itself and no more water in the oil!

I guess we'll see what it's like over time but for now I'm a happy camper.

Mark (88 Turbo)

P.S. I already bought the new torque wrench, the old one is now a long-handled wrench