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Geotze head gasket stock studs torque specs ?


s1guy

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  • 2 weeks later...

Just saw this. Be careful with the gasket fitting. The manual advice doesn’t really apply to the new gasket. My take having asked just about everyone and experimented myself is this. 
 

Goetz gasket liner nip should be within 2 thou and not 4. ( from gasket manufacturer) The original gasket allowed a greater tolerance. If its 4 thou it will probably be ok if you smear the Goetze gasket with  gasket maker or Wellseal and get the torque setting correct.  Without sealant there is a small chance of gasket leakage probably water escaping up the studs. 
Most importantly I have experimented with the torque settings. With the old studs and having spoken to more than one expert I believe using a torque wrench is fine to the manual settings.
With new torque to yield studs it is essential to torque to angle. I measured the torque using a torque to angle method and it resulted in far higher torque settings than the manual states. It seemed to compress the gasket a lot more. Using a normal torque method with the new gasket, torque to yield studs and standard torque settings in my view is very risky. Obviously do your own research, but I would say smearing the gasket is a really good idea! 
 

 

 

 

 

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  • 6 months later...

I was under the impression that when you install the Geotze gasket you must upgrade to the newer head studs or the ARP ones.  Reason being, the. Goetze gasket requires a greater clamping force over the old metal gasket. The old studs are not up to the task.

Tim Engle….

the current Goetze composite gasket requires high-strength cyl head studs, and the nuts are tightened with a torque angle meter, not a torque wrench. Using the old torque wrench spec won't get the head tight enough for the new composite gasket.

Use a Torque Angle Meter (initial set with a Torque Wrench)
Initial Load = 14.7 Lb-Ft / 2.0 Kg-m / 20 N-m (torque wrench)
Then, using a Torque Angle Meter.
Tighten an additional 75 in one step, then.
Tighten an additional 40. Wait 5 minutes, and then.
Tighten an additional 20

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No you don’t have to the specialists don’t replace the original studs unless they are damaged. Newer studs are torque to yield, which is a different torquing method and requires and angle meter, as above. 

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Lotus Service bulletin 1993/07

TITLE:            Introduction of revised cylinder block, head & gasket

REASON:       Quality improvement.

                      The cylinder block and cylinder head of the Lotus 910/920 engine have been re-cast and upgraded in respect to stiffness, lightness, cooling efficiency and dimensional control. In addition, a new type of cylinder head gasket has an increased tolerance to severe thermo-cycling, and improved durability.

ACTION:        The new components have been introduced on engine serial number: 28096 (last 5 digits of engine number) - January 1993.

With the exception of the block deck height and various core and blanking plugs, the new block and head share all functional dimensions with the old type, and when service stocks of the older components are exhausted, the new parts will replace them. 
New heads may be fitted to old blocks and vice versa, but the new head gasket should be used in both cases.


The new block and head may be readily identified by cast Lotus logos on the front and rear faces of the cylinder head and at the top right hand rear of the block.
 

Cylinder Head Gasket

The steel and asbestos laminated gasket, B907EO026Z (Coopers - silver incolour) has been replaced by a reinforced fibre-composite gasket A912E7029Z (Goetze - grey/brown in colour) 
This uses a built-in silicone sealing bead around the periphery and a
 Viton seal around the oil feed hole. 
The compressed thickness of the new gasket is approx. 0.5 mm (0.020") greater than the old gasket and the deck face and liner seats of the new cylinder block have been lowered by a corresponding amount.


Service Replacement

i)   New engines must be fitted only with the new type gasket. Fitment of an old type gasket to these engines may result in piston foul and/or detonation due to the raised compression. 

ii)   When stocks of the old gaskets are exhausted, old engines should be fitted with the now gasket, which will also replace the 'extra laminate' thicker gaskets (A911E1292, B911E1292) used on some low compression 912 N.A. engines.

Note that the extra thickness of the Goetze gasket will result in a slight reduction in compression ratio (typically about - 0.5 numerically) when used on old engines. 
This may be advantageous to fuel octane tolerance, especially if the head face has been machined to correct distortion or erosion.



Goetze Gasket Fitting Procedure   

There are two points to note when fitting the new type gasket to new or old type engines:

a)       New engines must be fitted only with the new type gasket.

b)      The cylinder head nut tightening procedure has been amended and requires the use of an angle gauge. A Sykes Pickavant tool under Lotus Part No. TOOOT1235 will be despatched and invoiced to all dealers shortly.

Use the latest type cylinder head studs (B907E0224Z) identified by the dimple machined in the top end. Tighten into the block (with oiled threads) to 37 - 41 Nm (27 - 30 lbs.ft).

Fit head gasket (dry) and cylinder head. Fit washers, oil head stud threads and fit nuts.

Using the existing tightening sequence (from the centre outwards; see Service Notes EB.7),

Tighten the head nuts in the following stages:

i)        20 Nm (15 lbs.ft).

ii)                   + 75 degrees

iii)                  + 40 degrees

iv)                 Wait 5 minutes 

v)                   + 20 degrees

 
Cylinder Liner Adhesive

The sealant used between the base of the cylinder liners and the block (formerly Hylomar) has been changed to Loctite 572 adhesive/sealant (A912E7030V) in order to reduce fretting and noise; improve sealing durability; reduce the risk of liner disturbance with the cylinder head removed. The use of Loctite 572 has been introduced together with the new block and head castings, but may be used on all Lotus 900 series engines. Loctite 572 Application Procedure:

Thoroughly clean the liner spigot and seat, and the corres­ponding areas in the block.

Dry fit the liners and check that there is a nominal clearance between the top ends of the liners. 
Check the stand-out of the liners above the block deck face (liner 'nip') which is unchanged at: - 0.03 mm to + 0.05 mm (- 0.001 to + 0.002 in);


Maximum variation between adjacent liners: 0.03 mm (0.001 in)
Apply a small bead of Loctite around the seating face of the liner.
Apply a thin smear of Loctite around the outside of the liner spigot.
Apply a thin smear of Loctite around the top edge of the liner spigot bore in the block.
Slide the liners into the block and fit the cylinder head within 4 hours to ensure that the liners are seated correctly before the adhesive cures.
If this procedure is used on an “old” engine, apply a red paint mark for reference to the cylinder block at the end of the engine number stamping.

Note that when assembled as above, the liners will subsequently require the use of a liner puller tool (TOOOT0012A - existing part of the dealer special tool kit) in order to extract a liner from the block. 
The improved security of the liners also means that if care is taken, there is no necessity to reseal the liners in the normal course of cylinder head removal/refit


Cylinder head layout and orientation

Lotus Esprit cylinder head tightening sequenceLotus Esprit cylinder head tightening sequence                 
 
Summary
Vehicle manufacturers specify torque values for certain fasteners such as cylinder head studs and nuts. 
This is to make sure that fasteners are not over-tightened or under-tightened. 
The torque wrench is used to apply a specified amount of torque to a fastener. 
The torque angle gauge is used to make sure there is equal tightness across all fasteners on a particular component.

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