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From the Lotus 1980-87 Service Notes (aka Workshop Manual)
https://tinyurl.com/yxfsfvrl TDA
Download a copy
Although the 907 was out of production by the time the 1980-87 manuals were printed, its section TDA retro-actively covered the 907 with up-dated and more complete specifications. All 907 owners should have a copy of TDA.
Just to highlight a couple of additional points that are not specifically covered in TDA...
*~*~*~*
The J-H manual calls for torquing the cam carrier fasteners to 18-20 Lbs-ft. That's too high, and leads to stripped threads in the cylinder head. Lotus manuals specify a torque of 14-16 Lbs-ft (1.93-2.21 Kg-m or 19-21.7 N-m). Use the Lotus torque spec.
*~*~*~*
All J-H and Lotus torque specs for the cylinder head no longer apply to the current composite head gasket and studs. Either upgrade to Lotus' later head studs and use the later torque, or upgrade to the current ARP studs & nuts and use ARP's torque spec.
The current cyl head torques are higher, and will cause all original 907 head studs to stretch... both J-H and Lotus. All old head studs should be upgraded. While it is possible to use the current composite gasket with the old, lower torque specs (out of consideration for the old, weaker studs), doing so will not take advantage of the composite's gaskets superior capabilities.
Either...
1) Upgrade to the later Lotus head studs (B907E0224Z), and use the Lotus torque spec for the composite head gasket. With the Goetze Composite gasket. Note that Lotus' revised torque spec calls for the use of a Torque Angle Meter, instead of the previously specified torque wrench.
Cylinder head (tighten cold, oiled threads):
i) 20 Nm (light initial load using a torque wrench)
ii) + 75 Degrees (using a Torque Angle Meter, TAM)
iii) + 40 Degrees
iv) Wait 5 minutes
v) + 20 Degrees
Or...
2) Upgrade to the current ARP head studs & nuts, and use ARP's required thread lube and torque spec.
110 lbs-ft (15.2 kgf-m) All Studs, ARP Ultra Torque Lube applied to threads & washers.
Note that both the later Lotus and current ARP torque specs WILL cause the original 907 head studs to yield and stretch. Don't go there.
In all cases, start with the center pair of studs, and work out to the ends in a criss-cross pattern, as noted in all J-H & Lotus manuals.
Regards,
Tim Engel
Last edited on 06-03-2019 09:25 pm by Esprit2