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 Posted: 12-01-2020 03:15 am
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 547
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Sorry to hear you've run into problems.

FYI, the torque specs in the J-H Workshop manual for the Cam carrier nuts, and for the head nuts are too high. In Lotus' own manuals, the torque specs were lowered, but the J-H manual was never updated.

For the cam carrier nuts, use 14-16 Lbs-ft, not 18 Lbs-ft.

With the original, stock head studs, use...

70 lbs-ft Front & Rear Pairs, Oiled threads.
75 lbs-ft Three Middle Pairs, Oiled threads.

When the Goetze composite head gasket was introduced in Jan 1993, the required higher torque was too much for the original low-spec studs, so new stronger studs were introduced. With the composite gasket, USE the stronger studs, and the new higher torque.

IF you insist upon keeping the original studs, :-( then you have no choice other than to use the original low torque spec, above. That will protect the weak studs, but you won't get the new gaskets' improved performance.

The new torque spec requires the use of a Torque Angle Meter instead of a torque wrench (they're inexpensive).

Cylinder head tightened cold, with oiled threads & washers.
1) 20 Nm (14.75 Lbs-ft) initial preload with torque wrench.
2) +75 Degrees
3) +40 Degrees
4) Wait 5 minutes
5) +20 Degrees
I split #5 up into two steps of #10 degrees each.

if you go with ARP head studs, then use ARP's torque spec along with their own required ARP Ultra Torque Thread Lube on the threads as well as the washer/ nut interface.

110 lbs-ft (15.2 kgf-m), all Studs, with ARP Ultra Lube.

*~*~*~*
Lotus Technical Data Section A (TDA) was released in 1983 for all the naturally aspirated 9XX engines, including the 907, 911 & 912. Torque specs are on the last page.

Every 907 owner should have a copy, and you can download one from my Google Drive, here:

https://tinyurl.com/t7b872hr -- Edit: Replaced link Nov 16, 2021

For more complete torque specs, also download the following Excel Workbook. It contains multiple worksheets, so click on a tab across the bottom of the page to select one. There's a tab for Jensen-Healey. Use the torque specs for the J-H 'vehicle', but I suggest that you use the more up to date Engine specs in the Worksheet titled, "Engine - Lotus 9XX 4-Cyl".

https://tinyurl.com/2e3uzxw5 -- Edit: Replaced link Nov 16, 2021

Regards,
Tim Engel

Last edited on 11-16-2021 07:39 pm by Esprit2