|View single post by Esprit2|
|Posted: 04-27-2020 11:18 pm||
I posted that?
The tightening sequence is correct, center-out in a criss-cross pattern, regardless of the type of gasket used.
But the torque spec is for the Composite gasket with the Lotus 1993-onward B-prefix studs (identifiable by a spherical dimple milled in the upper end), and the Lotus-specified Torque Angle Meter instead of a torque wrench. The equivalent torque in lbs-ft would be similar to the ARP spec, but a little low.
If you're using ARP studs, then apply ARP's Assemblly Lube to the threads and to both faces of the thick washers. With the current ARP Assembly Lube, torque the nuts to 110 Lbs-ft (more on that below).
Always work up to the final torque level in several smaller steps. JAE recommended 30/ 60/ 110 ftlbs, and I wouldn't object to that. I torque them in four steps, with the final one being much smaller... from 100 lbs-ft in the 3rd step, to 110 in the 4th. Just a small 'finisher' step.
ARP has changed it's assembly lube formula a couple of times, modifying the coefficient of friction, then the torque spec was revised appropriately. The torque you use depends upon the lube you have. The ARP studs are all the same, the lube is the variable. If you have lost the instructions that came with your ARP studs & lube, then don't guess. Order some fresh, current ARP lube, and use the torque spec that comes with it.
Please point me to the message in which I posted the above illustration. It would be about right "IF" you owned a Torque Angle Meter and wished to use it per the Lotus spec. But ARP currently calls for a regular torque wrench, "their lube!!", and 110 Lbs-ft.
NONE OF THE ABOVE will work with original OEM J-H head studs. The later, 1993-onward Lotus torque angle meter spec (illustration in previous messate), and all ARP torque specs will yield the original studs.
If you have an early steel-asbestos-steel (SAS) head gasket (Bruce Madden has a few in stock), then do NOT use the torque spec given in the J-H Workshop Manual. It's too high, risks yielding the head studs, and crushes the SAS head gasket. For the SAS gasket, use Lotus' torque spec.
Lotus - With Oiled threads & washers:
(Original Steel-Asbestos-Steel Gasket)
70 lbs-ft ( 9.7 kgf-m) Front & Rear Pairs.
75 lbs-ft (10.4 kgf-m) Three Middle Pairs.
Last edited on 04-27-2020 11:28 pm by Esprit2