5 replies to this topic

[JimmyStinkpickle]

Hi all, I am preparing to install the crank for my 1293 A+ build and was wondering if the factory main cap bolts should be torqued dry or with lube? Machine shop suggests using ARP lube torqued to factory spec (63ft/lbs), but the Haynes manual specifies no lubrication so I am assuming they are fitted DRY? To add to the confusion, the Bill Sollis tutorial shows him lubing the bolt threads with conventional oil torqued to 68ft/lbs. Can anyone please clarify which method is correct? Thank you.

Edited by JimmyStinkpickle, 07 May 2025 - 05:24 PM.

[DeadSquare]

It probably doesn't matter in the great scheme of things, bit I have always lightly lubricated the bolts.

[JimmyStinkpickle]

It probably doesn't matter in the great scheme of things, bit I have always lightly lubricated the bolts.

Thank you for your advice DeadSquare. As this is my first engine rebuild, I am trying to do everything by the book. What do you usually torque them too? I've seen 63, 65 and 68ft/lbs from various rebuild videos. 

[Spider]

Lubricated.

The bottom end fasteners using the factory bolts are lubricated with engine oil on the threads and under the head. The factory bolts are fine and fine to be re-used many times. The big end bolts and nuts should be replaced, while the factory fasteners were fine for this, genuine items are NLA. I've gone to ARP here as at least they are a known quantity and the cost of a broken bolt when swinging around will far outweigh the cost of a set of ARPs.

If you change to ARPs on Mains you will need to have the Mains Line Honed as the shape of the tunnel will change from the increased clamping pressure, likewise, in changing the Rod Bolts you'll need to have the Rods Closed and Honed, but as a matter of course when I recondition any engine, I always include the rods as part of that process, a Close & Hone, check the little end for condition and size, then check the rod for twist and bend.

The Factory Torque figures for A+ Mains is 63 lb/ft for factory bolts. If going to ARP, use their lube and follow their instructions, including the torque numbers.

[JimmyStinkpickle]

Lubricated.

The bottom end fasteners using the factory bolts are lubricated with engine oil on the threads and under the head. The factory bolts are fine and fine to be re-used many times. The big end bolts and nuts should be replaced, while the factory fasteners were fine for this, genuine items are NLA. I've gone to ARP here as at least they are a known quantity and the cost of a broken bolt when swinging around will far outweigh the cost of a set of ARPs.

If you change to ARPs on Mains you will need to have the Mains Line Honed as the shape of the tunnel will change from the increased clamping pressure, likewise, in changing the Rod Bolts you'll need to have the Rods Closed and Honed, but as a matter of course when I recondition any engine, I always include the rods as part of that process, a Close & Hone, check the little end for condition and size, then check the rod for twist and bend.

The Factory Torque figures for A+ Mains is 63 lb/ft for factory bolts. If going to ARP, use their lube and follow their instructions, including the torque numbers.

Hi Spider, I am indeed reusing the factory main cap bolts and the conrods were reconditioned and balanced with new ARP hardware from the machinist. Will lube the main bolts and torque to factory spec per your advice. Thanks again!

Edited by JimmyStinkpickle, 07 May 2025 - 09:07 PM.

[greenwheels]

The ARP Catalog looks a good technical read

https://arp-bolts.com/