Exhaust Manifold FO-4?

[Tomatoboy]

Um...are the exhaust/intake manifold remove and reinstall instructions omitted from the FO-
4 manual, or am I just having a bad reading day?

I apologize if this has come up before, I had trouble finding the torque specs and mine
needs replacement.

 

[HFJ]

i looked that one up the other day. 27 foot/pounds. don't ask me where i found it, i just remember it was a pain to find.

 

[Tomatoboy]

Thank you!

 

[Bruce (VA)]

The nuts are brass, 7/16-20 x 5/8, NAPA part number STN104X, 27 lbs of torque. Fastenal has them for about $1.50 each; part number 75133. OEM studs are 1-5/8 long 7/16-14. NAPA doesn?t stock the 5/8?s length, but part number RFD 86644, 1 ? inch, works as does part number 86632, 2 inches. These studs are ?Handi-Pack? items. (I?ve used these longer studs on my 50 & 51 N?s, but you should make sure they do not bottom out in the block on your N as they are longer than OEM). If you don?t get them at NAPA, make sure that the stud has an egg-shaped center between the different threads. Use washers under the nuts.

If you're really lucky, you can get the nuts off w/o removing a stud or damaging it. And, if you buy a ticket, you could win the lottery. Drain the block & plan on at least one stud getting replaced!

There are two distinctly different recommendations on tightening the studs in the block. Because the stud goes into the water jacket & is constantly undergoing extreme heat & cooling cycles, some folks like to double-nut them & tighten them down at 37 lbs of torque. Others say that it?s a stud & should only be finger tight w/ a good dose of thread sealer or high temp silicone on them.

I?ve replaced the studs on 3 of my 4 N?s w/ no leaks; I finger tighten the studs then take a ? turn on them w/ vice grips.
75 Tips

 

[Tomatoboy]

Good news! All four nuts came off with almost no effort. Oddly, three were wider than normal, but the ID was the same. Made it hard to get a socket in the small space the nuts hide in, if I?m honest. Not sure if those were ?heavy duty? or what, but I replaced them with OEM nuts and put everything back together. No more gasket leaks for me.