1275 connecting rod nuts/bolts

[Blueghost]

Disassembly mode of 1275. Rod nuts seem to be a problem. 9/16 nuts. 12 point Snap-on 14 drive thin wall socket fits fine. 1/4 drive is clearly not what I want to use. Snap-on, older (better quality) S-K, and Craftsman 3/8 drive sockets simply will not even come close to fitting. Search on this web site for 1275 rod nuts turns up interesting data. There are some pictures of what I know to be called "space-saver nuts." These would be 12 point and 1/2 inch,not 9/16.

Question: has someone put the wrong nuts on these rods?
Are they supposed to be space-saver nuts?
I may be replacing bolts and nuts in overhaul. Assuming so, I can grind the old ones off. Pain in the posterior / time consuming / and I have no interest in damaging the cap.

I have used a Snap-on 3/8 to 1/4 drive adapter and enough force with a long breaker bar that I'm just short of breaking 1/4 drive lug. In fact, I'm surprised it didn't. Will not break loose.

Wrong nuts installed, and or needs a special tool. HELP.

 

[smaceng]

Hap can answer this question for you

 

[nomad]

Sounds as if you have after market rod bolt's fitted. Go buy a 3/8 drive thin wall socket and if it is still to thick I would just grind it down till it fits. Those bolt's would be worth saving, IMHO.

Kurt.

 

[Trevor Jessie]

Just buy an inexpensive 9/16" socket and turn down the outside a bit. Keep it in the back of the drawer for stuff like this.

OEM nuts are 6 point nyloc like you describe. Aftermarket ARP nuts are the 12 point that you've seen in the pictures.

 

[aeronca65t]

I have a 9/16" socket, turned down on a lathe. Just as JT has suggested. If you don't have access to a lathe, take an inexpensive socket and add an extension. Then chuck the extension in drill (1/4" extension with adapter will work best). If you hold against a grinder, you'll "turn" it down pretty quickly. Otherwise hold a good file against socket while it's spinning.

 

[Blueghost]

Thanks guys, Good to hear what was OEM and aftermarket (both good and bad). I judiciously applied a "hot" wrench (acetylene) to one nut on each rod. Was then able to use snap-on 1/4 drive thin-wall 9/16 socket. Nuts are going in recycle can anyway. Will be using 12 point ARP nuts. Once one nut on each rod was loose, the other nut came loose easy enough. I will be changing this string with new bad news problem encountered after dissassembly and cleaning. See "1275 Block Welding."

Blueghost

 

[nomad]

I misunderstood....thought they were 12 point nuts but my advise and others remains the same. If you have applied heat probably a good idea to replace the bolt's and nuts.

Kurt.

 

[Hap Waldrop]

I use a 9/16 socket I have ground down a bit to clear, thats just to take them off with, because I only use ARP for replacement,and it has undersize 12 point nut, so it now take a 12 point 7/16 socket, no clearance issue with the ARP nuts, the correct ARP part number for the 1275 #206-6001