How to remove cylinder hold down socket nuts,

These nuts would seem impossible to remove. They are 12 point socket nuts, not the hex nuts I have always seen and for which I have the offset wrenches. I have shown a conventional 5/8 wrench in one pic to show relative distance from the head of the socket nut to the fins. No way to get any tool I have in there.
Ed

These are the ones you'll need:
https://www.aircraftspruce.com/catalog/topages/nutwrenchs2.php

That's because you need a set of these wrenches.
ACS has them as do other shops.
You may be able to borrow them Maybe.
My luck varies. Art

Engine

Socket style nuts are used on narrow deck engines. Hex nuts on wide deck engines. Note the hold down plates under the socket nuts. For reassembly the hold down plates and cylinder flanges are only allowed a very light coat of zinc chromate. This is covered in detail in overhaul manual.

Right Tool for the job

Looks like everyone is pointing you in the correct direction for the proper tool for the job.

All I can add is that many of the less expensive tools may need to have a little material ground off so as to not rub the steel cylinder when you remove or install the internal wrench nut used on the standard (aka: narrow deck) cylinder flange engines. I believe that the newer 390 engine also use the same tool.

Tool

Thanks everyone for the reply. I guess I never noticed. Only older narrow deck engines have these nuts and I did not realize they even existed. Fortunately one of my EAA chapter mates saw this and responded that if I need them, he has the set I can borrow. Thanks Rick.
Ed

Absolutely do as JRS said. There can be no paint allowed between the spacer plate and cylinder, or under the nut. Only a very thin, max .0005 inch, coat of primer.

I met a rocket owner at Moose Creek Idaho that had lost a cylinder at Johnson Creek years before. Had a 540 narrow deck engine that was likely assembled wrong, blamed a Snap-On torque wrench. When it happens there are no clues except loose cylinder hold down nuts and maybe a little paint left under the spacers.

I lost two cylinders, a year apart, on a “professionally” built IO360 narrow deck engine before realizing this. The paint will fret away with a resulting loss of short stud torque, then unzip all the short studs. Occurs about 500 or so hours after cylinder installation. This is documented in the Sky Ranch Engine Manual.

You must also hold the spacer away from the cylinder with feeler gauges when torquing. This is not so clearly stated in the overhaul manual. Read the whole thing before working on an engine. There are many details, not necessarily in order, in the manual.

George

This:

444TX said:

Read the whole thing before working on an engine. There are many details, not necessarily in order, in the manual.
George

Click to expand...

And all the different models are covered on each page. I highlighted all the steps for my model to avoid any confusion.