O-200 Intake Manifold Nut Equivalent?

[farmrjohn]

Is there an equivalent 3/8" castle nut for the TCM part number 2458 for the O-200 intake manifold spider? Air Craft Spruce shows "no stock" and my google-fu wasn't successful finding another source.

 

[Dan Thomas]

AN310-6 works. In some engines, that stud is a bit short and the AN-320-6 can do the job.

Now, on that spider, there are supposed to be four Lock-O-Seal washers as part of the installation. Leaving them out and tightening up the nuts can lead to serious performance problems. From the O-200 overhaul manual:

 

[farmrjohn]

AN310-6 works. In some engines, that stud is a bit short and the AN-320-6 can do the job.

Now, on that spider, there are supposed to be four Lock-O-Seal washers as part of the installation. Leaving them out and tightening up the nuts can lead to serious performance problems. From the O-200 overhaul manual:

Thanks. I've read the posts about the need for the Lock-O-Seal washers. My spider appears to only have two, the ones on the bottom. There doesn't appear to be any washer at all between the manifold and the case. I was hoping a regular AN nut would work. Spruce lists the TCM part number but their price seems pretty dear at $54.01 each but they are out of stock anyway.

 

[Bell206]

successful finding another source.

Try Frenso Air Parts. They usually have a good stock of small Continental parts.

 

[Dan Thomas]

Thanks. I've read the posts about the need for the Lock-O-Seal washers. My spider appears to only have two, the ones on the bottom. There doesn't appear to be any washer at all between the manifold and the case. I was hoping a regular AN nut would work. Spruce lists the TCM part number but their price seems pretty dear at $54.01 each but they are out of stock anyway.

Without the top Lock-O-seals the manifold will rock enough to mess up the metal-to-metal interface between the manifold and case. You don't want that. Needs four or none.