Nutty Questions

[Dennis Vogel]

I'm trying to get clarification on a couple nuts for our 1960 Super 90 engine.

1. Should the two nuts used to hold down back side of the generator stand be 14mm ATF? That would match the bolts in the front.
2. What are the correct nuts to secure the flapper boxes? Pellow says these are 12mm ATF. So it requires quantity of eight M8x12 nuts? I think I am fresh out of those, and am not able to find a reference to these in the parts catalog.

Thank you.

[steven mclean]

Jbugs.com has 12mmm copper nuts set of 8 $5.95

[David Jones]

Lifetime supply, careful with the copper VW nuts as they are designed to lock in place and can be difficult to remove.
https://smile.amazon.com/Plated-Finish- ... 310&sr=1-1

[Dennis Vogel]

Jbugs.com has 12mmm copper nuts set of 8 $5.95

Thanks for the suggestion, but I’m going to guess copper nuts are not authentic.

Are you confirming the size is correct?

Thanks.

[Martin Benade]

Which part do you mean by flapper boxes? The lower air channels? Or do you mean the muffler and J pipes?

[Craig Richter]

Copper nuts are not authentic anywhere on a 356 motor that I recall, although you do see them a lot now on exhaust systems. Jack taught me to use 12mm nuts on the exhaust because they are much easier to do/undo. 14mm ATF is correct nut for rear of generator stand, until they got to 912's and changed everything to 13mm.

[Dennis Vogel]

Which part do you mean by flapper boxes? The lower air channels? Or do you mean the muffler and J pipes?

Hrm. I'm not sure how to answer that. It's two parts connected, then mounted to the heads. I've seen them referred to flapper boxes (air guide in the parts book) and J-tubes (heat control box in the parts book). In the installation process I'm following, the J-tubes are already connected to the flapper box. The nuts are put on the exhaust manifold studs of 1 and 3 cylinders to secure the j-tubes. Then I believe the muffler will connect to 2 and 4 cylinders later.

I wish I could find the nut referenced in the parts catalog. Maybe the only references is on the muffler diagram #8 (502.08.310 - Hexagon nut
M8). I assume the same nut would be used on the other side?

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[Dennis Vogel]

Copper nuts are not authentic anywhere on a 356 motor that I recall, although you do see them a lot now on exhaust systems. Jack taught me to use 12mm nuts on the exhaust because they are much easier to do/undo. 14mm ATF is correct nut for rear of generator stand, until they got to 912's and changed everything to 13mm.

Thanks Craig!

[Craig Richter]

Dennis, You don't even have a picture of a "flapper box" on you post. Yes, I think "air guide" is the proper name. It would fit into that big hole on the sheet metal bowl surrounding the J tube, and is held on with a 6mm bolt almost exactly where number 1 is pointing. There is also one more 6mm bolt holding it on near the fuel pump if you had a picture. All 8 nuts holding the exhaust to the heads are the same 8mm (12, 13 or 14 ATF according to your mood, I guess).

[Harlan Halsey]

Brass nuts were used on 547 Carrera exhaust headers. Ever since I removed the rusted steel exhaust header nuts on my first 356 engine, I have used Mercedes Benz 12mm copper (plated?) locking nuts available from Global Metrics.

[David Jones]

The only sensible option for the exhaust manifold nuts are 12mm atf. Do not use the lock nut variety you will regret it. Try belmetric for the correct nuts.

[Craig Richter]

+1

[Dennis Vogel]

Dennis, You don't even have a picture of a "flapper box" on you post.

You are correct. That was intentional. It is on a different page from the J-tube, and I can't find a corresponding nut on the flapper box page. Sorry for any confusion. Included here for completeness #30.

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[Martin Benade]

So # 30 is what you want nuts for? It is only held on with 6mm bolts or screws. No nuts that aren’t welded in place.

[Harlan Halsey]

David and Craig,
I'm not sure what atf means but I can assure you that the copper plated 12mm mechanical lock nuts used on Mercedes Benz, at least that's where I found them, work fine for a very long time.