torque value for intake / exh manifold nuts

[merrill]

I was searching the forums for the torque values for the intake / exhaust manofold brass nuts and found many inquiries but not answers.

so I did a search on the internet and found the link below
http://www.engineershandbook.com/Tables/torque3.htm

they have a table for various nuts including brass.
based on the 13mm nut size which is roughly 1/2" the table has a torque value of 422 - 443 inch lbs. roughly 33 - 35 ft lbs.

I figured 30 lbs is a safe bet,  the real question is is this value too high for the cast maniflods?

matt

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[Paddy_Crow]

That sounds like a large fastener for an intake manifold or exhaust manifold. I wouldn't expect anything bigger than an M8 or maybe an M10. These days, intakes are usually M6 and exhaust are M8.

Make sure you know the size of the thread and the grade of the fastener, then look up the standard torque for that fastener.

Your best bet would be to consult a manual.

Democracy is two wolves and a lamb voting on what to have for lunch...

[al_lieffring]

quote:Originally posted by merrill

I was searching the forums for the torque values for the intake / exhaust manofold brass nuts and found many inquiries but not answers.

so I did a search on the internet and found the link below
http://www.engineershandbook.com/Tables/torque3.htm

they have a table for various nuts including brass.
based on the 13mm nut size which is roughly 1/2" the table has a torque value of 422 - 443 inch lbs. roughly 33 - 35 ft lbs.

I figured 30 lbs is a safe bet,  the real question is is this value too high for the cast maniflods?

matt

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

Matt

The torque specs listed on that (or any) table are based on the diameter of the threaded section of the bolt or stud, not the wrench size of the hexagon, In the case of the manifold studs, the locking nuts are 10x1.5mm threads with a 14mm hexagon.
The nuts that attach the header pipes to the manifolds are 8x1.25mm with a 12mm hexagon.

The manifold nuts are actually made of steel and have a copper plating, They also have a smaller than normal hex size for wrench clearance between the maniflods. These are a locking nut design and once they have been removed they should not be reused.

Al Lieffring
66 230SL

[merrill]

so i asked metric motors if they had a torque value for the intake / exhaust manifold nuts and they could not find the value in any of their mb books either.

they did recommend 40 ft lbs for the nuts

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230