Ok, I finally got around to replacing my fuel rail and a few questionable bolts and nuts. When I looked in my 75 280 service manual it says that the stock manifold 8 mm bolts torque is 10-13 ft-lbs and the 10 mm bolts are 25 -36 ft-lbs.  My manifold intakes are 14 mm bolts and the exhaust are 12 mm nuts?  What am  I missing  here?

Any clarification on size and torque would be appreciated.

Thanks

I think they're both m8 bolts, 22 nm.

Stud size vs nut size is all I can figure for your difference.

This is from Tom monroe's rebuild book, the bible.

M8 bolts have a 12mm head (JIS bolts anyway), M10 bolts have a 14mm head. Same for the nuts that would fit M8 or M10 studs. The four TOP bolts on an EFI intake manifold are M10 bolts, the studs on all the shared thick washer locations are M8.. Only the EFI heads have these M10 intake manifold bolt holes in between the M8 holes that are used on the carb intakes.

Edited May 30, 20204 yr by zKars

I bought the stud kit from MSA and it came with 13mm nuts on the 8mm studs.  Very annoying.  Nut size does not determine stud size.  (I know that sounds weird.)

Forgot to say that maybe the torque values are determine based on gasket crush, not the usual ultimate clamping force.  Determined by Nissan, not by the torque tables.

Edited May 30, 20204 yr by Zed Head

Those nuts with lock washers???

Waste of money.

Conical, one use nut in my opinion, is the only way.

Ok, couldn't see the forest for the trees.  What I fixed on was that the manual says" 8mm" and "10 mm". If they would have said M8 and M10  that would have made more sense. I know the exhaust manifold stud next to the fire wall can break easily (been there done that) and was worried about the torque in the manual.

Thanks to all for your input.