Hey guys

I'm trying to put the engine loom in my ute and I'm having trouble figuring out what bolts are meant to go in the firewall (red circles in attached pic (stolen from tongy)). They look like 6mm, but the thread seems wrong and I don't really want to mangle it. Might be time for me to invest in some thread guages but figured you guys would prolly know...

Also having the same trouble with a weber I bought off ebay. Have fitted it on to my manifold and everything, but can't attach the air filter bracket as the bolts don't seem to fit. See photo of this too.

Be very grateful for advice, cheers.

Attach file:

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  underbonnet.jpg (60.80 KB)


  weber.jpg (34.20 KB)

Just realised the photos aren't so hot - an example of the hole I'm trying to measure are the ones that hold the coil bracket on.

There are two metric thread pitch.

6 x 1.25
6 x 1.50

Later ute Coil bracket screw is 08513-61612

51 Tapping screw, Pan head
36 Dimension, 6mm
16 Length, 16mm
12 chrome coated

OK cool... so for the bracket one, if I go to a nuts and bolts place, do I ask for a 1.25 or 1.50 pitch?

probably 1.25, that's most common.

You might find the 'bolts' holding the coil to the firewall are actually self tapping screws with a hex head. Or they could be a 6x1 metric thread which is what the bolts holding the windscreen wiper should be. As for the bolts for the DGV weber, they'll be 5mm metric thread. It's best to get studs for this, as you can damage the thread if you're constantly doing up & undoing the bolts. Also try & get nyloc nuts, as any nut that comes off could go down the carby. It'd be best to find a fasteners supplier, take the carby along & buy some studs & nuts off him. You should be able to find someone in the yellow pages under fasteners.

they are m6 mate 1.25 pitch

Everything Nissan I have ever used has been M6x1, it is the most common pitch.
If you go to a bolt store and ask for a 6mm bolt and don't specify a pitch.
You will leave with M6x1.

If you need 5mm bolts for the webber, the standard 5mm bolt size is M5x0.8

I did a write up on metric threads on another site the other day, Here is a copy of what I did...


What the numbers mean.

All metric threads have a prefix of M, this means metric. All numbers there after are represented in millimeters

The number(s) directly after M represent the Nominal Diameter of the bolt and the number after the X represent the pitch of the thread.

*Nominal Diameter - The true bolt diameter is a little smaller and the true nut diameter a little larger
*Pitch is distance between threads

Example for a bolt with a thread of M6 x 1.

M6x1 Nominal Diameter = 6mm
M6x1 Pitch = 1


How to work out "Tap Drill Sizes" for metric threads.

Tap Drill Size = Nominal Diameter - Pitch


Formula for a bolt with a thread size of M6 x 1.
Tap Drill Size = Nominal Diameter - Pitch
Tap Drill Size = 6 - 1
Tap Drill Size = 5mm

Common Tap Drill Sizes (Metric Coarse)

M3 x 0.5 = 2.5mm
M4 x 0.7 = 3.3mm
M5 x 0.8 = 4.2mm
M6 x 1 = 5mm
M8 x 1.25 = 6.75mm (Use 17/64 inch = 6.747mm) alternativley use (use 6.7mm or 6.8mm)
M10 x 1.5 = 8.5mm
M12 x 1.75 = 10.25mm (use 10.2mm or 10.3mm)


Common Tap Drill Sizes (Metric fine)

M8 x 1 = 7mm
M10 x 1.25 = 8.75mm (Use 11/32 inch = 8.731mm) alternativley use (use 8.7mm or 8.8mm)
M12 x 1.25 = 10.75mm (Use 27/64 inch = 10.716mm) alternativley use (use 10.7mm or 10.8mm)


Additional info.

The thread angle is 60°. The thread depth is 0.614 x pitch.

There are three kinds of ISO metric threads:

coarse
fine
extra fine