I am needing to know the size of a bolt that mounts the fuel rail to the engine(the bracket), lost mine. I am looking at the diagram but don't see the description on their site. Had to replace a rubber elbow coming from the oil separator (tough to put on). Great customer support every time I order from them.

 

Do you have the original bolt? or part of it with the thread? or is there another bolt of the same size in the assembly?
Measure the overall thread diameter using a vernier caliper or a micrometer to give you the physical diameter.
6mm : M6
8mm : M8
10mm : M10 etc
By the look of the diagram the fuel rail has two similar or identical bolts for mounting.
The bolt length is from the underside of the bolt head to the end of the threaded part.
If you have the other one of the two, that will give you the information.
But try out the other bolt in that location where the bolt is missing.

There are plenty of good bolt suppliers on ebay with vast ranges of sizes, types and materials.

The other information you need for another bolt is the thread pitch.
Either 1.0. or 1.25.
You need a thread gauge tool for this.
Always handy to have a gauge tool for metric and English threads.....

 

Ok It does look similar, I try can try that way and the other. I tried the bolt that mounted the lower plenum (m8 47 I believe) did not quite fit they were only size left and there mostly all uniformly same, working on the AJ6. I think all bolt belong in there proper places drives me nutz.

 

Just be extremely careful not to cause any thread damage to the housings.

If the other bolt fits then you can buy an equivalent spec bolt elsewhere. There is still the option to buy an OE part. Is there any threadlock on the bolts? Or they will be torqued up to a factory setting.

Just an observation from the diagram, the two mounting bolts look as if they have flanged heads. So you would need the same or to fit a washer to an unflanged bolt.

Fasteners are a whole science on their own. Having owned several classic motorcycles and a few newer ones, bolts and threads are something you learn about fast.
I've just about replaced every bolt on my current project bike with new stainless steel or titanium fasteners of higher than oem quality. Not difficult when you see the poor quality of bolts even on new bikes.

 

Ok I hear you loud and clear,wilco.

 

After gauging and measuring m6x1.0 bolt worked well, mounted to the engine pretty tight. Also on Bank 1 the bracket held down by the cam cover bolts uses the m6 bolt pretty well too. Mounted to the upper plenum pretty tight. Sorry lost my photos and phone during a huge concert .

 

I think you will find that jaguar do not list these bolts as separate parts. I think they come with the fuel rail!!
That will not help you much sorry!