Jaguar Engine Hardware (bolt) Decoding

While buying bits of new hardware and attempting to tally up all the quantities of exactly which bolts I need for my '90 XJS V12 engine I think I have stumbled across a way to partially decode the part number of the bolts listed in the parts catalog.

For example: On diagram D11 (page 23 of my copy, made for 1987 on) part 16 is the Oil Galley Plug, part SH508051J. I have broken down the part like this:

SH - Screw, Hex
5 - Grade
08 - Number of 16ths in size of the bolt, in this case 8/16, or 1/2"
0 - number of whole inches in lengths of the bolt
5 - Number of 8ths in length of the bolt added to the previous number, in this case 5/8"
1 - Unsure of this one, perhaps whether the bolt is coarse/fine thread. In this instance it would be coarse.
J - Also unsure of this one, but it may have to do with finish.

I used the bolt pulled from the block to confirm all of the above is true.

This method also works for a bolt on the next illustration, D12 (Oil Sump and Dip Stick), same page. Part #25 is SH504081J, which would work out to:
SH - screw, hex
5 - Grade 5
04 - 4/16ths, or 1/4"
0 - Not over 1" long
8 - 8/8ths or 1" in length
1 - coarse thread

The bolt I pulled from that position (holding the adaptor that sits on top of the sandwich plate below the oil pump) is a 1/4-20 hex head bolt/screw 1" in length.

What do you guys think? I’d like to check all of these and see if they work, it would make finding replacement hardware from other suppliers/sources much faster.


when I looked through the parts to replace bolts for the coupe, I’ve been thinking there must a system to translate those PN to real sizes, but didn’t go this far : well done

the final letter could be either material or a finish (ie zinc coated steel, stainless…) or a key to check for mistakes in ordering systems (ie not significant for us)
iirc most bolts I ordered had the same letter, so the material / finish would be my bet

from what I’ve seen, SH is full thread screw, while BH is partial thread

@Craig_Balzer, any data on this, in your voluminous database?

I am not sure if this applies to the newer engines; I believe this is for E-Types.
Hope it helps

2. Decoding Fastners.pdf (123.9 KB)

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Correct, UK English: S = setscrew (threaded all the way)
B = bolt (has a solid neck, only threaded for some of the way)


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