I have a quandry with the cam cover bolts on the 87 HE.

All the parts suppliers list the new bolts for my engine as 106251J based on an engine number of 8S049120HA. It is my understanding that this is an M6 metric threaded set screw.

One thing that is 100% for sure is that the set screws holding on my cam covers are NOT metric - I've had a metric pitch gauge on them - so if they're metric they sure as bears go in the woods aren't a standard metric thread.

I am not interested in obtaining more 'taptite' standard set screws so I've no intention of buying OEM but if I stick to my guns and order C35903/6 that's exactly what I'll get - I'm looking for socket head or torx preferably if such a thing exists in non metric.

Only problem is that I have no idea what thread profile or pitch these things are.

So what is the engine puzzle ? - the numbers on it - they aren't the ones on the log book which is above. These are the numbers taken from the top of the engine just by the transmission.

JLM0463SE = Part number - Clearly a high compression V12

3S2250F = What ? - I can find no such number in any Jaguar databases so far.

It looks like it has been stuck on but I've not tried (and won't) to remove it until I figure out what it is or why it doesn't align with anything I can find - is this a Jaguar warranty replace or something ?

And for those that say no such number

 

See attached. The new bolt part numbers along with the new design gaskets are what I used on my 87 HE V12. EDIT: They are metric thread. M6x1.0

 

If they are not metric then they will be UNC. Jaguar used both in the 1980s rather indiscriminately. To be sure test the old ones in a nut.

 

If my metric thread gauges won't fit them they're UNC, FS106251/J are metric based on my searches to date and that TSB (states that they're M6), a 1/4" should be a UNC 20 I think (1.27mm pitch).

Can only buy some and find out the hard way I guess ....

 

I made a HUGE mistake. The new bolts ARE metric, M6x1.0 x28 long, including the unthreaded portion at the tip. I'll correct my original post. Very sorry. I also have a 1987 HE, not an 86 as I originally posted. They are 8.8 strength. 25 or 30mm should work ok. The Jaguar originals are grossly expensive. In the states we can get a bag of 50 for less than $8 US from an industrial supplier

 

Not keeping score dude - relax -

The scary part is that the thread pitch of an M6 is kind of close - 1.25 vs 1.27mm - close enough to destroy the threads in the head, they will thread up - or seem to and just seem a little stiff, and that will be when you reach for the wrench followed soon after by a case of beer when they don't tighten as expected, if you can't thread them in all the way with your fingers do not continue .....

 

These are M6x1.0 , very coarse, as are all threads that Jaguar has screwing into the aluminum block and heads. Try your 1.0 thread gauge, you'll see it matches.

 

Well how embarrasing is that - 1.0 fits ... that's a much finer thread than I'd have expected in aluminium ... oh well dunce cap on - I'll go sit in the corner now.

Still no idea on the engine number though ....