I am rebuilding my XJR and looked at different sources for head bolts
The Jaguar Head bolts at parts geek.com (W0133-1786520) $14.25 ea
The Lincoln Head bolts at parts geek.com (5628-07075745) 34.25 set
Made by FEL-PRO
Do any of the techs on the forum have any input on if these bolts are OK to use?

The only difference I see is that the unthreaded section of the Jaguar bolts is slightly larger(.387" vs 0.350") but the Jaguar bolt is necked down to 0.350"
before the threads

 

The Lincoln bolt is probably a rolled thread while the Jag is a cut thread, and much stronger due to the larger dia. Have you checked Range Rover bolts. Someone on one of the forums found them equivalent to the Jag at a much lower price.

 

Hi RJ both bolts are rolled, notice the jag bolt is necked down to the same core thread roll diameter (0.350")

 

Yes, I missed that. I hope one of the Techs will be able to help.

 

The two things I would be wondering about are:

-- clearance for the higher bolt head

-- whether the larger shank is required for lateral location

 

Plenty of room for the heads with washers, head is located with 2 steel rings on top outer edges of the head.

My concern is the elevated head pressure from a S/C application, but 2 bolts of the same material are only as strong as the smallest diameter. I think I will call FELPRO direct.

 

If you compare the OE Jag bolt to any one of the originals removed from the engine, you'll notice an ever so slightly longer bolt in the used one...

The OE Jag bolt has the decrease in diameter to promote necking or the stretching of the bolt in this area only. No such thing on the other one. This is why I bang on about factory torque angles. That's why they're expensive.

OE bolts all day for me. I've mentioned SC Range Rover head bolts do the job at a fraction of the cost, but apparently there's no saving on them in the USA...