Hey Gents,

Looking for a stout head gasket set for my XJR. I heard they cross with the ford 4.6l gasket. any validity to that? Or does anyone make performance gaskets for these cars? Thanks.

 

So BI doesn't know, and let you ask

Don't know what they do with the Fords, but you can contact Cometic, they make custom head gaskets for our cars, i.e. MLS in different thicknesses.

 

O.E.M are pukka composite, I'd use them. If you really want the heads safe, use new head bolts.

 

BIP has got it covered. Trust me. It's a custom piece. I was simply wondering out of my own curiosity if the is any company producing them.

 

Considering the contest that is yet to be resolved, answering is a generous gesture.

Should be worth a +10 horsepower handicap credit

 

lol! Nice Idea. But as I said BIP has designed a custom gasket for the XJR and it's stout alright. I guess im just frusterated at the lack of aftermarket parts out there.

 

All depends a bit on what you want, the MLS ones available are doing their job. But if you want to go for very high boost pressures (higher octane fuel regions) and stock compression or lowering the compression via a thicker headgasket, then I am not sure, but there is tons of info about this.

 

Since this is a completely custom application, you could consider converting to head studs in the highest grade and finest thread that you can find. And, ground washers.

Mount them in a test jig, or junk block. Consult the fastener manufacturer for torque angle and fastener stretch suggestions, apply to test fasteners and see how much lee way there is by testing to failure. And then, go as far as you dare on the real deal.

 

I'd suggest ARP bolts, they're the best. If McLaren F1 use them........

@ Avos, what did you pay for the Cometic gaskets? and where did you locate them? cheers!

 

@Sean,
You can contact Cometic directly, here are the partnos: C4376 & C4377
They are the same for the 4.0 as the 4.2 engines. The only difference is the thickness, i.e. 0.030" for the 4.2 and 0.050" for the 4.0 (but a 0.040” would also be a choice imo, as long as you are not going to extreme boost levels). Also mention the diameter cylinder diameter when ordering, i.e. 87mm.


I chose actually not to go for the ARP bolts, not that I have any doubt that these are better, but the disadvantage is that you can’t get the heads of anymore in situ. As I am not racing my car, nor go for extreme boost levels, I expect the stock stretch bolts to do the job, and so far they have done.