What are these composite gaskets?

#1
What are the best fitment option as far as V8 head gaskets go? I've seen a lot mentioned about the composite gaskets being better for sealing over the standard (tin) gaskets (as well as being a bit thicker) and I was enquiring with a company (here in OZ) who do a VRS Gasket Kit and say's that their gaskets are graphite type (graphite coating presumably similar to industry flange gaskets). Anyone know if these are worthwhile purchasing? or are these the composite type? And what gasket sealing compound is best to use, I've used blue hylomar in the past (on cyl heads) and normally use Loctite Master Gasket (dark red) on my normal joint gaskets and they say it's very good for head use but have not used it for such (yet). look forward to your thoughts,

Regards,
 

harveyp6

Well-Known Member
#2
I've never used sealant of any kind on either tin or composite head gaskets. The composite ones have the advantage of reducing the c.r. by about 0.6. because of their thickness, and need to be used with a matching composite inlet manifold gasket.

I have no knowledge of the particular make of gaskets you mentioned.
 

SydneyRoverP6B

Well-Known Member
Staff member
#3
Hello Scott,

Rover introduced the composite head gaskets for the Rover V8 with the introduction of the 4.0 and 4.6 litre engines. These engines were fitted with an all new head design, which featured 28cc combustion chambers for specific use with composite gaskets, and 10 bolt head retention.

Cylinder heads made prior to 1994 all feature 36cc combustion chambers and 14 bolt head retention. These heads were designed to be used with pressed metal gaskets.

You can of course use composite gaskets with the 14 bolt heads, but the CR is reduced as the gasket is thicker than the pressed metal ones, for which these heads were designed to be used. As harveyp6 mentioned, using composite head gaskets with 14 bolt heads will also requre the use of a composite inlet manifold gasket.

Composite gaskets provide improved sealing when compared to the pressed metal design. I don't know about the graphite head gaskets Scott, but I would assume that they too are of a fibrous nature like the composite ones. If you go to the local Range Rover spare parts store, they will have the Rover composite gaskets.

Rover are very specific about NOT using any sealant on cylinder head gaskets. This applies equally if using pressed metal or composite gaskets.

Rover also ammended the torque settings applicable to the cylinder head bolts on 14 bolt heads. (Ref....1997 Land Rover Engine overhaul manual covering 3.5, 3.9, 4.0, 4.2, 4.6 litre engines.) Specifically, when using pressed metal gaskets, the outer row of bolts..numbers 11 to 14 the torque for these bolts is reduced to 44 lbs/ft where as for all others the torque is 66 lbs/ft. If using composite gaskets with 14 bolt heads, then these torque settings will also apply.

Ron.
 
#4
Thanks for that chaps, very interesting, I think I might go and get the gasket set I mentioned earlier as i'm in the process of replacing a timing chain and sprocket set and I'll be needing oil seals etc anyway. Useful to know about the cc of the combustion chambers because when I had the head skimmed on a Triumph 1850 the engine always ran on after turning off which I was told was because of increaced c.r due to skimming and not (at the same time) having the combustion chambers cc'd back to standard, so am I thinking it is best to also re cc V8's as well if also having heads skimmed. I'll update this post after I find out what the cyl head gaskets are like. I know my dad (years ago) put a good smear of nickel antisieze on his 2000 head gasket without any detriment.

Regards,
 
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