steel or composite??

[brettv]

Hi,replaceing the headgaskets on my 3.9 v8 discovery 1,i was given the choice between steel and composite,anyone got any opinions on the pros and cons of each?is one better than the other?any help would be greatly appreciated.:confused:Its a 96 model with 100000 klms on it,thought it had a blown manifold gasket but on closer inspection discovered it was chuffing out the headgasket.

[MacMan]

What's the vintage of the V8? My 93 3.9 was the first of the 4 belt 3.9s fitted to Disco's and was fitted with the tin gaskets at the factory. In 1994 the 3.9s went to a serpentine belt configuration and someone will be able to confirm this but I suspect they went to composite gaskets.

I was rebuilding with 9.35:1 high comp pistons along with a block deck and head skim, so I wanted maximum compression ratio retained. The composite gaskets are thicker and would have counteracted some of the work done. The mating surfaces are critical with the tin gaskets as is clamping force, so if there's any doubt on the surface integrity then the tin gaskets will be more of a gamble. Also, I used Payen gaskets which are reputedly the OEM suppliers for Rover. There are cheaper replacements, but considering the work required to deal with another failure I spent the extra money for Payen even through the VRS kit I had included two gaskets. I treated mine with Hylomar spray and refitted the heads with ARP studs.

https://www.aulro.com/afvb/images/imported/2012/10/386.jpg

[clubagreenie]

Can agree on one thing. Use the ARP studs, please.

[brettv]

thanks for responding to my post,one more question,these arp studs ,why are they better than the stock head bolts and where do u get them?excuse my ignorance.

[Blknight.aus]

they tend to be reusable and offer better quality control than the bolts.

Additionally..

the studs are in place on the gasket then the head and you dont have to worry about the head and gasket being misaligned

because you're not turning the steel thread in the ally block when you tighten down theres a lot less risk of galling which prevents bad torquing and lessens the chance of thread stripping.

IMHO...

if you're not going for power mods just overhaul work the composite gaskets and bolts are fine providing everything came apart cleanly and correctly.

minor power upgrades or if there is any doubt then the studs are worth the money.

more serious power upgrades and then the tin gaskets and good gasket coatings become required and if youre into this region of speculation about what your about to do and dont know why that is... you might want to stop and have a think about if you should be doing it or paying someone else to.

[clubagreenie]

The bolts are a TTY (Torque to Yield) design, so they allegedly stretch a certain amount when tensioned. Experience through testing both Rover and Toyota bolts has them far from adequate. Plus there's the thread issues.