Hi all, just after a bit of advice. I am looking at changing the headgaskets on my 1999 version 5 sti type ra v-limited and i want to use cosworth gaskets but unsure as to which thickness i need to purchase. Any advice would be very much appreciated.

 

why change them? has previous one failed? if so look at sorting out the crank bearings as well or you could find they fail very soon after the rebuild

 

As above.

Different thickness gaskets are used to even out differences in head and block thicknesses, so that if you have, say 10 thou skimmed off both, use gaskets TWENTY thou thicker than normal. This will keep the compression ratio the same, which is important.

And yes, DO think about splitting the block and fitting new bearings, they often go soon after the headgaskets have been changed.

 

Hi the reason i am taking my engine apart is because i have bought a version 5 sti type ra v-limited and it has dyno print outs of 341bhp and the lad i bought it from had given me receipts for a forged engine with roger clark omega pistons and me being me wanted to be 100% sure it was what he said it was and he was right so now time to put it back together the headgaskets i removed have these number's on the passengerside had 610002801 483 and the drivers side had 608003801 483. i think they are standard subaru items but not sure but would like to replace them with cosworth gaskets anyway. any help please guys?

 

Don't use thicker gaskets unless you have had heads, blocks, or both, skimmed.

TBH, at those power levels, standard Scoob gaskets are good enough.

 

As he said