Head Gaskets / Compression / Power ?

[f@-pots]

Hi Guys, I was having a chat at the car wash 'as you do' to a fellow Chim owner who was talking about 'this mate of his' who was told by TVR Power that some head gaskets on the market , which are thicker, can reduce compression to the tune of approx 30 BHP !! Having just done a 'head job' on mine which included fitting composite gaskets I was concerned that I had unwittingly 'neutered' my P&J ! Mines 4.0 serp . Please tell me that i'm not guilty!!

Nick..........

[350Matt]

All depends on what gasket was there to start with.

The std rover tin ones I think are 0.4 thick and the composites are 1.0mm thick so if you had tins on before and fitted composites then yes you'll lose compression.
you have to machine the heads to compensate.

Matt

[spend]

Even the pre-serps (14bolt heads) were skimmed & fitted with composites AFIK.... but I've never been ursed to look at 4.0 :bigsnob: Maybe you should have measured the components that you replace to ensure compatibility time consuming but necessary with these engines, as well as occasionally discovering an alternative to free a few more ponies.

[That Daddy]

I thought the serp motors had the composite gaskets standard(please feel free to correct if wrong)i would not piss about with cheaper brands just fit the Elring factory gaskets(yes you can see the quality)sourced easily,i plan on lifting the heads on mine in the spring new double springs porting valves ARP studs kit etc so have brushed up on this one already i have been quoted just under £100 for a complete Elring headset,or you can get just the headgaskets for £30 approx.

Edited by That Daddy on Wednesday 7th January 14:03

[spend]

[quote=That Daddy..the Elring factory gaskets sourced easily...
[/quote]
Official LR ones that is? You may find some TVR's with ringed heads and comp gaskets with copper fire rings, YOU WILL NEVER be 100% sure until you dismantle IMHO. Even then deducing what is original and what may have been butchered in at some service stage is not always easy

[f@-pots]

Well it was composite out and composite in , (plus bought from TVR supplies I think) so unless there are a multitude of composite gaskets there of varying thicknesses (try saying that with your teeth out !)I reckon I'm safe--ish ? I think I'd have noticed if the new gasket was appreciably thicker than the one I took out plus with it being a 1999 you're probably right in saying it would have originally have had a composite gasket fitted. OK I've convinced myself that no harms done and all is well in my little world.

Ta to all, Nick....................

[450Nick]

Either way, 30 horsepower for .3mm is surely exaggerating things a bit?

[rev-erend]

450Nick said:

Either way, 30 horsepower for .3mm is surely exaggerating things a bit?

That's pub talk that

[rev-erend]

350Matt said:

All depends on what gasket was there to start with.

The std rover tin ones I think are 0.4 thick and the composites are 1.0mm thick so if you had tins on before and fitted composites then yes you'll lose compression.
you have to machine the heads to compensate.

Matt

I've had both and can confirm those thicknesses...

[That Daddy]

f@-pots said:

Well it was composite out and composite in , (plus bought from TVR supplies I think) so unless there are a multitude of composite gaskets there of varying thicknesses (try saying that with your teeth out !)I reckon I'm safe--ish ? I think I'd have noticed if the new gasket was appreciably thicker than the one I took out plus with it being a 1999 you're probably right in saying it would have originally have had a composite gasket fitted. OK I've convinced myself that no harms done and all is well in my little world.

Ta to all, Nick....................

Yep,i would say your safe

[mb450]

That's exactly what I did on my 1999 450. Composites out, new composites when it came to putting it all back together.