Composite head gasket RV8 3.5

[martin_t]

Hi
Can someone explain the benfits of a composite head gasket to me please? I currently have my heads (standard sd1) in the machine shop being renovated and having new guides valves and springs put in. Do I need to have them skimmed as well? Do I need to skim the block faces (as I have read somewhere on the site)?

Thanks

Martin

[TINKA]

The tin gaskets are very prone to leaking and so they started to use the composite ones as they are of a far better quality and more reliable. If you do go the composite route you will need to have the block skimmed as otherwise you will drop your compression ratio as the composite gaskets are thicker. If you use the search feature you should be able to find all the info you need. HTH

[martin_t]

Originally Posted by TINKA

The tin gaskets are very prone to leaking and so they started to use the composite ones as they are of a far better quality and more reliable. If you do go the composite route you will need to have the block skimmed as otherwise you will drop your compression ratio as the composite gaskets are thicker. If you use the search feature you should be able to find all the info you need. HTH

Thanks for that

Regards

Martin

[martin_t]

Originally Posted by TINKA

The tin gaskets are very prone to leaking and so they started to use the composite ones as they are of a far better quality and more reliable. If you do go the composite route you will need to have the block skimmed as otherwise you will drop your compression ratio as the composite gaskets are thicker. If you use the search feature you should be able to find all the info you need. HTH

Just one thing...

Is it just the block that needs skimming and not the heads? What needs taking off the block?

Thanks

Martin

[RichardG]

As an aside the lifter pre-load also gets mucked up if you don't have the heads skimmed.

[russell_ram]

DO NOT skim the block (unless it's only a lick to clean it up).

You should make the change to the heads (as the factory did). Your heads will then be transferable to any other block should you decide to 'upgrade' later. You need to take of 27thou to maintain original compression ratio and alignment of intake ports to manifold. You would be foolish not to make the change if your heads are already in the machine shop. The composite gaskets ARE measurably better at sealing both the combustion chambers and oil and water galleries.

No need to change to 'stretch' bolts either unless you're buying new anyway. You can use your old style bolots and torque as per the tin gasket settings. You WILL need to re-torque once after 1/2 hour or so AND after first run though as the gasket will relax. If you use new stretch bolts and use the torque+ angle tightening regime then you will remove the need to re-torque.

HTH

Russ

[martin_t]

Originally Posted by RichardG

As an aside the lifter pre-load also gets mucked up if you don't have the heads skimmed.

now I am confused!!

I thought If I just put the composite gasket on without doing anything all I would lose is a bit of CR? Maybe I should just stick to the tin one?

Regards

Martin

[jeff]

Hi Martin,

I ruined a good engine when the tin gasket allowed coolant to leak and corrode the pistons and bores.

Russ really knows what he is talking about, have the 27 thou skimmed from your heads and fit the composite gasket, also use a composite manifold gasket.

jeff

[martin_t]

Originally Posted by russell_ram

DO NOT skim the block (unless it's only a lick to clean it up).

You should make the change to the heads (as the factory did). Your heads will then be transferable to any other block should you decide to 'upgrade' later. You need to take of 27thou to maintain original compression ratio and alignment of intake ports to manifold. You would be foolish not to make the change if your heads are already in the machine shop. The composite gaskets ARE measurably better at sealing both the combustion chambers and oil and water galleries.

No need to change to 'stretch' bolts either unless you're buying new anyway. You can use your old style bolots and torque as per the tin gasket settings. You WILL need to re-torque once after 1/2 hour or so AND after first run though as the gasket will relax. If you use new stretch bolts and use the torque+ angle tightening regime then you will remove the need to re-torque.

HTH


Russ

Thanks Russ

The heads are still in the machine shop at the mo. Will go there tomorrow and get them to take 27thou off while they are in there.
Thanks for the information on this and everything else, its a steep learning curve for me, but I'm enjoying it!!

Many thank

Martin