Headgasket change - deck head?

[JH32]

Hi

A mate of mine just let me know that I should get the head planed/decked when I'm changing the head gasket. Is this totally necessary ?

It's an RB26, and I'm replacing the gaskets with a Tomei gasket kit (metal headgasket).

[proengines]

It is necessary. metal head gaskets require a very low Ra (roughness average) finish to seal properly as there is very little give in the gasket to conform to the head. The head also needs to be dead flat. Most machine shops use PCD cutters in their surface mills now to get the finish fine enough to seal properly with these gaskets. Makes sure the block is spotless as well. It doesnt hurt to use an oil stone to finish the block to remove any small high spots, you find the block does pull up a little around the head bolt holes.

It should cost less that $100 to have it machined as long as you remove the manifolds and cams/buckets/shims. Make sure you keep the buckets and shims in order so you can put them back on the same valve.

[Boosting]

any one know how much is usualy cost to get the head rebuilt with valves and so forth

[JH32]

Thanks very much for that Greg

Apparently the hard bit is putting it all back together again!

I think I'll let them do the lot as I don't want to do anything wrong there!

[pnblight]

Tuff Question if the head is flat no

But it's hard to know this for sure so it comes down to who you are willing to trust with your pride and joy to check (normally the head should be flat unless it seen series heat)

pete

[JH32]

This engine was totally stock when I pulled it apart, so don't think it's seen massive boost and all that sort of thing.

How can I tell if it's perfect flat, as to be honest I don't really want to have to go to the huge trouble (and cost!) of having the whole head pulled apart and reassembled!

[pnblight]

Can you access to a really straight edge adge and feeler gauges

if so lay the straight edge accross the head or block and see if the feeler gauge ( 1 or 2 thou) will go under the straight edge anywhere on the head

simple really

pete