baz walton

Hi all,
I'm just wondering if based on these specs someone could give me an idea of the safest gasket size?
The head was 137.5 with a steel saver shim @.5mm and a grpa gasket @1.3mm.

It was given a 'last' light skim when the broken cam was fixed and now measures 137mm.

I now have to bore the block to .5 and so have to buy new pistons.
The block needs to be slightly decked ( a few thou hopefully)

I will be buying marle pistons with pockets.

So, I have a head at 137 (2mm down on standard) and a decked block (say 10thou, .25mm)

I was thinking that an 80thou 2mm gasket would be ok as it is putting the 'gap' back close to where it was, but am wondering if with the pockets in the pistons it may be too much?

Any ideas?
Cheers

JFB Tech

I'd be more worried about the valve seat inserts falling out at that level of skim rather than trying to maintain the compression ratio.

R4N SS

iTrader: (6)

yep as above - i would be worried about losing a valve mate

Turbo Zetec

iTrader: (1)

20 thou isn't a light skim by any means, must have been bent like a banana or corroded badly!

depends on what you intend to do with it really. if you're looking to build a monster engine then i'd find a better head. if you're looking for something relatively normal power then you might get away with it. The seats shouldn't really cause a problem unless you're getting it very hot. I work on cylinder heads every day and can tell you that i've seen valve seats fall out of heads no matter how much they've been skimmed (sometimes they haven't at all). Other seats stay in just fine even when they're right against the head face. there's no rule to say that if the head is a little thin then they'll fall out, but it may be worth getting a machine shop to stick them in a little deeper if they think they need it. I like to have .250" deep inserts in aluminium as a rule, deeper if space allows.