Race Engine Forum UK

Hi all,

I have heard that EDM would be the way for me to increase the bore of my MLS headgasket (as there is no standard gasket available in the size I need). My qustions are:

Is this a suitable technique?
Does anyone know where I can have this done in the UK?

I have just done a google search with little joy,

My thanks in advance as always,

N.

Hi,
What thickness are you looking at and in which material?.

Nino

Neal H wrote:Hi all,

I have heard that EDM would be the way for me to increase the bore of my MLS headgasket (as there is no standard gasket available in the size I need). My qustions are:

Is this a suitable technique?
Does anyone know where I can have this done in the UK?

I have just done a google search with little joy,

My thanks in advance as always,

N.

Hello Neal,
I have to assume you are referring to the "Wire EDM" process.

All MLS (multi-layer-steel) head gaskets I have used while made from metal layers are coated with some form of sealant. The EDM process will not cut anything with a nonconductive nature even if it is only a coating. The "Sinker EDM" process has the same limitations. I also run a tool and die shop and I employ 2 Mitsubishi FX10 wire EDM machines. I have cut bare copper gaskets on them and that worked fine.
The fully submerged wire edm process also tends to cause a buzz or flutter in the material being cut if it is thin and unsupported over a long distance. This is because along with being submerged in deionized water, the cutting zone is flushed with the water at very high pressures. This causes wire breakage and many head aches for the operator.

Another process to investigate would be water jet. The problem I can see with that is removing all of the cutting media from between the layers.

Sorry I didn't have any real good news for you.

Robert

You can't enlarge an MLS gasket if it has a crimped edge around the bore, not overmuch anyhow- and then only by using a cylindrical band (like I use for head work) because with those types it is the compression of that crimped region that generates the seal (in place of a conventional fire ring); grind it off and it won't work.

Please state the std and your oversize bore sizes here and bores of avail gaskets you know of.

GC

Thanks for all the input everyone. All interesting reading.

Standard bore is 82.5mm. Gasket size is 83.5mm. My bore 84.5mm. 1mm oversize from the gasket.

The crimped ring looks to start about 2mm from the actual bore if that helps?

Thanks,

N.

Neal, you won't have a problem with it as it stands.

Overhang of only 0.5mm on rad will be fine, provided the crown of the piston is 0.5-1mm clear of the intruding gasket. This can be assured by low comp ht on the piston (pin centre to crown dist) of putting a relief (chamfer/rad) around the piston crown.

GC

Thanks Guy and everyone else who contributed. I will take some measurements, I suspect I have about 0.5mm clearance from the piston crown at TDC.

N.