Cometic MLS head gaskets

[230ina245]

Hi everyone
I'm interested in hearing the experiences of any members who have used said gaskets.
In particular, if anyone with a B200 has used them.
Reason being that I want one for my B200, however the ones I have seen have a 92mm diameter hole, whereas the combustion chamber is 94mm & the cylinder 90mm (measurements rounded to nearest mm). This means a 1mm portion of the gasket will be in the combustion chamber. Has this made a difference to anyone using them? Think the volvo gaskets are 94 or 95mm.
Wondering if it's worth the faff of getting a 94mm diameter one made.
Tim

[Laird Scooby]

Why do you want or think you need an MLS gasket? Red-blocks don't normally need black magic like that, especially on the B200.

[Stephen Edwin]

You could try for example http://www.ferriday.co.uk/mls-head-gaskets/ to have the Cometic gasket modified.

I just found them by an internet search. That's all I can say.

[230ina245]

Hi Dave
Going for a cylinder head with tight squish. The cometic gaskets are produced with a range of known compressed thicknesses thus allowing for an accurate squish calculation to be made.
Er, also what do you mean when you say "especially on the B200".
Stephen - thanks for the link - useful to know. As I haven't ordered a gasket yet I should be able to get the right size from Cometic - once I've worked out what the right size is! I've read somewhere that they make them to order. The size I'm thinking of has already been made (& on their database) but not in the thickness I need.
Tim

[Laird Scooby]

Originally Posted by 230ina245

Hi Dave
Going for a cylinder head with tight squish. The cometic gaskets are produced with a range of known compressed thicknesses thus allowing for an accurate squish calculation to be made.
Er, also what do you mean when you say "especially on the B200".
Stephen - thanks for the link - useful to know. As I haven't ordered a gasket yet I should be able to get the right size from Cometic - once I've worked out what the right size is! I've read somewhere that they make them to order. The size I'm thinking of has already been made (& on their database) but not in the thickness I need.
Tim

The B200 isn't a particularly powerful unit, therefore it's fairly low-stressed Tim. As such, the normal head gasket is usually more than up to the job of maintaining a seal as long as the usual basics are all good.

What is your thinking about a tight squish? Are you trying to get it to run leaner or something along those lines?

[230ina245]

Ahh - I see what you mean.
Unfortunately I am going in the opposite direction of running lean - higher boost & higher compression. Should raise its stress levels a bit! Lean running is definately not on the cards.
I have found that the normal head gasket gives up sooner or later at about 25 psi. I decided to start from scratch & try to build an engine combo to take this in it's stride.
Tim

[Laird Scooby]

Originally Posted by 230ina245

Ahh - I see what you mean.
Unfortunately I am going in the opposite direction of running lean - higher boost & higher compression. Should raise its stress levels a bit! Lean running is definately not on the cards.
I have found that the normal head gasket gives up sooner or later at about 25 psi. I decided to start from scratch & try to build an engine combo to take this in it's stride.
Tim

While you've got the engine in bits then Tim, make sure you get the oil and coolant channels very clear in the region of #4 pot, i've heard B200s are prone to piston slap on #4 due to either poor cooling, poor oil supply or a combination of both.

Just out of interest, are you converting it to LPG at the same time? Although pretty new on the market, Liquid Phase LPG injection kits are available here now abd that would give you a couple of advantages - first, charge-cooling and second, would help cool the pistons and head, allowing you to run higher boost plus the LPG is about 105 octane so is less likely to cause detonation too.

[230ina245]

Yes - I was going to do the "group A" hole mods to the head. I'd heard about the poor cooling - on the 240 the heater takes coolant from the back of the head and it returns to the pump. When the heater is switched off no coolant flows.
I was thinking of rigging up a diverter valve which would allow coolant to the heater & switching the heater off would divert coolant back to the pump. I've even seen the heater outlet on the head used to take coolant forwards to a fitting fixed in the thermostat housing.
I had not considered using LPG - had a bit of a look to see if it could be used in a similar way to NOS or water/meth injection but it seems to only be used instead of petrol altogether. I am too far down the route I am taking to make such a drastic change. Still looking into possiblities though as I have been planning on using water/methanol injection as part of the setup.
Tim

[barkster1971]

If you want a high power motor a b230fk is a much much better starting point.
The bore allows bigger valves and flows better. You'll be spending money on a lesser end product. You'll have to skim the head and deck the block to run a cometic gasket anyway. It's all been done before and nobody uses a b200 block.

[classicswede]

The Cometic gaskets can be tricky to get a good seal on. You MUST have both the head AND the block surfaced perfectly flat to get a lasting seal.

Below 500BHP I would not even consider one and there are lots of engines out there in the 6-700 region still using a standard gasket.

With the B200 I would be more tempted to machine the raised crown of the pistons and just throw more boost at it, maybe go long stoke