Well just because i figured Ive been this far already i might as well install the cutting ring gasket from VAC Motorsports.
Basically its nice and easy install, but a word of caution!
DO NOT INSTALL THIS HEADGASKET WITH THE ENGINE IN THE CAR!
I say this because i did it, the first cutting ring slid just enough as we put the head on that when i put coolant back into the cooling system it entered the sump and putting coolant all over the entire running assembly. Please! Pull the block and do it on a flat surface! This gasket has barely any tolerance so it needs to be done right!
So first stop is ensure the block surface is clean, either have a shop machine it or use 800 Grit sandpaper wrapped around a piece of straight glass or steel, for example Keystone, lathe tooling, engineering bench surfaces, straight edges. Must be exactly true straight or your block is going to hate you!
I used a lathe cutting tool roughly 30cmx15cmx15cm
Cover the pistons and timing case, i used rags/old bits of clothing, and shoved them into the bores and timing case, down enough that they didn't interfere with the sanding, last thing you want is aluminium in your piston bores.
Apply some cutting lube, i used WD40 & Using the paper do figure 8s and continue until any dead bits of gasket & carbon are gone and the block is shiny, if you go up and down or left and right you leave grooves for the coolant or oil to escape and you'll blow a gasket.
Give the block a really good clean, blow out cylinders really ensure they're free from debris, use brake cleaner to clean the block surface from leftover grit from sanding use cloths that don't leave fibres as these will prevent a good gasket seal! (I would also suggest doing an oil change after you've reach operating oil temp)
Ensure your head has been machined, not kidding this is a must! Also clean the surface with brake clean and wipe down with a cloth that doesn't leave fibres, give everything a good blow with compressed air both head and block ensure its all debris free and proceed to laying the gasket onto the block! Aligning the rings to the gasket and bores, we ensured both alignment dowels were in the block (factory one is in block and one is in head) we did this to ensure the gasket was absolutely perfectly aligned.
In the picture below, you need to use RTV, i used oil resistant 250° C RTV to apply some sort of sealing layer around this low pressure oil gallery (circled in red) as for some unknown reason the gasket doesn't have it whilst the stock one does, i have emailed VAC about this. Apply it in a thin bead on the block and the top side of the head gasket as you want to seal between the gasket and block and gasket and the head, i say thin because too much and the gasket wont properly seal everywhere else.
Next place your head studs in if you have them, slide your head on and torque it up to 95ftlbs in 3 stages. If you're using the factory head studs just align to the dowels and put new studs in following BMW's spec.
BE EXTREMELY CAREFUL PLACING THE HEAD ON THE GASKET AS THESE RINGS CANNOT MOVE IF THEY DO THEY CAUSE EITHER HOTSPOTS IN THE CYLINDER OR THEY'LL HOLD UP THE HEAD GASKET CAUSING COOLANT AND OIL MIXING
This gasket cuts grooves into the cylinder head approx. 6thou in depth, head will need to be machined if you blow this gasket, also if you're using arp headstuds -- which you should be for this gasket, warm the car up to operating temp (oil temp of 85°C not water temp because thats subjective. Then turn off engine and remove valve cover and check the torque of your head studs again. If you're using factory head bolts Goodluck you can't check these, just hope for the best.
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You should be able to just see the black RTV, i added extra than mentioned above due to my enlarged bolt holes for my unique stud setup that would not be required if i had the n55 studs to begin with.
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