coop12g295 wrote:I drilled mine and tapped them 5/16 unf I think and used a long bolt and big nuts with washers to slowly pull them out
That's what I do too. Once I have the first one out, I drop a long 8 mm rod in where I removed the first one, right through the block and then knock the other one out.
I only remove the ones for the main gallery and the oil pressure relief valve. The ones for the Main Gallery are on either end of the block. When you look at the ends, you'll see 2 on each end, you can pull them all if you like. I don't bother with those on the tappet chest drain, only those towards the dissy side of the block.
For the ones for the pressure relief valve, they are much smaller. I generally use a roofing screw (these are more tensile than a self tapper) in the slide hammer. Same for the one in the cylinder head, unless it's a late one that has the pop-rivet. In that case, punch the centre in to dislodge the sealing stem, then drill the rivet head like any other rivet. Then I use the slide hammer again, but be careful not to expand the rivet any further. Also make sure you get the stem out!
When replacing them, I use 14 mm cup point grub screws for the main galleries. I use only a taper tap and thread it such that it leaves a tappered thread in the hole, but deep enough that the cup will seat on the register within the hole (you'll see that when you remove the plug. Be sure that they don't go too deep or you'll restrict the oil way to Main Bearings 1 & 3.
The ones for the oil relief valve, I use 5/16" UNF Grub Screws. Be extra careful that these don't go too deep or it will block off the relief valve passage within the block. You'll know you've done that when the oil filter explodes! No, don't ask me how I know
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Same size for the one in the head too. Again, with all these, a taper tap, leaving a tapered thread.
I think I have some pics I can put up a little later.
For sealing, I just use a thread locking grade of Loctite, but only a low strength one.
I am not a fan of replacing the plugs with the same again.