I don't know if it needs line boring. It seems wise to check the tunnel alignment before carrying out other operations. I understand most blocks are alright in this area.
I would like to ensure there is sufficient crush on the bearing shells too. I don't have accurate enough measuring equipment to check whether the tunnel bores are on size so will need a shop to check this too.
I stripped this engine thinking I'd just get it rebored as the bores are scored and it's using oil - sort of a patch up job.
Of course now it's stripped it needs cam bearings and the crank sorting. I need to try measuring the crank journals but I don't think it'll be accurate enough either. The journals look alright but the shells are quite scuffed.
I'm confused about how you sort out the crank thrust washers. There's 0.007" endfloat and a proper mixture of what look like different make thrust washers measuring 0.0925" and 0.0930" on the front side and 0.0940" and 0.0955" on the flywheel side. I've read somewhere that standard thickness is 0.0930". How do I sort this mess out?
Also, the centre main cap is a little loose on the dowels which I don't like.
Thanks for the book recommendation, I'll check it out.
All parts of the block need to be checked prior to spending money on it. I do give mine a preliminary check over, just to see that it's not a basket case, then have them chemically cleaned and a much more thorough check out before machining. It does take me a couple of hours to check everything and not something that can be rushed.
In specific regards to the Mains tunnels, there was two ways they machined them in the factory, depending on the particular era the block was made, in the early days they were essentially line bored, later around 86-ish (maybe a little earlier), they were line bored (by a similar method) then Line-hone finished. It's rare they'll be out of alignment but usually rectification is only needed as mentioned above.
Yes, your centre main does need looking in to, though, usually, it's from chaffed dowels. All the Caps need to be checked. As a matter of course in a build, I always replace the dowels. I note that Swiftune have 'hardened' dowels. I would recommend against these as the bolt is what holds the Cap in place, the Dowel is only for alignment until those bolts are torqued down. Fitting hard dowels is only asking for issues with the Block and Caps that will lead to the necessity for a Line Bore.
'Patch-up jobs' on engines or 're-ringing' them. My own view on doing this type of an over-haul is that it's a waste of time and money. Looking at the fresh or re-honed bores and new rings, in order to get them to bed in and seal, so that performance is resorted and oil consumption comes back to something that's acceptable, the Con Rods need to be checked for alignment and corrected. Also, the Bearings need to be replaced, as these are what controls how much oil is splashed up on the bores. With worn bearings, at low engine RPMs, the bores tend to run dry, while at medium and higher revs, they become saturated with oil, often overcoming what the control, rings can cope with, so, the bearings should always be replaced. Before fitting them, the crank journals need to be check for similar reasons as well as making sure that there's not too much going through the Mains, to be sure there's enough getting to the Big Ends.
Likewise, the Head also needs to be overhauled, to ensure excessive oil isn't coming through the guides and that the valves are sealing in order to make proper cylinder pressures, to get the rings to bed in and not glaze over.
As combustion & breathing is going to be better than it was before, fuel and ignition requirements become more critical, so the Carb and Distributor should also be overhauled.
So, you can see here, that one thing does lead to another and has a direct connection. There is no 'short cuts'.
When I do an overhaul, everything is done from the Air Filter and Oil Filler Cap, through to the Sump Plug, Pot Joints, Radiator Cap, to the Clevis Pin Split Pin on the Clutch Arm. Not to be 'pedantic' but, just from my own understanding, what's needed and necessary. Also, when done like this, they really are like new (or better) and if looked after, will go on to give a very long and trouble free life.
Measuring Crank Journals really does need a Crankshaft Micrometer. These have a longer Back Anvil so you can get right in to all parts of the Journals without the Webs getting in the way. You can try with an ordinary Mic. but you're only going to be able to measure a liitle either side of the centre of the journals and not at every angle.
In regards to sorting the Crank Thrusts, ideally, have the Crank Serviced, then assemble it up in the Block with a set of Stock Thrusts, measure the End Float then if outside of acceptable limits, depending on what you are measuring in terms of Float, you can get over size thrusts or if needed, have an over-size set ground to suit. This is a normal reconditioning operation and with the A Series, we are lucky that our Thrusts are not integral with one of the Main Bearings like many other engines are.
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