Acid-treating two blocks presently.
The 1934 one now has about 3mm clear, clean "pillars" of water channel between the cylinder jackets as viewed from the side. The early core-plugged one (with the additional brass plugs Tony mentioned were from the casting process) has been soaking and I pulled it to note that the rust seems to have gone but there are much less distinct channels between the cylinders, with more metal at the base of the cylinder jacket.
Are there distinct differences in block interiors? Clearly I can get it with a dremel, but I'd like to know what is structural and what might not be.
ok, no takers..
Well, an update. Very early block. Acid stripped beautifully, but didn't touch the agglomeration between the cylinder walls blocking the flow from side to side. So can, over time, some other sort of material reform which would be chemically inert?
I can't see how this material would have been present in the original cast, and it indeed started to shift when drilled.
One bore also perforated; I think this block was at its limit. It also brings up the issue of how much material is needed and where, for a rebore for liners? This has no cracks in the top face and still has numbers visible there. The side branch supports are also good.
Could re-linering take away ALL the duff material in the centre area of the block, creating an efficient waterflow, but just using the top and bottom of original block to affix the liner?
(17-03-2021, 09:12 AM)JonE Wrote: Could re-linering take away ALL the duff material in the centre area of the block, creating an efficient waterflow, but just using the top and bottom of original block to affix the liner?
Yes! In this case, as I said in a reply to an earlier thread about head gasket failures, the block becomes structurally weak if the bores are corroded away (the bottom face is no longer connected to the top) and the top face then distorts, leading to gasket problems. Dave Williams (Austineers) has a block, sectioned to show just this problem. So there must be enough of the original bore material left to provide structural integrity.
My own experience, over the years, is that there is more bore material in early (vintage) blocks and the material is better quality. Early blocks will usually (not always!) bore to +80 or +84 (for slipper pistons), whereas the later blocks often start to get thin.
If it’s any help Jon, I cleaned out a badly silted up block from a ‘36 two bearing motor some years @go using the old curtain spring in a drill trick, before I was aware of using chemicals.
There was no gap between the cylinders at all, I left it as it was assuming that was normal, put the engine together and used it London traffic for years, putting 60,000 on the motor without an issue.
That block was +40 at the time and I hate to admit it, was on Cords rings, again without issue!
Thanks both. So it could be that earlier ones, IF they have more material, have less efficient channels than later ones?
I'm still unsure over what would be the approach for this block now. Can structural integrity be returned through a liner being affixed solely to original material in the region of top and bottom faces, after reboring to accept?
Here's what you are up against.Corrosion behind the cylinders in particular .I doubt if chemical cleaners will get it out.
Linering a block usually means boring to around 59mm ? and inserting the sleeve. Sometimes boring may break through at some point but only in a small area so won't remove any of the built up crud outside the existing casting.You cant bore out far enough to clear it out as there would be no structural strength left in the block or be able to seal the water jacket either.
HI Jon,
The short Answer is No unless you weld the liner top and bottom,
You have to remember that the liner is pressed in to give a Guaranteed thickness for the piston to operate in and bring the bore back to standard, and will not provide any strength for the Block.
Hope that makes sense
17-03-2021, 01:04 PM (This post was last modified: 17-03-2021, 01:09 PM by Robert Leigh.)
Changing the subject to another item in the picture, where can I obtain an oil filler mounting like that,please?
Where I have found solid rust blocking the channel between bores I have carved through it with a hacksaw blade. As you do this it is quite easy to sense the difference between cutting the casting and just cutting the rust, which is all I wanted to do.
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17-03-2021, 09:13 PM (This post was last modified: 18-03-2021, 12:23 PM by Greig Smith.)
Plus 2 for the hacksaw blade approach - that & a length of curtain rod spiral wound cable which I ran at fast speed in my battery hand drill, this tended to find its own way into nooks & crannies. I didn't get a lot more crud out, but definitely shifted some in the corners
Short lengths of curtain rod spiral wound cable & paraffin work wonders to remove crud from crankshaft oil holes. Slow speed on the electric drill & back & forth from all ends. Finish with a good flush of paraffin & compressed air. Top Tip - do this over several layers of newspaper, you would be amazed at what comes out of so-called "clean cranks'
