Lambda block repair.

[davidwheeler]

Autumn 2023 I took Shela (the VIIth torpedo) to the local Agricultural show where she developed a sever water leak into a cylinder.   Investigation showed the the third head stud had pulled the land of the block up as it had broken away with corrosion.      There was also a crack in the front right corner which extended through the stud hole.   After I had cleared out all the corrosion the block looked like the picture.     I took it to my good friend Nick Gilfillan at Cold Metal Spray for rebuild.
We collected it last week.      All the rot has been replaced by solid metal and the crack has been pinned as well.   Helicoils in all the stud holes.   Vacuum impregnatiopn x2.     
It took a very long tame as it was fitted in between other (highly technical) jobs and cast a great deal of money because it too a long time but it has been, essentiall, rescued from scrap.
Nick will take on other such work if needed,     This is not the first of my engines he has treated either.
https://www.coldmetalspray.co.uk/

[davidwheeler]

Freyja and I started the rebuild of this engine today.
Fitting the pistons went OK apart from No 1 which would not rotate far enough in the bore to get the gudgeon pin hole lined up at right angles so as to be able to insert the pin until I took a micron or two off the piston skirt.     Fortunately getting the piston rings in is comparatively easy because of the oblique angle of the head surface.
After lunch we fitted the crank, first winding in the retaining (Screws, pillars posts?  Cannot think of the right word).    Not all of them went in fully.     Put in the crankshaft and fitted the bearings thereunto to find it locked solid.    I was sure of the positioning of the outer ones but not of the middle so we took off the bearing caps again and removed the posts (otherwise the caps would not come off!) and experimented with the block side centre shell until the crank would rotate.  We then fitted the outer two caps and the crank still rotated.   Tried the 4 possible computations of centre shell and cap until the crank rotated still.   
Next to the posts not going home.  I looked out my Whitworth taps and found the right one (Vincenzo used Whitworth thread because it was designed by an engineer not a committee and only metricised the outer facets of the nuts).   In it went to come out again coated with grey powder - it would seem that vacuum inpregnation leaves deposits in holes.
That was enough for one day, I shall clean out the other holes and install the posts and then wait for Freyja before continuing.   It is necessary to pass on The Knowledge to the next generation.

[davidwheeler]

Still having difficulty with the posts.    I am retapping the holes to a greater depth needing to start with a taper tap before the parallell one even though there is more depth to the hole than is needed.     Also, the crank is very tight which should not be as I have not done anything to the shells or mains.   I wonder if there is a deposit of vacuum resin also in the shell housings in the block.   Has anyone any experience of this?

[chriswgawne]

I have had trouble in the past with an Aurelia B21 block which the previous owner ( a well known restorer) had vapour blasted. The cam followers were very sticky ( which I discovered somewhat late in the day!) in the block and I ended up having to disassemble the engine and ream the holes out. What a pain!
Chris 

[davidwheeler]

Sounds about right!   I am very carefully cleaning the housings with emery paper.     The amount of crap I got out of the studholes was remarkeable and, also, a pain.
My other Lambda block is in for similar treatment and I have alerted Nick Gilligan who is overseeing the work.

[lancialulu]

Vapour blasting is great for open surfaces but threaded blind holes (particularly helicoiled threads) need extensive hand cleaning as the media just moves  about in the hole. It is a PAIN!