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Cylinder Block Crack Repair
#1
I have done a careful assessment of a number of blocks I have had for years before building a new motor.
The majority of these are cracked between the centre stud tapped hole and the 10mm water transfer hole which is only some 6mm away.
I'd be interested to have the benefit of experience from fellow enthusiasts advising what if anything works as far as a viable repair goes and what doesn't. 
 I've prepared two drawings of the coordinates using the DRO on a mill. One of the drawings was produced from an early cylinder head and a second from an aluminium head produced by David Dye. The maximum variation is about 0.012" but there is sure a lot of clearance on the holes - 8.6mm holes for 5/16" bolts
Does anyone have a drawing showing the original cylinder stud layout?
Thanks
Jim Runciman
Perth Australia
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#2
hi jim

ive reconditioned 100s of block.

around 80% are cracked in this place. the crack can carry on toward the stud between the valves. it still doesnt cause a problem. but we have to make a desition how marketable the block is, the further the crack goes.

as long as they are not cracked to the bores.

with good blocks getting less and less, can they be thrown away.

tony.
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#3
It might be worth consulting “Metalock”. I have seen some remarkable repairs done by these people particularly in cast materials.
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#4
Thanks Peter. I didn't know that process. It is explained HERE by the way.
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#5
I agree with Tony, cracks not unusual in that position and ok to use as long as there ar no cracks going to the bore.Crack will often be seen heading toward the valves again no great cause for concern.
Definitely would NOT try to repair as you have to remove metal to do a stitch repair, you don’t have much to start with!
Cracks into the bores render the block scrap ie not repairable.
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#6
I'd only consider a stitch repair on the water jacket if the block was worth it and agree with Zeto about top cracks.
Have just checked 3 original Austin heads,All accept a 11/32" drill (8.7mm) through the stud holes so would assume Austin considered that a sensible clearance in use. Going much tighter is likely to cause more problems on removal ,CI or alum head over a long period of time.
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#7
Thanks to everyone for the comments and advice
I am familiar with the Metalock process and agree that there is not much metal to play with in this regard
Much happier now as the three rather nice blocks (apart from the subject crack) are usable. One of them has never been bored having a worn standard bore. It may cause some consternation but I am using a stepped stud arrangement to secure the head with the block being tapped 9 x 1.25mm. In the case of the inlet/exhaust manifold I have again used stepped studs 7 x 1mm into the block
Having spent a significant time in the forging industry I use 4140 rather than K1045 for studs 
One of the crankcases I was contemplating using had the starter securing bolts out to 7/16" and I wanted to open up the area and build it up but the aluminium was very difficult to weld. It would seem that we have a satisfactory job but I have yet to see if we have any distortion problems.
Again thank for taking the time to reply
Jim
Perth 
Australia
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