Block Front Fixing Lug Broken

[Chris KC]

Can anyone suggest the best way to go about repairing a broken block fixing lug please? 
Given an otherwise OK block and need to keep cost realistic; it would be for a touring engine, nothing exotic.

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[Ian Williams]

You could put an additional lug on the end of the valve chest as one would do when building a sprint/race engine. The damaged lug would then not take any real strain and with a self locking nut fitted to the stud it would probably work happily in a touring engine. I guess the lug could be repaired by an extremely competent welder but the risk of introducing brittleness is probably quite high, others may have further comments on this as it is not an area of my expertise.

[Ray White]

I would take it to a cast iron stitching specialist.  I have used a firm in Burton on Trent and was more than little impressed with what they could do with cast iron.

[Chris KC]

Thanks Ian, must say I hadn't thought of that.
Agree, welding carries some risk and likely to cost if done by a pro.

I think Ray the same goes for stitching - it can achieve remarkable results but not for the 50-odd quid which would get me another block. It's one I haven't spent any money on as yet.

I have another block which was (I think) bronze welded in this area, I confess I'm not 100% sure what that is (sounds rather like brazing), but then the nature of the break was also somewhat different.

[Bob Culver]

Is there a crack running into the bore? If not seems useable as is. Could a filler piece be file up and fill the gap and shre the load sufficent to avoid the stud tending to tilt? With many old blocks ould be the least of concerns.

[circeonya@hotmail.com]

Do I see a crack running across to the bore? If not, what about fashioning a bit of scrap cast iron ifor the gap and securing with JB Weld?
JB Weld is incredible stuff, but the quick set version is not in the same street.

[Chris KC]

Most of the lug is still there and there is no visible crack - it's basically just 'chipped'.
I'm inclined to agree Bob, most of the strength is still there, it's just a question of arranging some suitable in-fill to seat the nut properly.

Not knocking epoxy adhesives for one second but in such a case I feel the reinstatement of metal is required.

I'm afraid my knowledge of metal joining techniques (brazing, welding, soldering etc) is not enough. Time to consult a pro perhaps. Seems a shame to toss a block for what seems quite minor damage.

[JonE]

why does it need to join? Bob's point of a "filler" at the same height in a similar material... that would just stop the tightening up stay horizontal - seemed sensible. A small metal block under the rim. Presuming that you are just getting this running and not spending your time but not a vast amount on it.
And keep to standard, low compression head, standard engine to take off any undue pressures?

[Stuart Giles]

Without getting into hot work you could machine up a 1/10" thick washer from a piece of silver steel to be a snug fit in the spotface around what's left of the hole. I would harden it and temper to dark straw. It looks like there's enough metal there to stop the big washer tipping if it is a good fit. You could put some Devcon or JB weld in the broken away portion at the base of the block face. It would be in compression there so should help prevent a further failure of what's left of the lug.

If I was going to do a hot repair I would use a Manganese Bronze rod to braze in a thick steel washer which would also incorporate a piece which fills the gap down to the block face. Biggish castings like these need a huge amount of heat to perform such a repair. The last one I did had a couple of hours on the top shelf of the domestic oven on maximum temperature, followed by a mate holding a propane roofing torch on the underside while I used an Oxy Acetylene torch with really big (No. 18 IIRC) nozzle on top to braze up the casting.

[Chris KC]

Your case (b) Stuart sounds very much like what has been done to the other block I have. The washer seems a good idea and will distribute load over whatever is used to fill beneath - be it metal or epoxy or something else. I'm veering toward the hot route as it sounds more like a permanent repair, I don't want this dropping off later. I'll call my welding contact in the morning and see if this sounds like something he can do. Thanks to all for input.