Rescuing engine number.

[Chapmag]

As part of my renovation of my August 1960 Austin Seven, I had the original engine stripped down and rebuilt.
Unfortunately the guy who rebuilt the engine sheared or chiselled the engine number from the block.
I have the original engine number plate and new securing rivets( 2A895), but has anyone drilled out the old sheared rivet?
If so by what method and drill size?
TIA, G.

[woodypup59]

The rivets (also called drive screws) are very hard, probably too hard to drill.

You might be able to excavate around them enough to loosen them, but be careful not to hit the water jacket.

Spark eroding is a possibility but expensive.

[111Robin]

I resorted to gluing the plate to the block, cutting the heads off the new rivets and gluing them in place. Looks as it should and a lot less hassle.

[Peter Laidler]

Left handed diamond tipped centre drill should start, grip and eventually unscrew them. Especially if that area of the block is dammed and release/penetrating oil allowed to penetrate down the sides of the drive screws for a day or so. Heat area and then set about it with the left handed centre drill.

[mk1]

Don't try to drill them out unless you have a very fancy drill, you'll break it. Drill 2 new holes just to one side of the old sheared off hammer drive screws, then fit the plate offset slightly. One one will ever notice.

[Chapmag]

Thanks all,
I was gravitating towards the glue solution as the drilling does come with risks.
Knowing my luck (and lack of engineering skills) all the possible disasters would probably occur!!!
Thanks again, G

[111Robin]

Granted it's a bodge but purely cosmetic so I don't worry about it. I think I used Araldite.

[360gts]

I have had good luck with putting a slot in the top of the rivet and using a good screwdriver to unscrew them.
Doesn't work all the time....but worth a try.

A more lengthy solution is drilling alongside the rivet. Then, using a hard punch....drive the rivet into the newly drilled hole.
Next, drill the hole out to a larger diameter...tap and insert a threaded bolt.
Now you can drill new holes for new rivets. As I said...bit time consuming...but does work well.

[mk1]

The unscrewing method after cutting a slot in the top works great for complete Hammer drive screws, but isn't really practical f the heads have already been removed.

[Rusty old S]

The one nearest the distributor I have taken a say 3mm drill and come up underneath then small long parallel punch few taps and out it came. You must carefully eye this up. Fill the under hole with liquid metal, won’t work on other rivit

[Ronnie]

I don't know what tooling you have access to hand or drill press but you could use small tungsten/diamond burr.

[Polarsilver]

Given it is risky to drill out the remains of the drive screw .. i tried to drive the remaining sheared off pin "down" further into its Hole with hammer & punch.. was surprised how easy it moved further down that hole .. i got about another 2mm to 3mm of Hole showing within the block by this method Then cut a new Engine Plate Drive Screw length down to suit & it did fit into this shallow hole location.. this was enough to Hold the Engine Plate in place with some Loctite Bearing Fit ..this bodge worked.

Back in the Day as a Engineering Apprentice .. when i did my 6 months in the Tool Room i got quite used to using the "Spark Erosion Tool" .. where you sat at the Press Tool that you had broken off that small Thread Tap into & the task was to Eroded the hardend broken off Tap away .. this saved the day but Syd the Forman was never happy other than when i moved on to the next department inside that Factory in Cowley
Reason for this story ..Spark Erosion would get a Engine Plate Broken Drive Screw removed.