Morris Minor Owners Club

Could someone let me know what drill size I should use when replacing the engine code plate, the one on the cylinder head.
The rivet size is 5/32”, many thank, John

If you intend to drill out the old rivet you may not be able to drill it out with a normal drill as the rivet is very very hard. A Cobalt drill may not eat into it either. Some have even resorted to spark erosion.
As regards drill size try a 3.5mm which is just under 5/32" which equates to 4.00mm according to my Zeus Data chart.
If possible move the rivet holes to one side of the old rivet's. Only one hole /old rivet will show.
If you do drill new rivet holes make sure that there is land (metal) between the new holes and the old rivet because if the drill and rivet come into contact the drill can snap

Thanks Phil I’m hoping to grind off the old ones to locate it as close as possible, cheers, John

If the old ones are still in place, why not try twisting them out, before grinding them off. I presume by mentioning the need to grind them, that there is still enough to grip hold of ?

Only drill as a last resort! Do as Les suggested.
Regards
Declan

Try and grind a screwdriver slot, or a couple of flats so you can twist it out.

Phil

The rivet is forced/hammered into the hole as an interference fit.

I would be very surprised if even with a screw driver slot the rivet can be screwed/twisted out.

One of the main reason for having the difficult removal of the rivet was so that the engine number could not be changed on demand.

Not all 'A' Series engines are equal even within the same CC range.

I have since found this on the Mini Mail website. They can provide new engine number plates and this pdf explains how to remove the rivets:-
https://www.minimail.co.uk/app/download ... gines.docx

philthehill wrote: ↑Wed Oct 17, 2018 7:22 pm The rivet is forced/hammered into the hole as an interference fit.

I would be very surprised if even with a screw driver slot the rivet can be screwed/twisted out.

One of the main reason for having the difficult removal of the rivet was so that the engine number could not be changed on demand.

Not all 'A' Series engines are equal even within the same CC range.

I have in the past removed these from motorcycle engine covers which are aluminium and they come out relatively easily, never tried the ones in cast iron though so I take your point.

Phil

I have never had such good luck as to get the rivet out in one piece if at all no matter how hard I have tried or process used.
Unfortunately the engine number plate needs to be removed when re-boring the engine block so the rivet head usually gets knocked off to provide a flat surface for the boring bar.

The engine no. plate on my 1275 engine was in a terrible state but luckily the previous owner had removed it.
I got the new plate from Minimail.
I also installed longer studs for the heater pipe so it can be removed to access the thermostat without disturbing the cylinder head nuts.
Regards
Declan

THAT'S a good idea!

Rob,
Part no TAM1617 Minispares
https://www.minispares.com/product/Clas ... o%20search
Regards
Declan

Although my head studs are fully home, the thread protruded enough for an additional thinned down nut, to serve the same purpose as mentioned. However handy to know longer studs are about for future rebuilds. Part number noted!

Alternative to longer studs, which were common in just that position, were extended nuts / stud arrangement to allow for the mounting frame on the oil bath air filter in about 1956 - 58.