Mystery hole in firewall

[fattogatto]

I have a 1967 baby Elan S3 RHD undergoing rebuild. I have found a strange hole in the upper corner of the gearbox tunnel (near side - on left as facing the car from the front) just as the tunnel transitions from vertical to horizontal. It has a rubber grommet in it. In searching the pre-dismantle pictures I can find nothing protruding from that hole. Inserting a screwdriver I am met with instant resistance. I believe it is hitting the heater plenum.

Is there something I'm missing or is this possibly an addition by the PO?

Thanks,

[661]

Plenum drain hole I believe.
I think one of Paul H's videos will show this quite clearly.

[gjz30075]

Right, the plenum 'nipple' fits in it, for drainage

[fattogatto]

Thanks to all.

[alan.barker]

If you mean on the driver's side from inside there is a hole with rubber bung forward position in tunnel. This helps to access to undo screws on Fuel Pump.
Alan

[baileyman]

My plenum nipple was dry rotted. Not trusting it's design I found an interesting workaround. It's a length of bicycle inner tube with the end inserted in a 1" ring, then turned back on itself leaving the ring surrounded. Then threading the tube through the drain from the top the ring stops it nicely and it dangles past the transmission. Soon I will trim the end. The ring structure should not impede drainage as it is low.

John