Around 4.25pm on Sunday, the elderly man was at home in Waukglen Drive, when three men forced entry and threatened him, then left with items including jewellery.
The victim was uninjured, but very badly shaken.
The three suspects are described as white and aged between 20-30 years.
One was wearing a light blue shirt with cream coloured trousers. The second man was wearing a white hooded top and dark coloured trousers. The third man was dressed in dark-coloured clothing.
They drove off in a white car.
Detective Constable Kris Elliott said: “Targeting an 86 year-old man and making him feel vulnerable in his own home is despicable.
“Our enquiries are continuing to identify and trace the three men involved and anyone with any information should call the Community Investigation Unit at Govan via 101.
"Alternatively Crimestoppers can be contacted on 0800 555 111, where anonymity can be maintained.”