We have visited Kilchurn Castle a couple of times. One visit we couldn't find any access except bushwhacking, but we had good luck on our 2015 trip. Below is a copy of the directions I received on Trip Advisor before we went Print them out, then check them out using either Goggle Maps or a good road Atlas.
Assuming you will be at Glencoe again here are directions.I could not find the B8074 on my map ( MY NOTE - IT IS THE GLEN ORCHY ROAD) but in any case you will need to get to A82 which you would have to had used anyway to get to Glencoe.
This is the main road that runs all the way up to Inverness from Glasgow.
On the A 82 head south towards Loch Lomond / Glasgow area.
After about 25 miles you will need to take a left turn on to the A85 this is the main route to Oban.
After about 14 miles there will be a road on the left, the A 819.
As soon as you pass this turn off there is an opening among the trees/bushes it is not easy to see and is not signposted.
If you see it and miss it dont worry just a bit further up the road there is a right hand turn you can go to and turn around.
It is a very bumpy car park so go slow.
As it is just a dirt track it will not be on any map except maybe a O.S map.
Once there you will see a signpost for the castle its about a ten minute walk , there was no charge when we went.
If you dont follow any of this please feel free to ask again , as I said once you are by the A819 you are by the car park if you still miss it use the right hand turn I told you about park and just walk down to famillarize yourself.
I hope you find it ok and have a good visit this was a castle I had always wanted to go to ever since I saw a photo of it 30 years ago.
Have a good holiday and please ask if you need any more info.
over a year ago
continuing from previous message you are not that far away on the B 8074 so the directions are the same
When you get to Inverlochy turn right on to the A85 heading for Oban.
I would say the turn off is only about 4 miles down the road.
Its unlikely you will be able to see the castle from that direction its hidden by trees.
My family and I can along the A819 and were able to see the castle through a clearing in the trees (also able to get an excellent photo from this vantage point.
Hope you find it ok good luck .