[Andersljungberg]

Detta är vad skribenten säger

The 1971 and 1972 B20E / F are definitely not set up for unleaded gas and need inserts installed on the exhaust valves. I don't know whether Volvo started installing inserts for unleaded gas by 1974. That is something that you should check for. If not you should have a machine shop do that to prevent valve recession on the exhaust valves.
https://www.swedespeed.com/threads/kenn ... 42.668641/

[Amarace]

Vad är det du undrar över??