OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines briggs quantum 35 knocks when under load

If it only knocks under load, not with no load at the same speed, it sounds as if it may be detonation. That shouldn't happen in a Briggs unless the flywheel key is sheared and it has ended up with the ignition advanced. Does it ever kick back on the pull-start? If it isn't detonation it is probably a loose big-end bearing.