Join Date: Feb 2003
Location: Saint Lazare, QC.
Since you said that the engine or sled was a 1998 670 HO which never existed am I to assume that the motor is from a 98 - 99 Summit X 670 or a 1999 MXZ 670 HO. In both cases the head design is a "Pent roof" chamber (ring shaped protrusion around the spark plug). Check the outside of the cylinder head for an "X" mark in between the spark plus just ahead of the thermostat housing. No "X" means you probably have the wrong head for the HO pistons (the squish band angle is wrong). The regular 670 has pop up domed pistons and the HO has near flat tops Mix them up and what you have happens.
Located in Western Quebec
Kilos traveled this season 2750