hoping to discuss the physical differences between the 75 and 155 heads, but hoping to avoid a continuation of the 155 vs 75, which is better? my opinion, it's a matter of choice. the first 4 photos show the front cover bolt holes in the base of the head, you can not change a 75 head with a 155 as simple as changing a head and gasket on a nord, the ts motor will probably need to come out to address the differences in the bolt pattern.
the first 2 photos show the holes on the exhaust side thru which the bolt is passed from the bottom up. The 75 head is scrap and the 155 has the surface done.
the second set shows this area from the side, note that there is no metal into which you can drill and tap,
the 3rd set show the heads with a nord gasket, bolt patterm for front cover up into head is the same on the nord as the 155.
this is my first 155 head, so don't expect a-z instructions, rather this is checking the differences and adjustments and changes to be made to fit it as a replacement for the 75 head, hopefully I'll be able to upload scanned pages from the parts book that show the water pump and plumbing, and the ignition system. this head was purchased from a fellow board member, and arrived as he had acquired it, some port work done, nothing in the combustion chamber, not sure of valve angles, this head is not a priority so this will be slow.
the first 2 photos show the holes on the exhaust side thru which the bolt is passed from the bottom up. The 75 head is scrap and the 155 has the surface done.
the second set shows this area from the side, note that there is no metal into which you can drill and tap,
the 3rd set show the heads with a nord gasket, bolt patterm for front cover up into head is the same on the nord as the 155.
this is my first 155 head, so don't expect a-z instructions, rather this is checking the differences and adjustments and changes to be made to fit it as a replacement for the 75 head, hopefully I'll be able to upload scanned pages from the parts book that show the water pump and plumbing, and the ignition system. this head was purchased from a fellow board member, and arrived as he had acquired it, some port work done, nothing in the combustion chamber, not sure of valve angles, this head is not a priority so this will be slow.